Purpletop Vervain in March: monthly care

Purpletop vervain requires minimal pruning, but a single annual cut-back in March keeps plants tidy and encourages vigorous new growth. In colder areas or after a harsh winter, the top growth will die back completely; in milder gardens, some stems may remain semi-evergreen but will look tatty by late winter. In March, cut all stems down to around 10–15 cm above ground level using secateurs or hedging shears. You'll usually see fresh basal growth emerging at the base by this time. Removing the old stems makes way for strong new shoots and prevents the plant becoming woody or congested. If you garden in a particularly cold or exposed spot (zone 7a), consider leaving the dead stems standing until March as they provide some frost protection to the crown. Many gardeners prefer to leave the spent flower stems standing through autumn and winter. The skeletal structure looks attractive when rimmed with frost, and goldfinches and other seed-eating birds will feed on the seedheads. If you choose this approach, simply delay all pruning until March rather than tidying up in autumn. Deadheading during the flowering season is not necessary and generally not recommended. Verbena bonariensis blooms prolifically from July through to the first frosts, and removing spent flowers is impractical given the sheer number of tiny blooms. The plant will continue flowering regardless, and allowing seeds to form encourages self-sowing, which is one of its great assets in a naturalistic planting scheme. If self-seeding becomes excessive, simply hoe out unwanted seedlings in spring.