Growing
Yellow Leaves On Your Choisya? Check Your Environmental Conditions Say Gardeners
IN THIS GUIDE 1) Frost Damage 2) Transplantation Shock 3) Overwatering 4) Fungal Diseases 5) Pests Yellow leaves are often a sign that something is wrong with your choisya shrub. The challenge can be working out precisely what the problem could be. First of all, it is important to note that some choisya cultivars do actually have yellow leaves at certain times. For some types, yellow leaves in spring or leaves that turn yellow in autumn can be perfectly normal. However, if leaves are yellow at other times, are drooping, or are not on a type that typically has yellow leaves, this can be due to: Frost damage Transplantation shock Overwatering Fungal diseases Pests Read on to understand these causes in more detail. 1) Frost Damage Cold weather and drying winds in winter can cause foliage damage on choisyas, which can lead to yellow or brown leaf tips or even larger areas of dieback in more extreme cases. Choisyas can often make it through the winter unscathed in the UK, but do need to be in a sheltered position, and may need to be moved undercover if growing in containers, especially in colder regions or more severe winters. 2) Transplantation Shock Yellow leaves can be a sign, also, of transplantation shock. If a choisya plant is moved, it can be slow to recover, and roots may easily be damaged. A choisya may also experience shock if moved outdoors too suddenly from an indoors or undercover location. “If you decide to transplant a choisya, try to get as much of the root ball as possible by digging carefully around and under the plant,” explains Colin Skelly, a Master Horticulturist as declared by the RHS. “It would also help to prune back the growth at the time of transplanting as the root mass available to support this growth will suddenly be dramatically reduced. “The best time to transplant is in the autumn when the soil is still warm to allow for root growth but avoiding heat stress.” A sudden change in the environmental conditions can lead to shock and cause leaves to turn yellow. 3) Overwatering Another common cause of yellow leaves is an issue with water. Drought conditions can cause leaves to droop and turn yellow or brown and dry. However, more commonly, yellow leaves can be a sign of either excessive watering or a problem with drainage that causes waterlogged conditions. In either case, the issue is that roots are not able to transmit water to the leaves as they should – either because there is not sufficient water in the soil or growing medium, or because roots are damaged by rot in wet and waterlogged conditions. 4) Fungal Diseases Root rot can be caused by water-logging alone, but these conditions can also cause a fungal infection to set in. Other fungal diseases like verticillium wilt can also damage the roots and mean that leaves turn yellow because water and nutrients cannot reach them properly. Some other fungal infections in the leaves can also cause them to take on a mottled and yellowish appearance. 5) Pests Leaves may also turn yellow when they are attacked by sap-sucking pests, so take a look at the leaves, both the tops and undersides, to see whether you can identify any pest species on your choisyas. Fortunately, choisyas are not bothered by many pests, but scale insects and spider mites, along with slugs and snails, can occasionally become a problem.
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There Aren't A Huge Number Of Choisya Varieties, But These 9 Are Reliable Options
IN THIS GUIDE 1) C. ternata 2) C. ternata ‘Sundance’ 3) C. × dewitteana ‘Aztec Pearl’ 4) C. × dewitteana ‘White Dazzler’ 5) C. × dewitteana ‘Apple Blossom’ 6) C. × dewitteana ‘Aztec Gold’ 7) C. × dewitteana ‘Goldfingers’ 8) C. × dewitteana ‘Snow Flurries’ 9) C. ‘Royal Lace’ Choisya are popular evergreen shrubs grown in many UK gardens. If you are looking for a choisya to grow in your garden, then size is likely to be one of the main deciding factors. Some choisyas will grow much larger than others, and smaller cultivars are best for small gardens or for container cultivation. You might also wish to look for an option which reliably blooms in autumn, as well as in the spring, and might also think about the colour of the foliage, the growth habit of the particular cultivar, and some other details and characteristics. There are not a huge number of different choisyas readily available to UK gardens. Here are some of the choisya varieties you are most likely to find. Please note that all of the choisyas in this list with grow in any soil type and pH, need full sun and have to be positioned in a sheltered location in order to thrive. 1) C. ternata COMMON NAME(S): Mexican Orange Blossom HARDINESS RATING: H4 FOLIAGE: Green FLOWERS: White FLOWERING SEASON(S): Spring / Autumn / Winter SIZE: 1-2.5m in height, 1.5-2.5m spread SHOP CHOISYA TERNATA FROM £16.95 This is the plant that many will think of when thinking about Mexican orange blossom, having also been awarded the RHS AGM Award of Garden Merit. It is a medium-sized evergreen shrub that can grow to around 1.5-2.5m in height, with an ultimate spread of 1.5-2.5m. The shrub has dark and glossy green leaves which are divided into three wide leaflets. These will usually bloom in spring, then again in autumn, and the flowers can also appear in the winter. 2) C. ternata ‘Sundance’ COMMON NAME(S): Mexican Orange HARDINESS RATING: H4 FOLIAGE: Yellow FLOWERS: White FLOWERING SEASON(S): Spring / Autumn SIZE: 1.5-2.5m in height, 1.5-2.5m spread SHOP CHOISYA 'SUNDANCE' FROM £16.95 ‘Sundance’, also known as ‘Lich’ is a cultivar of the above which grows to the same size. But rather than having dark green leaves, it has bright yellow to vivid lime green leaves instead, which are brighter yellow when grown in full sun. Again, clusters of small, fragrant flowers with a white hue are borne in spring, and typically also again in the autumn. Choisya can be a great choice for a warm and sheltered spot, in full sun or sometimes in partial shade. These shrubs have great drought tolerance, so can be great for a low-water-use garden. But note that, in colder and more northern regions of the UK, some winter protection is likely to be required and these shrubs typically need well-drained soil or growing medium. So, consider your own garden and its conditions before you decide to grow choisyas where you live. 3) C. × dewitteana ‘Aztec Pearl’ COMMON NAME(S): Mexican Orange ‘Aztec Pearl’ HARDINESS RATING: H4 FOLIAGE: Green FLOWERS: Pink and white FLOWERING SEASON(S): Spring / Autumn SIZE: 1.5-2.5m in height, 1.5-2.5m spread SHOP AZTEC PEARL FROM £18.95 This option is a somewhat larger choisya, growing around 1.5-2.5m in height, with a spread of around the same. As with the above, the leaves are made up of 3-5 thin leaflets. The flowers, tinged pink in bud, open to a pure white. These flowers are around 3cm in width, fragrant and bloom in late spring and autumn. This variety has received the RHS AGM Award of Garden Merit. 4) C. × dewitteana ‘White Dazzler’ COMMON NAME(S): Mexican Orange HARDINESS RATING: H4 FOLIAGE: Green FLOWERS: White FLOWERING SEASON(S): Spring / Autumn SIZE: 0.5-1m in height, 0.5-1m spread SHOP CHOISYA 'WHITE DAZZLER' FROM £13.95 Among the smallest choisya cultivars on offer, this one grows into neat and compact mounds of thin leaflet foliage under 1m in height and width. This is another exceptionally free-flowering option, with white flowers that appear in clusters in spring, and often return for a second blooming period in the late summer and early autumn. Recipient of RHS AGM. 5) C. × dewitteana ‘Apple Blossom’ COMMON NAME(S): Mexican Orange HARDINESS RATING: H4 FOLIAGE: Green FLOWERS: Pink and white FLOWERING SEASON(S): Spring / Autumn SIZE: 1-1.2m in height, 0.5-1.2m spread “Choisya x dewitteana cultivars are hybrids between C. ternata and C. dumosa var. arizonica,” shares Horticultural Consultant Colin Skelly. “The latter species is smaller than C. ternata and has finer foliage, producing more compact options for gardeners.” This compact and upright evergreen shrub can grow to around 1.2m tall, with a spread of around the same figure. The green foliage is dissected into several slender leaflets. As the name suggests, the flowers somewhat resemble those of an apple tree, opening from pink buds to reveal white blooms. These will typically bloom in mid to late spring and again in early autumn. 6) C. × dewitteana ‘Aztec Gold’ COMMON NAME(S): Mexican Orange ‘Aztec Gold’ HARDINESS RATING: H4 FOLIAGE: Green and yellow FLOWERS: Pink and white FLOWERING SEASON(S): Spring / Summer / Autumn SIZE: 1-1.5m in height, 1-1.5m spread Growing around 1-1.5m tall and wide, this option has leaves made up of slender leaflets which open yellow and mature to green. The flowers are fragrant and white and, similar to the above, you can expect blooms in late spring and again from late summer to autumn. H4 hardy. 7) C. × dewitteana ‘Goldfingers’ COMMON NAME(S): Mexican Orange HARDINESS RATING: H4 FOLIAGE: Yellow FLOWERS: White FLOWERING SEASON(S): Spring / Summer SIZE: 1-1.5m in height, 1-1.5m spread This Choisya grows around 1-1.5m in height and spread. It has narrowly elliptic leaves which can be a vivid yellow hue in the sun, though will be greener when shaded – so for full effect, is best grown in full sun. The fragrant white flowers bloom in the late spring and into the early summer. 8) C. × dewitteana ‘Snow Flurries’ COMMON NAME(S): Mexican Orange ‘Lisflurry’ HARDINESS RATING: H4 FOLIAGE: Green FLOWERS: White FLOWERING SEASON(S): Spring / Summer SIZE: 1-1.5m in height, 1-1.5m spread A compact evergreen shrub, this choisya forms a neat mound of around 1.5m in height. The leaves are aromatic, and slender, with a deep green hue. This option is particularly free-flowering and the white flowers appear from pink buds to fill your garden with fragrance in spring and early summer. 9) C. ‘Royal Lace’ COMMON NAME(S): Mexican Orange HARDINESS RATING: H3 FOLIAGE: Gold and green FLOWERS: White FLOWERING SEASON(S): Spring FRUIT SEASON(S): Autumn SIZE: 0.5-1m in height, 0.5-1m spread This hybrid cultivar has a dense, neat and compact growing habit, with golden to lime green evergreen foliage with a lacy appearance. It grows only around 75cm tall, so resembles ‘Aztec Gold’, but is actually better for containers or tiny gardens. Mounds of white flowers bloom on the plant in profusion in the spring, It’s best grown in full sun and is H3 hardy.
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These Are The Soil Composition, Drainage & pH Levels To Aim For With Choisya Plants
IN THIS GUIDE Soil Composition, Fertility & pH Levels Aspect Drainage References With their attractive evergreen foliage and fragrant white blossoms, choisyas are a popular choice in gardens up and down the UK. Their ease of cultivation and versatility among other specimens only enhances their appeal. Originally hailing from Mexico, choisya plants have adapted extremely well to the British climate and will thrive well in most parts of the country.1 Having said that, they will perform best when their soil preferences are met and they are grown in the optimum conditions. With that in mind, here’s a quick rundown of the factors you should bear in mind when planting choisyas either in the ground or in a container. Soil Composition, Fertility & pH Levels Choisyas are largely unfussy creatures and will generally make the most of whatever soil you give them, regardless of whether it’s predominantly composed of clay, loam, sand or chalk. However, fertile soil is always preferable. It’s a similar story when it comes to the pH levels of the soil, as they will cope well in acid, neutral or alkaline soils. Having said that, choisyas don’t like any terrain which is either excessively acidic or alkaline, so temperance is the name of the game here. Perhaps more important than the quality of the soil itself is the conditions which affect it. Therefore, you may find that the following factors have more of a bearing on your Choisya’s performance than the soil composition. Aspect Generally speaking, choisyas need their fair share of sun to thrive. That’s especially true in colder parts of the country, so selecting a location with full sun (or only partial shade, at a push) is recommended. They’ll also benefit from protection from the wind and elements, so being positioned by a wall or fence is ideal. Most choisya species are hardy down to around -10°C, but will struggle with the frost in the soil thereafter. Therefore, those living in chilly regions of the UK might want to consider planting their specimen in a container to allow for ease of movement to an indoor location during winter. If planting in a pot, a general rule is that the larger the receptacle, the happier both you and your choisya will be. This is because it will not only have the space it needs for its roots to develop, but it will require watering less frequently. Drainage As with many plants, drainage is the all-important factor for choisyas, since the plant simply cannot stand getting its feet too wet, as Horticulturist Colin Skelly explains: “The soil type will make a difference to moisture holding around the roots of plants. “The main culprit for plants that like free-draining conditions is clay, with heavy clay holding onto moisture like a sponge. “In these conditions, you will need to find the highest part of the garden or amend the soil structure with de-compaction and compost to allow moisture to flow more freely around the plant’s roots.” In waterlogged soil, it will falter and fade, eventually dying due to the excess water. As a result, it’s imperative that you choose a well-draining location for your choisyas in your garden. If your soil is not naturally amenable to good drainage, you may wish to give it a helping hand by raking it over and using an aerator if you have one (a hand trowel or rake will suffice if you don’t). You can also artificially enhance drainage by adding compost or raising the planting area above the surrounding terrain via the use of a mound or berm to allow water to flow downwards more efficiently. References 1. Choisya ternata. (n.d.-b). North Carolina Extension Gardener Plant Toolbox. Retrieved March 14, 2023, from https://plants.ces.ncsu.edu/plants/choisya-ternata/
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Root Rot Or Pests? Try These Effective Hebe Treatments For Any Growing Problems
IN THIS GUIDE 1) Root Rot 2) Under Watering 3) Leaf Spot Disease 4) Downy Mildew 5) Too Much Sunlight 6) Pests References Prized for its colourful flowers and foliage, hebe is a resilient plant which adapts well to most climates and terrains and doesn’t demand too much in the way of upkeep. However, like pretty much all plants, it’s not completely impervious to growing pains. Some of the most common complications encountered by gardeners when growing hebe in their garden include: Root rot Underwatering Leaf spot disease Downy mildew Too much sunlight Pests To identify which of the above issues is afflicting your plant and, most importantly, to learn how to address it appropriately, read on for more detailed advice below. 1) Root Rot Root rot afflicts plants in soil with poor nutrients, bad drainage or excessively cold temperatures. If the ground becomes waterlogged, the roots can drown, or else fungi can develop which causes them to rot. A hebe plant suffering from root rot will be immediately apparent because all parts of the plant, including its stems and leaves, will turn brown and growth will decelerate almost entirely. Digging up the plant will reveal that the roots themselves are completely rotted, turning black and limp in the process. Unfortunately, root rot is pretty much a death sentence for your hebe specimens. The only thing to do is dig up and dispose of the affected plants, then improve the soil quality by adding nutrients and enhancing drainage. After that, it’s simply a case of planting a new hebe in the rejuvenated terrain. 2) Under Watering While root rot can occur because of an excess of water, a shortage of water can have similarly disastrous results. Under-watered plants will see their root balls dry out completely, meaning they are not able to extract the nutrients they need from the soil. The symptoms of this are most noticeable in the plant’s leaves, which will begin to become brown and discoloured. If this occurs with your hebe, check the soil around its base by gently inserting your fingers into it. It should be damp but not saturated or bone-dry. If the latter occurs, simply water the plant abundantly and apply a layer of organic mulch to retain the moisture within the soil. If it doesn’t show signs of improvement within a couple of days, it could be that the root ball is repelling the water; remedy this by adding a teaspoon of liquid soap to 10L of water and irrigating the plant over an extended period. 3) Leaf Spot Disease Officially known as Septoria, this disease is caused by a fungus growing on the plant and manifests itself in the shape of brown spots on its leaves.1 The signs are generally visible from October to February but can appear earlier in the year on occasion. Try to avoid watering from above to reduce moisture on the leaves, optimise air circulation and remove affected leaves. 4) Downy Mildew If you notice irregular brown patches on the top of your hebe’s leaves and a downy grey fungal growth on their underside, it could well be suffering from downy mildew. Hebes can be prone to downy mildew and blackspot, more so if container grown – they seem to be happy when in the ground” says Charlie Bewley from Hic Bibi Hebe Nursery. “If this occurs remove any dead leaves from around the plant don’t put the dead leaves in compost. “There are effective treatments and more biological treatments are becoming available. check the label.” This malady is caused by the growth of the fungus Peronospora grisea, which thrives in damp, cold conditions with poor circulation of air.2 If left unattended, the fungus and the mildew it causes can eventually kill your plant completely. 5) Too Much Sunlight From too little sunlight to too much sunlight, hebe plants can also suffer if they receive too much of a good thing. Overexposure to UV will become obvious if the foliage is brown, scorched, or crunchy to the touch. “I have lost a few Hebes in pots from too much exposure to strong sunlight,” shares Master Horticulturist Colin Skelly. “Think carefully when planting or placing a pot to ensure that shade is available during the middle of the day.” It’s even more easily identifiable if those symptoms only appear on one side of the plant. This concern most commonly occurs during the summer months and can be prevented by protecting your plant from the brightest of the sun’s rays. Move potted specimens indoors during peak hours (11am and 3pm) or erect a shade cloth for those growing in the ground outside. 6) Pests Hebe plants are not just pleasing to humans; they’re also an appetising prospect to all sorts of bugs and beasties, including caterpillars, vine weevils and leafcutter bees. You can identify which insect is attacking your plant by the signs they leave behind. For example, caterpillars will deposit tiny excreta on the lower leaves of the plant. Vine weevils take small, notched chunks out of the foliage, while leafcutter bees will remove much larger and rounder holes from them. Caterpillars are best dealt with by removing them manually, while vine weevils can be treated using diatomaceous earth or sticky traps. As for leafcutter bees, they provide important pollination service for the rest of your garden and the wider environment, so I find it’s best to just let them have a slice of leaf every now and again! References 1. Lee, J., Orosa, B., Millyard, L., Edwards, M., Kanyuka, K., Gatehouse, A., Rudd, J., Hammond-Kosack, K., Pain, N., & Sadanandom, A. (2015, March 24). Septoria leaf blotch disease in wheat. New Phytologist Foundation. Retrieved March 16, 2023, from https://www.newphytologist.org/news/view/81 2. Peronospora grisea. (n.d.). Peronospora Grisea (Hebe Downy Mildew). Retrieved March 16, 2023, from https://www.bioimages.org.uk/html/Peronospora_grisea.htm
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Regular Rejuvenation Pruning Helps Prevent Lilac Becoming Unsightly And Unwieldy
IN THIS GUIDE When To Prune Lilac 1) Prepare Your Tools 2) Deadhead Throughout The Blooming Season 3) Prune After Flowering 4) Tip-Off Longer Stems 5) Thin Out 6) Strip Away Suckers What To Do With Overgrown Lilacs With their lusty blooms and intense flora fragrance, lilacs are a popular shrub or small tree throughout the UK. As deciduous perennials, Syringas are hardy creatures which will lose their leaves each autumn but come back with renewed vigour the following spring. Having said that, it’s important to prune your lilac bush or tree regularly to avoid it becoming unruly and unkempt. “Regular rejuvenation pruning will keep a lilac in more vigorous plant size with larger flowers at a lower height, where they can be better experienced and enjoyed free of any pests,” says David Gressley, from the International Lilac Society. Left to its own devices, a lilac tree can exceed 8-9m in height, while its splayed branches and sparse blossoms make it unsightly and unwieldy. Fortunately, you can avoid this outcome by keeping on top of its pruning. While this might be a time-consuming process when you get down to it, you only have to undertake it once a year. Follow the steps outlined in the guide below and you can’t go wrong. Difficulty Easy Equipment Required Gardening gloves, pruning shears, pruning saw, cloth, isopropyl alcohol, fertiliser When To Prune April-June (after flowering) When To Prune Lilac Pruning your Syringa bush or tree at the right time is all-important to its continued growth and development, especially in the immediate future. That’s because the following year’s buds begin development almost straight after the last ones have died. As a result, leaving pruning too late in the year could jeopardise the blossoms of the following spring. For that reason, it’s advisable to tackle the job as soon as the flowers have begun to fade on your bush. This will give the new buds plenty of time to mature, keeping the plant healthy over winter and ensuring a stronger yield of blooms next year. With that in mind, pruning can take place anywhere from April to June, depending on the climate where you live and the way in which your particular lilac species reacts to it. July is generally too late to undertake maintenance without incurring adverse effects on the following year’s blooms, while autumn pruning is out of the question altogether. 1) Prepare Your Tools I can’t stress enough how important it is to keep your tools in top condition. Blunt shears can result in unclean cuts that foster bacteria and encourage disease, while those which haven’t been properly cleaned can spread both of the aforementioned blights throughout your garden. “Keeping secateurs and loppers sharp is a must as using blunt tools can cause more harm than good,” says Colin Skelly, a Master Horticulturist. “I clean my pruning tools after every use, cleaning away any sap and dirt and using a sharpening stone to ensure that when next used they are sharp. “Every month or so I’ll use a diamond file to rework the edge after a few uses.” Therefore, you should keep your pruning shears as sharp as you can – don’t be afraid to replace them altogether if they’re beyond saving. You should also use a clean cloth soaked in isopropyl alcohol to thoroughly clean the blades before and after use, drying them after the act. Gardening gloves are a must for this part of the process, too. 2) Deadhead Throughout The Blooming Season Lilacs make a lovely cut bouquet for indoor arrangement, but many people feel they are cutting down the plant in its prime by deadheading in this manner. Actually, nothing could be further from the truth; by deadheading blooms that are at or just beyond their peak, you’re actually helping your Syringa. That’s because it allows the plant to devote all of its energies to new growth, rather than sustaining flowers that are already on the way out. Make the cut at the base of the flowerhead and repeat as often as desired or as possible. 3) Prune After Flowering Once the flowering season has run its course, you shouldn’t waste any time in tackling your pruning tasks. To do so, cut back the stem to the first set of leaves beneath the flowerhead. Make the cut using sharpened, clean pruning shears while wearing gardening gloves. Pruning to this point is a good strategy because it will guarantee that you do not accidentally remove next year’s buds, but still enhance flowering as much as possible come the following spring. Pruning each year in this manner will also prevent the plant from becoming unruly. 4) Tip-Off Longer Stems As well as pruning back flower heads, you should also keep an eye out for longer stems which may not carry any blossoms, but are stretching out beyond the main body of the plant. These will also require your attention so as to keep the shrub’s aesthetic shape intact. Again, you’ll want to pare the stem all the way to where the nearest side shoots are emerging. If it doesn’t yet have any side shoots, look for buds or nodes that are likely to develop into shoots in the future and make the incision just above these. 5) Thin Out Next, you’ll want to thin out the plant to ensure it enjoys a good circulation of air amongst its branches and foliage. This helps to prevent the development of things like mould and fungus, which are detrimental to the growth of your lilac bush or tree. When thinning out your plant, always target the dead, dying or discoloured stems and branches first. This will stop these liabilities from sapping the lilac of its energy. You can also chop back stems that are more than 5cm in diameter, which will keep the plant from becoming too tall. A pruning saw may be necessary for extra thick and tough stems. 6) Strip Away Suckers Suckers are baby trunks which sprout from or near the base of the plant and provide competition for nutrients and energy for the main trunk. As such, they should be removed for both aesthetic and practical reasons, especially if your lilac specimen is grafted. I find the best results can be achieved by gently removing the suckers from the soil with your (gloved) hands since this can pull up the roots entirely. Then you can plant the sucker in a pot of its own and enjoy a new lilac plant altogether. What To Do With Overgrown Lilacs If you’ve not had time to properly address the upkeep of your lilac bush or tree in recent years – or you’ve inherited an overgrown one from someone else – you might find that the plant is in need of a more intensive pruning job. This type of work is best undertaken late in winter, once the final frost has passed. That’s because extremely cold temperatures can damage the wounds created when pruning the tree. However, by this point, the plant has not yet started to flower and is still dormant. Begin by targeting the diseased or dying branches first, then move on to the oldest parts of the bush or tree. Try to keep a mixture of old and new growth so as to allow the lilac to continue thriving and never remove more than a third of its foliage in a year. For trees that have become too tall to be manageable, you can cut back their height to bring them under control. Again, don’t chop back more than a third; you can always repeat the process in future years if need be. Be mindful that this type of aggressive pruning can endanger the next spring’s blossoms, but it will be worth it in the long run. Once the aggressive pruning job is complete, give the plant the best chance of rejuvenation by applying fertiliser liberally to its base. This restores the appropriate balance in pH levels to the soil and grants the plant access to the nutrients it needs to recover.
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Hibiscus Plant Care Findings From Our Interview With The International Hibiscus Society
IN THIS GUIDE Overview Recommended Varieties Growing Hibiscus Planting Ongoing Hibiscus Care Common Problems Propagation References Hibiscus is a large genus of flowering plants: there are hardy hibiscus types that can thrive outside in many UK gardens, and tropical types can be grown as houseplants indoors. In this article, we will focus on two of the most common Hibiscus in cultivation – the hardy Hibiscus syriacus, also known as Rose of Sharon, Rose Mallow or Tree Hollyhock, and the popular houseplant Hibiscus rosa-sinensis. We interviewed Darren Eminian to help produce this guide – Darren is the President of the Southern California Hibiscus Society and the International Hibiscus Society. “My passion for hibiscus comes from the incredible and second-to-none combination of multiple colours on large blooms that few, if any, other species of plants can produce” says Darren. Explore his tips for making the most of your plants in the guide below. Overview Botanical Name Hibiscus Common Name(s) Rose of Sharon, Rose Mallow, Tree Hollyhock Plant Type Shrub / Tree Native Area Temperate subtropical and tropical regions Hardiness Rating Varies Foliage Deciduous Flowers Trumpet-shaped with numerous hues When To Plant April-May (for hardy varieties grown outdoors) When To Prune June There are several hundred different species of hibiscus, which are included within this diverse genus of flowering plants in the Malvaceae, or mallow, plant family.1 Hibiscus can be found around the globe, in temperate, subtropical and tropical climes.2 The genus includes trees, shrubs and herbaceous plants – both perennial and annual. Of all the plants within this genus, two are most widely cultivated as ornamental plants: H. syriacus (grown outdoors in the UK) and H. rosa-sinensis, which is grown as a houseplant in temperate areas. The former is by far the easier option. When planted in an appropriate spot and cared for correctly, H. syriacus can flower extremely well from late summer into early autumn. H. rosa-sinensis, also known as tropical hibiscus, is usually grown indoors, though it may succeed in a warm greenhouse as long as this remains frost-free over the coldest months. They can be rather difficult to grow successfully and are not necessarily to be recommended for novice houseplant gardeners, but when successfully grown, can bloom beautifully from May right through to October. Recommended Varieties Some varieties of H. syriacus to grow in the UK include: ‘Ardens’ ‘Chiffon’ Series ‘Duc de Braband’ ‘Marina’ ‘Monstrosus’ ‘Oiseau Bleu’ ‘Red Heart’ ‘Sugar Tip’ ‘Totus Albus’ ‘Woodbridge’ Some H. rosa-sinensis cultivars include: ‘Columbine’ ‘Holly’s Pride’ ‘Karmen Keene’ ‘Me Oh My Oh’ ‘Peaches & Cream’ ‘Pink Frost’ ‘Sprinkle Rain’ ‘Tarantella’ ‘Velvetine’ ‘White Swan’ “With H. rosa-sinensis, I prefer to grow most varieties from the ‘Hidden Valley’ hybrid collection, because they are the only hybridizers dedicated to creating new hybrids that have strong and vigorous bushes with large blooms that bloom often,” Darren explains. Growing Hibiscus Your first decision, of course, will be whether you wish to grow hibiscus in your garden or indoors. In order to make this decision, you will have to determine whether you can create the right conditions for either hardy or tropical hibiscus where you live. The plant care requirements outlined below will help you understand what is possible and the conditions each of these two common hibiscus types require. Planting “Every growing location has it’s own unique parameters so it takes time to see what tweaks need to be made,” says Darren. “The base need for hibiscus is a soil mix that is light and full of air all the time even when wet. Hibiscus will struggle to survive in clayey soils in the long term.” Dig a hole large enough to accommodate your new plant in a suitable location and place the new shrub in the hole you have excavated, or place your hibiscus in a container filled with a suitable growing medium. Mulch with an organic matter around your new plant to retain moisture over the summer months and to provide slow-release fertility. When To Plant When growing hardy hibiscus outdoors, you will usually purchase and plant your new shrub in late spring. Tropical hibiscus can be purchased and potted up at any time, though again, repotting in spring is generally best. Where To Plant H. syriacus should be placed in a sunny spot which is as warm and sheltered as possible. This plant will be easier to grow in the south, or in very sheltered city gardens where your plants are less likely to be impacted by frosts. You can also plant in a container so you can bring your plant undercover in the coldest part of the year. In a suitable spot, sheltered from cold winds, this plant should make it through the UK winter unscathed, though some protection may be necessary for more northern areas. H. rosa-sinensis is grown indoors, in a location with bright but not direct sunlight. Growing these plants in a frost-free conservatory or a bright bathroom can be ideal. Container Growing Both types of hibiscus under discussion in this article work well in containers. Choose a container which can drain relatively freely, and fill with a medium which meets the soil requirements and other environmental needs discussed below. Ongoing Hibiscus Care H. syriacus placed in a suitable location should usually be a relatively easy and trouble-free plant, which should require little care and attention, especially once well-established. H. rosa-sinensis can be more challenging to grow, but following the care guide below should help you to grow this plant as a houseplant in your home. Darren argues: “The Golden Rule of growing hibiscus is ‘What you see today was caused by events 2-3 weeks ago’. “So you have to keep track of inputs like weather, temperature, water or rain, what you fed them and so on…so you can get to the cause of a problem. “Being very patient and a keen observer is key so you can track inputs and start to figure out what works and what doesn’t. “Understand that you might lose quite a few plants as you come down the learning curve which can take 2-3 years minimum.” Soil Requirements H. syriacus requires a moist yet free-draining soil or growing medium which is ideally neutral or slightly alkaline. If growing in a container, a loam-based, peat-free compost is ideal. H. rosa-sinensis also requires a moist yet free-draining medium, and it is essential to choose containers which allow water to drain away relatively freely for both types. Watering H. syriacus should be watered regularly during dry spells during the growing season when rainfall is in short supply. However, these plants are relatively tolerant of dry conditions once established. The “number one problem is too much water or not enough air in the soil” according to Darren. “Hibiscus roots are tender and vulnerable to root rot.” As such they do not do well with sprinklered water: “they do better with a drip system and if you can install a fertiliser injector that is a great way to get them to thrive.” Remember that plants grown in containers will usually need to be watered more frequently. Water indoor-grown H. rosa-sinensis regularly from spring through to autumn, but always let the top few centimetres of the potting mix dry out before watering once more. Remember to cut down on watering during the dormant period, watering only when the top few centimetres of the growing medium are dry. Temperature & Humidity H. syriacus can cope with the UK winter but will need a warm and sheltered spot to flower well, which is why they are easier to grow in the south. A spot in a sunny courtyard garden or against a south-facing wall might be ideal to maintain the summer and early autumn temperatures required for a good flowering display. H. rosa-sinensis cannot cope with temperatures below 7-10°C. They must be kept in a location where it does not drop below these minimum temperatures. Tropical hibiscus also requires high humidity. They can drop their buds if the humidity drops too low so it is important to mist regularly or to move to a bathroom or another more humid location. Feeding “For feeding, hibiscus needs lots of potassium, which is key for root development and health,” Darren shares. “As their roots are tender, this goes a long way in helping them become established and strong. They don’t need much in the way of nitrogen, phosphorus, or other common plant nutrients.” With this in mind, H. syriacus should be fed with a high-potassium organic liquid feed each year in the spring. It can also be beneficial to add a thick organic mulch around the plants in autumn, for slow-release fertility as well as for a range of other reasons. Indoor-grown hibiscus should be fed once every couple of weeks from spring to the beginning of autumn with a high-potassium organic liquid plant feed. Overwintering As Darren explains, “H. rosa-sinensis is a tropical plant, so it isn’t genetically bred for seasons and cold weather events.” This does not, however, mean that you can’t or shouldn’t grow your hibiscus outside here in the UK. A hard frost in autumn may well cause your H. syriacus to die back, but this is not something to worry about. This is a deciduous plant and the plant should regrow from the base the following spring. You might think that your plant is not regrowing, but you should note that the plants develop slowly in spring and new growth can be slow to appear. Wait until June before you worry about the lack of new growth. “Established woody H. syriacus plants are normally fully hardy in most parts of the UK and resume growth in mid to late spring,” shares Master Horticulturist Roy Nicol. In colder and more northern areas, it is best to add a thick mulch of carbon-rich organic matter around the base of the plants in autumn to make sure that they overwinter successfully. In particularly cold areas, you might wish to take container-grown plants into a greenhouse or conservatory – though this is not usually required. Make sure that you have cut back on watering H. rosa-sinensis indoors during the winter months during its period of dormancy. Pruning & Training After around three years, once a H. syriacus is established, or after it reaches a height of around 1.5m, it is a good idea to start pruning the plant annually to keep it in shape. While not always strictly necessary, pruning can help prevent the outer branches from falling outwards with the weight of their leaves. H. rosa-sinensis should be pruned each year in early spring. Prune back long shoots to 5-7cm from their base, shorten the previous year’s growth to create a main framework of branches, and remove thin or straggly non-flowering stems. “As both types of Hibiscus flower on the new growth produced in the current year, timing is important to ensure good flowering, so pruning should be carried out just before growth starts in early spring,” advises Roy. “Delayed and reduced flowering will be produced if pruned later than this.” Common Problems “As you problem-solve issues with your hibiscus it might take most of one growing season to see if what action you took worked or not” says Darren. “So the learning curve for becoming an effective hibiscus grower can take 2-3 years minimum as you figure out the correct inputs needed and actions to take when problems arise.” Issues with H. rosa-sinensis are usually environmental, but look out for spider mites, which can become a problem – especially where humidity is too low.3 Root Rot Many times when Hibiscus are struggling with root rot their leaves will become pale and veiny – which to many gardeners is an indication that the plant is lacking nutrients like iron, magnesium or nitrogen. “So they water in supplements which is the exact opposite of what the roots need which is more air in the soil. “The additional water can prove to be fatal. “Instead back off on watering for a couple weeks and check the soil with a water meter to see how wet it is deep down where the roots are” says Darren. “Changing the soil mix many times is the difference maker but what you use depends on the climate and resources available to you so it differs with each region.” Pests Pests are another big challenge in the more tropical, humid areas of the world, but not particularly in UK growing conditions. Sometimes even with ideal climate conditions, pests can prove to be a never-ending problem greatly reducing the performance of a hibiscus. Darren says: “unfortunately we have tested many of the organic remedies and have found very little success with them, so proper and careful treatment with specific insecticides/miticides is key”. Of course we would always argue that this should be a last resort where organic solutions are not fruitful. Propagation H. syriacus can be propagated by means of seed, softwood cuttings or layering. Taking softwood cuttings in spring is usually the easiest option. While it can be somewhat more challenging to root them successfully, H. rosa-sinensis can also be propagated most easily by means of softwood cuttings. However, this is very hard with many hybrid cultivars and may not be very easy for most home growers. If you have any specific questions, Darren recommends that you reach out to hibiscus specialists, like those in the International Hibiscus Society, for relevant tips and tricks. References 1. The Editors of Encyclopaedia Britannica. (1998d, July 20). Hibiscus | Description, Species, & Uses. Encyclopedia Britannica. Retrieved March 17, 2023, from https://www.britannica.com/plant/hibiscus 2. Hibiscus History. (n.d.). Hidden Valley Hibiscus. Retrieved March 17, 2023, from https://www.hiddenvalleyhibiscus.com/history/earlyhistory.htm 3. Hibiscus. (n.d.). University of Florida, Institute of Food and Agricultural Sciences. Retrieved March 17, 2023, from https://gardeningsolutions.ifas.ufl.edu/plants/ornamentals/hibiscus.html
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Azaleas Make Excellent Container Plants - Just Be Sure To Get These Factors Right
IN THIS GUIDE Are Azaleas Suitable For Pots? Choosing A Container Container Compost Potting Up Azalea How Many Can You Plant Per Pot? Potted Azalea Care Azalea is a subsection within the Rhododendron genus which provides plenty of really attractive evergreen or deciduous shrubs for your garden. Though Azaleas were once categorised as a different species, they are now placed alongside other Rhododendrons within the same genus. They can be an excellent choice if you are looking for a flowering shrub for your garden. However, growing Azaleas requires acidic soil, so if you have alkaline soil, you might wonder whether you can grow azaleas in pots. You might also wonder if you can grow Azaleas in pots if you don’t have a big garden. Are Azaleas Suitable For Pots? The good news is that many different types of Azalea make excellent container plants. Some hardier types with more compact growth habits make ideal plants for an outdoor container garden and some tender types can even be grown indoors as houseplants. When deciding which Azalea to grow in a container, it is important to consider the growth habit of the particular cultivar you are considering, and the size to which it will eventually be expected to grow. Smaller options are generally best for container cultivation. Choosing A Container When choosing a container for Azaleas, make sure that the pot is large enough to accommodate the rootball with just a little space around each side. Remember, a container that is too small will limit growth. However, Azaleas like reasonably free-draining conditions, so it is important to choose a container that is not too large, as this could contribute to water-logging. You should also make sure that the container you choose has adequate drainage holes at the base. Container Compost Azaleas typically require an acidic growing medium and they thrive in a pH between 5 and 6. Create or purchase a peat-free, ericaceous compost if you would like to provide the optimal conditions for a potted Azalea. Potting Up Azalea When potting up an Azalea, make sure that the rootball sits close to the surface of the soil as these are shallow-rooted plants. Ensure that the plant is at the same depth in its new container that it was in its previous pot. Place some of your ericaceous growing medium in the base of the new container. Gently place the plant into the pot, making sure that the root ball has a little space all around. Fill in more of your growing medium around the sides, firming it in place gently, making sure that there are no air pockets. Water it in well, allowing excess water to drain away. Finally, it is best to mulch the top of the pot or other container with an ericaceous mulch, to maintain high humus and fertility, and replenish nutrients in the container over time. A mulch will also help maintain pH levels and reduce moisture loss, helping to keep the medium moist. How Many Can You Plant Per Pot? Typically, you will plant a single Azalea in one pot since most of these shrubs will take up the space on their own. However, you might also consider choosing a larger container and planting a small and compact Azalea alongside other acid-loving plants, such as heathers. Potted Azalea Care How precisely you need to care for Azaleas in containers throughout the year will depend on which cultivars you are growing, how hardy or tender they are – and where exactly they are grown. Where To Grow Outdoor potted Azaleas should be positioned in a sheltered location, in full sun or partial or dappled shade. Indoors, tender Azaleas should be placed in a room with good ventilation, with dappled or indirect light. Ideally, they should be kept in a room where temperatures remain between around 16-18°C. Watering The growing medium in the pots for Azaleas, indoors or out, should be kept moist but not allowed to become drenched or waterlogged. Try to use rainwater to water your Azaleas where possible. You may be able to use tap water, but if your tap water is alkaline, this will not be ideal for these acid-loving shrubs. “A rule of thumb that I use is, if the kettle where you are growing has limescale then you have hard water (alkaline), so avoid watering your ericaceous plants with tap water,” says Horticultural Consultant Colin Skelly. Feeding Azaleas growing in containers outside will benefit from the addition or replenishment of an acidic mulch of conifer bark chippings or leaf mould each spring. It can also be a good idea to feed weekly through spring and summer with a weekly organic, ericaceous fertiliser. Houseplant Azaleas will also benefit from an ericaceous mulch on the top of the container each spring, or from completely repotting in the spring with a new, fertile growing medium if the growth seems poor or you are dealing with an Azalea forced to flower in winter. A weak liquid feed of black tea can be good for Azaleas, and can help increase the acidity of the compost. It should also help to encourage repeat flowering the following year. Feed weekly while the plant is in active growth. Deadheading & Pruning Azaleas will not usually require much pruning at all, but it is a good idea to consider deadheading, as this can often encourage these shrubs to bloom for longer, and can also help to keep the plant looking good. Deciduous Azaleas can also respond well to a hard cutting back on occasion. Winter Make sure that you know the hardiness rating of the Azalea you are growing. Some outdoor Azaleas will be fine outside year round at least in some areas, but others will need to be moved to a more sheltered, warmer spot over the coldest part of the year. This makes it ideal for growing these varieties in containers. When growing Azaleas indoors, to encourage them to flower once more the following year, it is best to move them to a cooler location in Autumn. Many Azaleas are not too difficult to grow in pots and can make great container plants, but make sure that you provide the right growing conditions for these shrubs to thrive.
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How To Provide Fertile Conditions For Azaleas Grown In Any Manner
IN THIS GUIDE Feeding Azalea In The Ground Feeding Potted Azalea Azaleas, whether growing in the ground or in containers, do need fertile growing conditions. These are plants which will do best and flower most abundantly when provided with all the nutrients they need. Fortunately, feeding Azaleas, whichever type you are growing and wherever you are growing them, is relatively straightforward. How and when precisely you will feed Azaleas depends on whether you are growing your Azaleas in the ground or in containers. We have outlined everything you need to know about feeding Azaleas below. Feeding Azalea In The Ground When growing Azaleas in the ground, the most important factor in growing these shrubs successfully is creating a suitable growing environment. The soil should be fertile, and high in organic matter. It should be moist yet free draining, and should ideally have a pH of between 5 and 6. When these growing conditions are provided, Azaleas growing in the ground should not require much additional feeding. The key is to make sure that you maintain healthy soil around these shrubs by mulching around each plant with an organic mulch. For Azaleas, you should choose a mulch made up of acidic materials, like leaf mould, pine needles, or conifer wood chips. “Many arborists collect wood chips as a by-product of their work and often they are only too happy to let you have some if you ask,” shares Colin Skelly, Master Horticulturist. “If you see a conifer being chipped, that’s a good opportunity to re-use it locally. “Large pine trees shed large amounts of needles, so if you have a friend or neighbour with one or more in their garden, grab some if they’ll oblige.” This mulch should help to replenish nutrients within the soil and maintain the acidic soil conditions required for most Azaleas to thrive. This mulch should be placed upon planting, and should be replenished each year in the spring. Aside from mulching and maintaining healthy soil around your Azaleas, further feeding will not usually be required. However, you might also consider adding an organic fertiliser, such as blood fish and bone, upon planting or if the growth seems poor in the spring. Feeding Potted Azalea Azaleas growing in pots should be grown in a good quality peat-free ericaceous compost. To maintain fertility, the top 5cm of this growing medium should ideally be changed each year in spring, and I find it’s also best to replace the growing medium entirely every 2-3 years. It can also be a good idea to leave a little space at the top of containers so that you can add a layer of ericaceous mulch, as you do when planting in the ground. Mulching around the top of containers will help to replenish nutrients, keep the mix acidic, and conserve moisture in a pot. In addition, however, Azaleas growing in containers will also do best if provided with a weekly liquid organic feed through the spring and summer months. For example, it can be a good idea to feed Azaleas with black tea, to maintain acidity and keep them growing strong.
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To Help Azaleas Through Winter, Work Out Your Garden Micro-Climate And Plant Hardiness
IN THIS GUIDE Winter Care For Outdoor Azaleas Winter Care For Indoor Azaleas Azaleas are attractive shrubs, which come in tender or more hardy varieties. Some are suited to growing indoors year-round, whilst others can work outside year-round in your garden. In order to understand how to care for Azaleas in winter, you need to be clear about the hardiness of the particular variety that you are growing. Some outdoors grown Azaleas will be fine outdoors in winter in at least some areas, but others will need to be moved to a more sheltered, warmer spot over the coldest part of the year depending on their hardiness rating. Move tender Azaleas growing indoors, including those forced to flower for Christmas, to a cooler location with temperatures between 6-10°C. You can then move them back when the temperature is warmer in spring. For more details, make sure to read on. Winter Care For Outdoor Azaleas In order to understand whether or not you can keep an Azalea outside in your garden all year round, you need to understand hardiness ratings, as well as the conditions where you live. Many Azaleas typically grown outside in the ground in UK gardens are H4-H6 hardy. If an Azalea has a rating of H4, that means it can cope with outdoors conditions in an average winter in most of the UK, except for inland valleys, high altitude locations, and the far north. In harsh winters, they may experience some damage in colder gardens. Note that if growing in pots or containers, these plants are more vulnerable to harsh winter conditions. If growing one of these slightly less hardy options, make sure that it is growing in a reasonably sheltered location, out of drying, cold winds and not in a frost pocket. “I like to work out the micro-climate of a garden,” says Colin Skelly, Mater Horticulturist and Garden Consultant. “There can be a few degrees difference between the coldest and warmest parts of the garden in both winter and summer. “For potted Azaleas in winter, work out the most sheltered part of the garden.” “Typically this might be under the canopy of trees and shrubs or in the lee of a garden building or house – providing shelter from both wind and frost.” If necessary, move plants in a container to a more sheltered and protected spot, or undercover. Even the hardiest types are more vulnerable if growing in containers. Winter Care For Indoor Azaleas Indoors Azaleas such as Rhododendron simsii are not suitable for outdoor cultivation. They are often bought as pot plants and are forced to flower early, which is usually in winter. They can be grown indoors in a cool, bright location, or in a greenhouse or conservatory. If you wish to keep such a plant to flower again the following year, place them in a cooler location in autumn or after flowering. Then move them back to a bright location, around 16-18°C, in the spring. With some luck they should then flower again the following year, but if forced before purchase, will typically flower later than they did the previous year.
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