Don’t let the dainty flowers fool you, tall verbena (Verbena bonariensis) is one hardy and vigorous plant. Although it can grow up to six feet tall, tall verbena (also called purpletop vervain) remains wispy enough to allow you to see what’s behind it. This feature makes it one of the best filler plants for any garden, as it seeds itself between other plants without squeezing them out.
Verbena bonariensis is native to South America and flourishes in sunny, warm gardens. The plant grows groups of lance-shaped basal leaves, and the stems are long, slender, and square. The violet-colored flowers form in clusters and start blooming in mid-summer, continuing on until the first frost.
Classified by herbalists as a plant with "cooling" tendencies, verbena is commonly used in Europe as a remedy for headaches or abdominal ailments.
When to Grow Tall Verbena
It's hard to find seedlings or starters in the tall verbena variety, as the plant only grows as a perennial in USDA Hardiness Zones 7 and higher. For this reason, you can start your own seeds indoors in a sunny window in the early spring. However, you don’t gain much by starting early and indoors, so some gardeners simply prefer to scatter seeds in the early spring, after the snow has melted. Planting in the fall works too, in some climates.
Equipment / Tools
- Gardening gloves
- Tall verbena seeds
- Compost, peat, or another soil amender (if needed)
Choose a Location
Choose a sunny location in your garden to plant verbena. If you're growing it as a perennial, make sure the location you choose will accommodate this big plant that reseeds itself year after year.
Amend the Soil
If the location you choose needs additional nutrients (you can test the soil's pH to see) or if the soil is compact, spread a bag of compost and peat over the entire area and incorporate it with the existing soil by raking it in.
Spread the Seeds
Sprinkle verbena seeds in the designated area. You do not need to cover them. However, some gardeners feel more comfortable sowing seeds separately into shallow holes and then raking to cover them gently.
Water the Area
Use a garden hose to water the planted area. Keep it continually moist until the seeds sprout. Germination can be slow and irregular.
Pinch the Seedlings
Once the seedlings are well-established with several leaf sets, pinch back the end set to maintain a compact plant. Do this several times early in the growing season.
Water the Plants
Continue to hand-water your plants or set up a timed sprinkler to do it for you. Make sure that the soil dries completely between each watering.
Maintain Your Patch
Tall verbena will continue to propagate itself for years to come. If you prefer to keep the mound compact, pull new seedlings each spring as they sprout up from volunteer seeds.
Tall Verbena Growing Tips
- If sowing seeds in the fall, do so before the first frost and follow the same instructions. You can skip the task of watering if it's a rainy spring with ample rainfall.
- To achieve a showy display, make sure your soil contains plenty of organic matter. Tall verbena is not particular about soil pH, yet it flourishes best in the neutral range of 6.0 to 6.8.
- Tall verbena shines when used in a mixed border and allowed to grow between other plants. However, when planted alone in large swaths, it makes a great centerpiece to a cottage garden, as well.
- Tall verbena's purple flowers pair best alongside perennial plants with yellow flowers or foliage. It mixes equally well with other cottage flowers, like cosmos.
- The flowers of Verbena bonariensis may be tiny, but they contain enough pollen and nectar to attract hummingbirds and bees, making this species a great choice for pollinator gardens.
- Perennial tall verbena can also be divided to make additional plants. The ideal time to propagate the plant from cuttings is in early spring, as well.
- Once established, tall verbena is very drought resistant, but it grows best with an inch, or so, of water, a week and perennial plants will appreciate a dose of food early in the spring.
- This low-maintenance plant does not require deadheading. However, you'll have a showier display if the spent flowers are pruned throughout the season.
- Annual verbena plants are rarely bothered by pests. But, perennial plants can become susceptible to aphids, slugs, snails, spider mites, and whiteflies. Also watch out for powdery mildew, leaf spots, and rust, especially in humid areas.