Verbena is a vigorous, long-flowering plant that provides colour in shades of purple, red, lavender, pink or white. Verbena may be annual or perennial and may be trailing or upright, depending on the variety. Plant verbena in a flowerbed, along a border, garden path or in a patio container. Annual verbenas benefit from cutting back occasionally throughout the growing season, but perennial verbenas need a bit of extra attention in autumn and spring.
Late spring and summer
Verbena needs a light pruning after the first flush of blooms fades in late spring. Without pruning, the plants produce very few blooms for the rest of the season. Prune with garden shears or a weed strimmer, removing old blooms and one-fourth of the growth from the top of the plant. Don't trim down so far that you remove the main stems of the plants. Pruning rejuvenates the plant, and another full flush of blooms appears in two to three weeks. Repeat at least twice throughout the summer to keep the plant blooming until autumn.
Trim verbena lightly in autumn, removing only enough growth from the top of the plants to leave your flowerbed looking neat and tidy until spring. Too much pruning in autumn makes the plants vulnerable to damage and loss during winter freezes. The dead tops also help keep the soil moist throughout the winter.
Cut verbena back nearly to the ground as soon as new growth appears in spring. Cutting verbena back in spring removes the dead and frozen plant tops and readies the plant for new spring growth. Spread 2.5 to 5 cm (1 to 2 inches) of mulch, such as shredded or chopped bark, on the ground around the plant to prevent moisture loss and keep weeds in check.
Water verbena deeply after cutting back, including after the final trim in autumn. Apply fertiliser every time you trim the plants, except for the last pruning in autumn. Use a light application of a balanced, general-purpose garden fertiliser. If your verbena is planted in a container, apply a liquid or water-soluble fertiliser. Apply either fertiliser according to the specifications on the container. Avoid fertilising verbena in late summer or autumn, because fertiliser produces tender new growth that is susceptible to freezing once winter temperatures set in.