How To Grow And Care For Verbena

Whether you choose a short or a tall variety, annual or perennial, vibrant verbena makes a stunning statement anywhere in the garden. From a carpet of lush foliage punctuated by velvety blooms to tall, wispy pops of color, these plants bloom from spring through fall. 

A diverse genus of flowering herbaceous perennials and annuals, verbena can be categorized into several different types: trailing, upright, moss, and annual. Verbenas grow moderately quickly and bloom in their first season, but may be short-lived. Those that trail reach only 1 ft. tall to 3 ft. wide and are typically annuals. Known for their vibrant colors, nursery displays are saturated with these verbena starting in early spring through fall. These low, spreading ground covers shine in rock gardens, on slopes, in borders, and in hanging baskets. Their dense mat of dark green foliage is punctuated by brilliant clusters of small, five-petaled flowers.

Upright varieties like Verbena bonariensis, or tall verbena, bring dramatic height to beds. They grow as tall as 3 to 6 ft. tall and 1 to 3 ft. wide. This light and airy giant provides a soft, flowing backdrop for a layered bed. Finally, the feathery foliage of moss verbena reaches 1 foot tall and 3 feet or even wider. Moss verbena adds a wispy element to a garden, especially when it is paired with more structural garden plants.

The best time to plant verbena is in spring or summer, though it may be planted in fall in the Coastal South. The flowers are excellent additions to pollinator gardens, the nectar attracting bees, butterflies, moths and hummingbirds.  Verbena is specifically known to attract the hummingbird hawk moth and pipevine swallowtail. Between their long bloom season and ability to stand up to sweltering hot weather, verbena is a welcome addition in any Southern garden.

Plant Attributes

Verbena Care

Versatile verbena come into their own quickly in the garden and bloom profusely in their first year, unlike some other perennials. Plant them in full sun using well-drained soil with a covering of mulch to retain moisture. Water regularly until established. Verbena can tolerate heat and drought but will bloom best with some supplemental watering in the hottest part of summer.

Light 

All species of verbena thrive, grow, and bloom best in six to eight hours of full sun. Planting verbena in low light can lead to powdery mildew and other problems.

Soil 

Verbena adapts to most soils as long as they are well-draining. Many varieties will do fine in poor, somewhat sandy soils. Those planted in very sandy soil will benefit from the addition of compost or fertilizer. Clay soils should be amended to improve drainage. The garden verbena sold as annuals can also be grown in containers in a well-draining potting mix.

Water 

Water regularly while plants are getting established, keeping the soil lightly moist for the first couple of weeks. Otherwise, allow the soil to dry out between waterings. Too much water may cause root rot or powdery mildew. Once established, verbena can be somewhat drought tolerant, but the plants will produce more blooms when they receive an inch of water each week. Water deeply once a week when the plants don't receive adequate rainfall. Avoid getting the foliage wet when you water.

Temperature and Humidity 

Most verbenas flourish in the heat and humidity of summer. In fact, many of the hybrid varieties have been specifically bred for heat-, drought-, and disease-tolerance. Rose verbena (V. canadensis) is a native perennial used as a parent for many hybrid garden verbenas. It is hardy in Zones 6-10.

Among the perennials commonly sold in nurseries, most are winter hardy in Zones 7 (tall verbena and sandpaper verbena) or 8 (moss verbena) and warmer. These self seed and have naturalized in parts of the South.

Fertilizer 

Verbena does well in soil with average or lower fertility, but a small boost can give you more blooms. Adding compost to your soil when planting will provide long-term nutrients to plants in garden beds. Alternatively, you can apply a slow-release, granular fertilizer formulated for flowers in late spring. Container-grown plants benefit from more frequent fertilizing. Use a liquid fertilizer once a month or sprinkle slow-release fertilizer in your pots according to package instructions.

Types Of Verbena

• V. bonariensis – Also known as tall or purple top verbena, this upright plant has airy stems that reach 5 feet high and are topped with delicate lavender flower clusters. Perennial in Zones 7-11, it handles many soil types and dry conditions. Meteor Shower® is a more compact cultivar that is less likely to set seed and escape from the garden.
• V. canadensis – Trailing or rose verbena spreads in a low mound, making an excellent ground cover, border plant, or hanging basket addition. This Southeastern native likes sandy soils and is hardy in Zones 6-10. Cultivars feature purple, red, pink, or white flowers.
• V. aristigera – Dainty clumps of blooms cover fine foliage on moss verbena, an excellent choice for borders, rock gardens and under sculptural plants. The 1-foot clumps of blue to purple flowers can spread to 6 feet wide. This South American native is hardy in Zones 8-10.
• V. x hybrida –Annuals in most locations, these compact plants come is a wide variety of colors and are primarily seasonal bedding and container flowers. They can be mounding or trailing and have purple, blue, red, pink, white, or even candy striped blooms. Look for heat-tolerant, mildew-resistant series like Superbena and Endurascape.
• V. rigida - Known as sandpaper verbena or slender vervain, this South American native grows to 2 feet tall and has ovate, toothed leaves and round purple flower clusters. Hardy in Zones 7-10, it does well in hot, sunny, dry borders.

Pruning

Many of the annuals are self-cleaning and don't require deadheading, but a light trim or haircut can encourage bushier growth and a new flush of blooms.

Prune perennial verbena by removing dead or fading flowers to prevent spreading by seed. Don't prune severely in fall, as this can lessen verbena's chances of surviving a cold winter. Wait until spring when new growth starts to emerge.

Propagating Verbena

Verbena can be propagated from tip and stem cuttings in spring or early summer (check your plant label first as patent-protected cultivars cannot be propagated). The soft green stems root easily in a light-weight, porous potting mix—but make sure to use stems that are not topped with flowers. You can also use semi-ripe cuttings from perennial verbena in late summer. These are firmer at the base but still soft and green on the tips.

1. Pinch or cut off non-flowering stems from side shoots. Trim each to be about 3 inches long and remove lower leaves from the stems, leaving one or two sets of leaves on each.
2. Fill small containers with moist, light potting mix.
3. Make holes in the potting mix with a pencil or chopstick (you can fit three or four cuttings in a 4-inch container. Dip the bottom tip of each stem into rooting hormone, then slip cuttings into the holes so that the leaves are just above the soil line.
4. Water well. Place a clear plastic bag over the top of the plants, making sure it doesn't come into contact with the leaves. Avoid direct sunlight, but place pots in a bright location. 
5. Keep soil moist, but don’t allow it to become water-logged. Roots should develop in three to six weeks, depending on how green the stems were.
6.  Remove the plastic bag once plants begin to root, but continue to keep soil moist. Transplant into the garden or a container once new growth appears and the plants are well-established.

How To Grow Verbena From Seed

Some varieties of verbena can be grown by seed by sowing indoors and transplanting into the garden after danger of frost has passed.

1. Sow seeds into a seed-starter mix, pressing into the top, but don’t cover them with soil.
2. Keep the seeds moist with a mister and cover them with clear plastic or use a seed-starting tray with a clear lid. 
3. To germinate, seeds should be placed in a warm and bright location for two to four weeks. 
4. Transplant into the garden or a container in two to four weeks when leaves begin to develop and after danger of frost.

Some hybrids are non-seeding. Most plants are readily available in different sizes at nurseries.

Potting And Repotting Verbena

Garden verbenas make great container plants and look beautiful planted in a mass or in mixed containers. Verbena can also be planted in hanging baskets to trail over the sides. When planting a mixed container, pair them with other flowers and foliage with similar low-water needs. Select a container with a drainage hole and use a well-draining potting mix. Place in a sunny spot and water after the top inch of soil dries out. Fertilize monthly with a liquid fertilizer for vigorous growth and lots of blooms.

Overwintering

Perennial plants will go dormant in fall and die back until spring. Don't prune plants severely in fall, which can reduce their chances of surviving winter. Wait until new growth appears in spring. Add a layer of mulch around the base of plants if you have cold winters. Perennial verbena does not always survive wet, harsh winters. Some gardeners collect seeds or stem cuttings in fall as insurance so they'll have verbena the following year.

If you experience heavy frosts, you'll most likely need to replace bedding verbenas the next spring. You can move containers indoors or dig plants up and pot them. But the plants will need at least six hours of direct sunlight or a grow light to thrive.

Common Pests & Plant Diseases

Overwatering or poorly drained soil can lead to root rot, powdery mildew, or gray mold. Verbenas don’t like wet feet and will develop these or other fungal issues if conditions are too moist or they are planted in areas with poor air circulation. 

Like any plant, verbenas can be subject to pests, though they don’t typically have specific known issues. Keep an eye out for damaging insects like aphids, spider mites, and whiteflies, and treat with insecticidal soap or neem oil. Verbena plants are deer-resistant.

How To Get Verbena To Bloom

Verbena blooms easily and for weeks at a time. Long dry spells can interrupt blooming, so make sure the plants receive adequate moisture. One good watering (or rainfall) a week is usually sufficient, but keep an eye on plants to make sure they're not drooping.

If they slow down in summer, mounding or trailing verbenas can be trimmed back by as much as 1/4 to encourage a new flush of growth and blooms. Fertilize plants if you have not already and water well. Blooms usually appear in two or three weeks.

Common Problems With Verbena 

Verbenas don’t suffer from any serious problems outside of pests or diseases caused by excess moisture. Inadequate watering or light can lead to these two issues.

Leaves Dry Up Or Die Back

Unless you've seen signs of disease, this is usually caused by a lack of watering. Verbena is moderately drought tolerant, but should receive some moisture weekly to remain healthy. Sometimes they need more, especially when planted in full sun in a very hot garden. Keep an eye out for wilting foliage and water any time you spot it.

Leggy Growth

Inadequate sunshine can cause leggy growth, but this phenomenon also is typical for mounding and trailing verbenas. You may need to shear the plants by 1/4 a couple of times during the growing season to rejuvenate them.