|Official Plant Name||Verbena Bonariensis|
|Common Name(s)||Purple Top, Argentinian Vervain|
|Plant Type||Perennial Flower|
|Native Area||South America|
|Foliage||Sparse, oblong leaves|
|Flowers||Spikes or panicles of small purple flowers|
|When To Sow||March, April, May|
|Flowering Months||June, July, August, September|
|When To Prune||March|
Exposed or Sheltered
1.5 – 2.5M
1.5 – 2.5M
June – September
Most Soil Types
Moist but well drained
Verbena bonariensis is a perennial purple-topped plant that not only looks great but is also quite easy to grow and look after.
Adding these plants to your garden will help to give it a unique look and add plenty of colour.
You can buy verbena bonariensis in containers or grow them yourself from seeds. Each approach has its advantage, but providing you take care of your plants properly, they should thrive and last for many years regardless of which option you choose.
Below is a full guide to verbena bonariensis that includes its background and origins, growing and pruning tips, when to plant it, common pests and problems and frequently asked questions.
Let’s begin by looking at the background of the species…
Background & Origins
Verbena bonariensis is part of the verbena family and goes by many names, including purpletop vervain, tall verbena, Argentinian vervain and pretty verbena.
It’s native to South America, but today it is grown in many different parts of the world.
Because of its propensity to self-seed, it is considered an invasive species in some areas. For example, in Washington state, it’s on the invasive species list. There are also certain places where it’s considered to be a weed, including New Guinea and Fiji.
Feeding, Care & Growing Tips
When growing verbena bonariensis, you can either buy plants that have already been established or grow them yourself from seed. Let’s look at planting established plants first…
Before planting, you should make sure you have a good spot for them. They do best in full sunlight but can also tolerate partial shade, so bear this in mind when picking your spot.
When planting them, be sure to dig a generous sized hole to accommodate the roots and it’s never a bad idea to use a good quality fertiliser after planting to encourage the best growth.
If you’re growing from seed, then you have a couple of options. You can either plant them directly in the soil or grow them in containers first and plant them when they’re more established.
If you plant the seeds directly, then the best time to do this would be in April/May. This will give them plenty of time to get established and they’ll benefit from getting direct exposure to the sun during the hottest period of the year.
If you want to grow them indoors before planting, you should sow them around 3 months before you plan to plant them. The benefit to growing indoors is that you can grow your plants earlier, since they’ll be protected from the frost during the winter.
As for its water requirements, verbena bonariensis should be watered once a week. Make sure to soak your plants well but don’t let them sit in oversaturated soil for too long since it can cause the roots to rot. To avoid this, you should water them on sunny days and water as early in the day as possible so there’s plenty of time for the sun to evaporate the water.
It’s a good idea to add a layer of mulch to your plants in the autumn. This will help to protect the roots during any frosty periods in the winter.
Pruning Verbena Bonariensis
Although verbena bonariensis plants don’t require too much pruning, it can help to encourage new growth, so it’s not a bad idea to lightly prune them as you see fit.
The best time to prune your plants is in early spring. This will ensure that new growth comes through and your plants will be looking at their best for the summer.
When To Plant Verbena Bonariensis
The best time to plant verbena bonariensis when you’re planting them directly in soil would be in early spring. As mentioned above, you can grow them earlier than this if you have them in containers.
Habitat & Growing Conditions
Verbena bonariensis are native to South America and can be found in many countries throughout the region, including Brazil and Argentina.
They enjoy a sunny climate, although they can still survive in colder climates, particularly as they self-seed so well.
The Benefits Of Growing In Your Garden
Below are some of the main benefits of growing verbena bonariensis in your garden –
Many people want to add more colour to their garden and verbena bonariensis are a great choice of plant to do this. With its vibrant purple flowers, it will stand out even amongst other colourful plants.
Verbena bonariensis plants will also attract butterflies and other pollinators to your garden. This is beneficial as they will help to pollinate your plants and beautify your garden.
Works great with other plants
Another great benefit of verbena bonariensis is that it looks great when used with other plants, especially colourful perennials. Mixing it with plants of other colours makes it very easy to brighten up your garden.
Propagating often isn’t necessary because these types of plant self-seed naturally, however you can propagate them yourself very easily using cuttings in containers.
The best type of stems to use would be those that look healthy but don’t have any flowers or buds. Prepare a container by packing it with some good quality soil and then plant the cutting into it. You should make a hole that’s roughly 2/3 the size of the cutting when planting. Also be sure to water it well immediately after planting.
Although verbena bonariensis generally enjoy the heat, it’s important that you don’t leave any cuttings in direct sunlight. Instead, you should find a partially shaded area and ideally use a propagation mat, so you can control the temperature.
You should regularly check on your cuttings to make sure they’re thriving. You should only water them when the soil feels dry and it’s better to use a spray bottle rather than pouring water into it, since it’s very easy for the soil to become overly saturated.
After 3-4 weeks, your cuttings should have taken root. To check if this is the case, you should gently pull them at the base. If you feel resistance, then they have taken root.
You should wait another month or two before planting them outside. Be sure to pick a good spot, with plenty of space that gets at least some direct sunlight during the day.
Common Diseases & Problems
In general, verbena bonariensis is resistant to diseases and pests, but there are certain problems it can suffer from. Below are some of the most common pests and diseases that it can be affected by, including how to deal with them.
Powdery mildew is a common type of fungus that affects many plants. It gets its name from the fact that infected plants develop a layer of mould on their leaves that resembles powder.
If you notice any plants that are affected by powdery mildew, you should remove and destroy them, since it can spread very easily.
Powdery mildew thrives in moist conditions. Knowing this will help you to take steps to prevent it from appearing in the first place. Firstly, you should make sure that there’s plenty of space between each plant. This will help to improve circulation.
You should also take care when watering your plants to ensure you don’t get any water on the leaves. This is very often why powdery mildew develops. It’s also a good idea to water your plants earlier in the day, so there is plenty of time for it to dry out in the sun.
Leaf spot manifests by causing the leaves of infected plants to develop small red/brown spots. Not only does it look unsightly, but it also affects a plant’s ability to photosynthesize properly.
If you notice any plants that are affected by leaf spot, then you should immediately dig them up and destroy them. As for avoiding leaf spot, the same advice for powdery mildew applies. You can treat less severely infected leaves with a fungal spray too.
Rust gets its name from the fact that infected leaves develop reddish/brown spots. If you catch it early, then it’s usually not too much of a problem and you can simply pick off any leaves that are affected. You can also use a fungicide to treat rust.
However, if it’s more widespread, then it’s usually better to get rid of the plant to prevent it from spreading to others.
Pests usually aren’t a problem for verbena bonariensis, but spider mites can sometimes be an issue. Not only do they pierce the leaves of plants, but female mites can lay many eggs, which hatch very quickly.
If you notice spider mites on your plants, then you should spray them with water or use a good insecticide.
Aphids can also be a problem for verbena bonariensis, although they’re quite easy to get rid of. You can simply spray them with water to remove them from the leaves of your plants. It’s also a good idea to encourage insects that feed on them to your garden, such as ladybirds.
Scale infestation causes problems for plants for a couple of reasons. Firstly, it will make it difficult for affected plants to photosynthesize and therefore affect their growth. It can also cause plants to lose their leaves when it’s more serious.
Using a good fungicide can help to keep plants free of scale, but treatments may need to be done regularly to ensure you kill off any remaining eggs.
Frequently Asked Questions
Should I pinch out verbena bonariensis?
Pinching out verbena bonariensis when they’re young will encourage them to branch and give them a more pleasing appearance, so you certainly shouldn’t be afraid to do this when you think it’s needed.
How far apart should I plant verbena bonariensis?
It’s a good idea to leave approximately 10 inches between each plant. This will ensure they each get enough moisture when you water them, and that air circulation is good too.
Are verbena bonariensis plants perennial?
Yes. Once you’ve planted verbena bonariensis, you can expect them to last for several years, providing they’re properly cared for.
What are the best soil conditions verbena bonariensis?
Verbena bonariensis plants do well in soil that’s moist and well-drained. They can also do well in chalky and clay soils. Using fertiliser and mulch in the autumn/winter can also help to make the soil conditions better and ensure they’ll thrive.
How often do you need to water them?
How often you need to water your plants will vary depending on the season. Spring would be the best time to plant verbena bonariensis and during the hotter periods in spring/summer, you should water them around once per week, taking care not to cause the soil to become waterlogged.
Is it better to buy plants or grow from seeds?
A lot of people who are interested in growing verbena bonariensis in their garden are curious whether it’s better to buy plants that are already established or growing from seeds.
The obvious benefit of buying plants that are established is that you can get the benefit of them immediately and can add colour and interest to your garden without having to wait for them to grow. Providing you get them from a quality supplier, you also know that they will be healthy and have been grown in optimal conditions.
Growing from seed has its own advantages too though. When growing from seed, you can control the type of soil and fertiliser used as well as how often they’re watered. There’s also a satisfaction that comes with watching your flowers thrive over the weeks and months.
Chris loves the outdoors and exploring nature. He is a freelance writer and has written extensively on subjects including travel, DIY and gardening.