Whether you’re growing the verbena plant in a hanging basket, as ground cover, a landscape border or in a container, the verbena care and maintenance is generally the same. They have little need for special growing conditions and aren’t fussy about soil requirements.
What they are fussy about is watering, feeding, pruning and keeping potential insect infestations at bay.
Verbenas can be prolific bloomers right through the flowering season, but the caveat is that they need regular maintenance to keep them healthy and flowering. A lapse in the care of the verbena plant at any point is usually irreversible as they tend not to recover well.
To get the most blooms from the verbena plant, care and attention needs to be a priority. This isn’t the type of bloomer you can plant and forget, relying on nature to meet the plant’s nutritional requirements.
Verbena plants need a smart watering technique, regular feeding with the appropriate fertilizer for the growing conditions and preferably a monthly pruning routine to get rid of spent flowers which will encourage new blooms.
An Overview of What’s Needed for Effective Verbena Care
Regardless the species of verbena plant you’re growing, they have little care for the type of soil, other than it needs to be well-draining. This is easily controlled if you’re growing trailing varieties in hanging baskets or even as a container plant, but used as ground covering of border plants in the garden, heavy clay soils may need to be lightened.
How to Lighten Heavy Clay Soils
If you find your garden soil is heavy on clay or has more rocks than soil, one way to lighten it is to add sand. That can be effective at improving drainage and air circulation, both of which are fundamental for verbena care.
However, there is a solution that is more effective, but requires ongoing maintenance and that’s to work in organic mulch. Up to six inches of mulch such as compost, wood chips or leaf mold can be added on top of the soil.
The advantage of using this is the clay soil is better at releasing moisture as it tends to hold water. That’s the reason you don’t want to be planting verbena plants directly in clay heavy soil. The increased water retention is likely to lead to root rot.
Mulch is an effective workaround, but the most effective is to raise your ground level by adding 8” to 12” of topsoil and planting directly into that.
The choice is yours on how you want to improve your soil. The simplest method is to add some sand but it’s still going to restrict air circulation. Working in 4” to 6” of organic mulch is effective but will need to be done regularly due to the material decomposing.
The method that’s most effective is to leave the clay soil as it is and pour over 8” to 12” of a quality topsoil as that’s enough to care for the roots without them working into the heavier soil.
How Often to Water Verbena?
The rule of thumb you may already be acquainted with for watering verbena plants is an inch of rain per week is the amount of water the verbena plant needs.
That’s correct but only to a certain extent. Every season brings with it an assortment of temperatures and some days of drought. During the dry spells is when you need to pay attention to the watering requirements.
The soil needs to be moist but never wet. There are a number of problems that can set in when verbena plants get too wet. Especially the foliage. Verbena favors watering from the base so the water (and fertilizer) is directly fed to the plant roots and kept away from the foliage.
Feed the roots and let them take care of the plants.
Regularly check the soils moisture. The top 1” of the soil should be moist – not soaking. Water from the base to avoid soaking the plant’s foliage.
In the warmer days of the summer, it’s best to check the soil early in the morning each day. Two signs that the plant will need a drink are when 1) the soil is dry to touch or 2) the foliage looks limp. In other words, it’s starting to droop rather than standing upright.
It is best practice to hydrate verbena plants in the morning so that the soil is drier by nightfall, making it less attractive to insects that can cause problematic infestations.
Fertilizer Requirements for the Best Verbena Care Possible
However, or wherever you’re growing verbena, they are going to need frequent feeding. You can either use a slow-release fertilizer every other week, or a water-soluble fertilizer applied monthly.
Which method is right for you depends on where you’re growing them. As ground plants, planted in an area of your garden that gets full sun for at least 6 hours a day, a balanced water-soluble fertilizer of 20-20-20 applied once monthly will be sufficient.
For container grown verbena or trailing varieties of verbena grown in hanging baskets, a slow-release fertilizer applied once every other week will provide the additional nutrients the plants aren’t getting from traditional ground soil.
How and When to Prune Verbena Plants
The real challenge for verbena care is pruning. It needs to be done early and followed up with frequent pruning to encourage new growth and when done right, it’s a good opportunity to give your plant a fuller shape too. Without regular pruning (at least monthly), verbena plants are likely to grow leggy, suffer from yellowing leaves and generally be unappealing.
Pruning is how to prolong blooming, even if it means cutting off flowers when they’re open. They only take two to three weeks to grow back in so it’s definitely advantageous to cut these back. The only thing to remember is to start early, preferably in early spring, but if you are a little later, trim the plant back by up to one quarter of its size and it will continue to bloom throughout the summer. The only risk there is of stunting the growth of verbena plants is if you cut it back over a quarter of its size.
Pruning verbena is done through three seasons. spring, summer and fall.
Starting in the spring is when most of the pruning should happen. This is the earliest opportunity to start pruning and the time taken here is what’s going to shape the future blooms throughout the summer.
Early spring is when to get rid of any leggy stems/stalks that look weak. Only keep the strongest. Where there is new foliage already growing, snip the stalk about ¼-inch above the leaf or bud. Where there’s no offshoots, the stalks can be trimmed back to just 2” above ground level. The only exception is for dead growth which will be dark brown. Those can be cut at ground level.
Speaking of dark brown stalks, the first pruning in early spring is also when to get rid of any part of the plant that looks weak. Look for signs of mold, discoloration, and any signs of weaknesses. You only want to keep the strong parts of the plant. Once the pruning is done, growth will be fairly fast so you can be aggressive in the first stage of pruning verbena plants.
By summer, the first blooms will have arrived with some flowers being spent already. Spent flowers can be deadheaded at any time and the sooner they are, the sooner the plant will focus its energy toward new flowering.
Regardless whether flowers are spent or not though, by the summer, they will need another rigorous pruning. Up to a quarter of the plant’s height should be trimmed whether or not it’s in bloom. In just a few weeks, it will be flowering again anyway so it’s only a few weeks’ sacrifice for blooms for the rest of the summer and into the fall.
Once the main pruning is done to cut the plant by a quarter of its size, the rest of the summer can be spent periodically trimming back spent flowers to encourage new blooms. Deadheading is best done throughout the summer by cutting around 2-inches below the tip of flower to both encourage new growth and to control height.
Fall verbena care is focused on getting the plant ready for the coming winter and involves deadheading. Even flowers that are drooping but aren’t already spent should be removed.
Once the plant is pruned right back to just the stalks, you can then add a protective layer of mulch over the soil to help insulate the plant roots from colder winter temperatures. Not all verbena species will flower next season but adding some insulation can help protect the roots against frost giving the plant a chance of re-blooming next spring.
It should be noted the deadheading only apples to the flowers by snipping roughly 2” from the tip of the flower. Not the base. Heavier pruning is best done in early spring so in the fall, only remove the flowers from the stalks and leave the rest of the plant until early spring the following season before cutting it back by up to a quarter of its height.