|Official Plant Name||Gladiolus|
|Common Name(s)||Sword Lilies|
|Plant Type||Bulbs / Perennials|
|Native Area||Asia, Mediterranean, Europe, South Africa & Tropical Africa|
|Hardiness Rating||Differs by variety|
|When To Sow||March, April|
|Flowering Months||June, July|
0.5 – 1M
0 – 0.1M
June – July
Chalk, loam, sand
Gladiolus bulbs are technically ‘corms’.
Gladioli are beautiful flowers, which can look great in your garden, whether you grow them in the ground or in pots.
In this article, we will look at these plants in a little more depth. You will discover why it could be a good idea to grow some, which varieties to consider, and where you might want to grow them in your garden.
You will learn when to plant the bulbs, how to plant them, and with what. And you will learn how easy it is to care for the plants you grow.
What are Gladioli?
Gladioli are perennial flowering plants which grow from round corms which resemble those of the crocus.
Plants in this genus, in the Iris family, are sometimes called ‘Sword Lilies’ and the name comes from the diminutive form of the Latin for ‘sword’.
There are around 300 different species of Gladioli native to Asia, Mediterranean Europe, South Africa and tropical regions of Africa.
Many species have been used in hybridisation, and now there are many, many varieties out there for gardeners to choose from.
The main hybrids used in horticulture today have been obtained through interbreeding of four or five different species. The main hybrid groups are called ‘Grandiflorus’, ‘Primulines’ and ‘Nanus’.
Gladiolus have sword-like leaves, and tall flower spikes with funnel-shaped blooms in a huge range of colours.
They fell out of fashion for a time but are now making a resurgence.
Why Grow Gladiolus?
Gladioli are sometimes thought of as quite fussy and stolid as a garden choice.
With a heavily floral scheme, they can sometimes create a rather old-fashioned appearance to a garden bed, border or pot. However, alongside grasses and lighter perennial blooms, they can look great and bring good contrast to a design.
As well as looking good in beds, borders and containers, Gladioli also make very good cut flowers, to bring into your home.
The flowers can bloom between March and August, depending on when they were planted, and which variety or varieties you are growing,
You might be interested to hear that gladiolus flowers are also edible. You can use the mild-lettuce like petals as you would use squash blossoms.
With some varieties, the corms also have culinary uses and are considered a delicacy.
Varieties of Gladiolus to Consider
There are a huge range of Gladioli to consider growing in a UK garden. Some options to consider are:
- Gladiolus ‘Robinetta’ (recurvus hybrid) (AGM)
- Gladiolus communis subsp. Byzantius (AGM)
- Gladiolus murielae (Abyssinian gladiolus) (AGM)
- G. italicus (Field gladiolus)
- G. papilio (butterfly sword gladiolus)
- G. cardinalis (waterfall gladiolus)
- G. tristis (evening flower)
- G. ‘Trader Horn’
- G. ‘Charming Beauty’
- G. ‘Belle de Nuit’
- G. ‘Vera Lynn’
- G. ‘The Bride’
- G. ‘Happy Weekend’
- G. nanus ‘Charm’
- G. ‘Miss Green’
Of course, these are just some of the many beautiful options that you could consider growing in your garden.
Where To Plant Gladiolus Bulbs
It is important to remember that Gladioli come from hot and sunny places. So it is important to choose a location in your garden where they will be able to enjoy a sheltered spot, with as much sunshine as possible.
Gladiolus varieties can be grown in the ground in a sunny bed or border, or in a container, as long as moist yet free-draining conditions can be provided.
You can plant directly into the ground as long as there are fertile conditions and as long as the soil does not become waterlogged. If growing in the ground, be sure to add plenty of organic matter such as compost or well-rotted manure.
In more northern parts of the UK, Gladioli are unlikely to overwinter successfully in the ground, So it can be better to grow these in containers that can be moved undercover.
However, you can also grow them in a border in summer and mulch heavily for protection, or you can lift the corms for winter storage.
When To Plant Gladiolus Bulbs
Gladiolus bulbs should be planted in spring, in March or April.
If you want successional colour and blooms, it is best to plant a handful each week from March onwards for a more extended display.
The corms can be planted in pots even if they will eventually be grown in a border, so you can transplant them into the garden once the weather warms.
Gladiolus bulbs can be planted directly into the border after all risk of frost has passed.
For best results, it is better to plant in pots earlier and successionally for an extended season of blooms.
How To Plant Gladiolus Bulbs
To plant gladiolus bulbs, you will first need to prepare a suitable site, or choose and fill a container.
Terracotta pots which have good drainage and dry out more quickly are far better than plastic pots for growing gladioli (and are a more eco-friendly choice too).
Be sure to ensure that you cover the drainage hole with a crock to make sure that water drains freely.
For most gladioli you will need a container that is at least 40cm in diameter. However, compact varieties can be grown in smaller pots.
Fill your pot with a free-draining growing medium, a good quality peat-free compost mix with plenty of sand or grit mixed in to improve the drainage is ideal. (If planting in a garden with heavy clay soil, amend the soil with plenty of organic matter and consider adding grit or sand to the base of the planting hole.)
Plant the bulbs to a depth of around 15cm and around 10-15cm apart. Make sure you plant the bulbs the right way up, with the pointy end upwards.
Gently cover over the bulbs with your compost or soil, and water them in. Then top the containers with a mulch to retain moisture, especially if growing in pots since these will dry out more quickly.
Though gladioli like free-draining conditions, the medium should also remain moist through the growing season.
Companion Planting With Gladiolus
Gladiolus do not bring any particular benefits for other plants growing close by.
But choosing the right companions for Gladioli can help you achieve an attractive display. In larger containers, for example, or in a bed or border, you might pair a number of different Gladiolus varieties.
Caring For Gladiolus
Gladiolus are not particularly difficult to care for if you grow them in the right spot. But there are a number of things that you have to get right to grow them successfully.
One thing to think about is that most Gladiolus varieties will need some form of support.
Usually, the plants will have to be staked before the flower spike emerges. Remember, you do not necessarily have to buy in your plant supports.
You may be able to make use of branches or bamboo canes grown elsewhere in your garden.
You should tie in your plants to your stakes to make sure that they do not flop over or become damaged as they grow.
Make sure that you water well during the growing season, especially when growing gladioli in containers.
Just make sure that the water can drain freely, and the soil or growing medium is kept consistently moist, but not damp and waterlogged.
For best results, feed your gladioli with an organic liquid feed while it is in flower.
An organic feed suited to tomatoes will work well for gladioli too. For example, you might use a liquid feed made from comfrey for the purpose.
This potassium rich feed should encourage healthy and beautiful flowers.
Pests and Problems
Gladioli can be bothered by slugs, and also by sap-suckers like thrips and aphids.
Taking care of wildlife in your organic garden, and boosting biodiversity can help keep pest populations under control.
Make sure you attract slug-eating creatures, and predatory insects like ladybirds and lacewings to your garden to reduce the chances of these problems occurring.
You should also remain vigilant, and remove affected foliage and blooms quickly when you spot an insect infestation.
As mentioned above, if you live in more northern parts of the UK, gladioli are unlikely to be able to survive in the ground over winter without some form of protection.
In some areas, and with some hardier varieties, you may be able to overwinter the corms successfully by mulching heavily with a carbon rich mulch of straw or dried leaves.
However, in some areas, you will have better results if you lift the corms out of the ground and overwinter them in frost-free conditions.
To store lifted corms over winter, unearth the corms and divide them up.
Cut each stem back to within a couple of centimetres of the corm. Break off the old corm and gently clean new ones of soil and dead layers.
Discard any corms which show signs of rot or disease. Place your clean corms into a cardboard box or other well-ventilated container, and place them in a frost-free but cool location.
Check the corms regularly over the winter and throw out any corms which have begun to rot.
Of course, you may also simply grow gladioli in containers and move the containers under cover when frost threatens.
Every few years, in autumn, it is best to divide mature Gladioli clumps.
There are two main reasons for this –
The first reason is to avoid congestion. When gladioli clumps become congested, the plants will be weaker, and flowering may reduce considerably. The plants may even stop flowering altogether.
The second reason is to propagate new plants. Corms can be split from the clump to create new plants for a different container, or a different part of your garden.
Gladiolus bulbs, or corms, can provide you with colour and interest in your garden over a number of years to come, as long as you place them in the right places and care for them correctly. So Gladioli can be a great choice for a long-lasting, beautiful garden.
A permaculture garden designer, sustainability consultant and freelance writer, Elizabeth works as an advocate for positive change. She aims to inspire others to reconnect with nature and live in a more eco-friendly way. She also tries to practice what she preaches as she tends her own forest garden, polyculture beds and polytunnel. See her personal website here.