In cold winter climates such as Iowa, an annual chore is the removal of dead plant debris from gardens and landscape areas. Annual flower beds and vegetable gardens can be cleaned up after the first killing freeze in fall. The best times to cut back several perennial plants are listed below.
Most perennials, such as peonies, daylilies, and hostas, can be cut back in November after a hard freeze has destroyed the aboveground growth. If fall cleanup isn’t possible, remove the dead debris in early spring.
Many ornamental grasses provide color, sound, and movement to the winter landscape. Because of these winter features, cut back ornamental grasses in April in Iowa. Cut back the grasses to within 3 to 4 inches of the ground with hand shears, lopping shears, or hedge trimmers.
Asparagus foliage can be cut back to the ground after it has been destroyed by cold temperatures in fall. However, it’s best to allow the dead foliage to stand over winter. The dead debris will catch and hold snow. Snow cover helps protect the asparagus crowns from cold winter temperatures. Asparagus foliage allowed to remain in the garden over winter should be removed in late March or early April before spears begin to emerge.
Clematis cultivars can be placed into three groups based on their flowering characteristics. Some cultivars bloom on the current season’s growth. Others bloom on the previous year’s growth (old wood). The third group blooms on both old and new wood.
Clematis vines that bloom on the current season’s growth should be pruned back to within 4 to 6 inches of the ground in late winter/early spring. Wait until the vines begin to leaf out before pruning the other two groups of clematis. Prune out all the dead wood once the vines begin to leaf out. The destruction of much of the old wood in winter will drastically reduce flowering in the last 2 groups of clematis
Links to this article are strongly encouraged, and this article may be republished without further permission if published as written and if credit is given to the author, Horticulture and Home Pest News, and Iowa State University Extension and Outreach. If this article is to be used in any other manner, permission from the author is required. This article was originally published on October 24, 2014. The information contained within may not be the most current and accurate depending on when it is accessed.