The Euonymus genus has 175 species. Depending on species, they can grow as shrubs, ground cover or climbing vines. Euonymus varieties are prized for their foliage. Pruning helps to maintain the shape of the shrubs and keeps the foliage looking full. Without pruning, Euonymus can become leggy with long, sprawling vines and sparse leaves. Late winter or early spring is the best time to trim Euonymus shrubs. Pruning during the summer growing is beneficial in some circumstances. Late summer, fall and early winter trimming are not recommended.
The two emerald varieties of Euonymus are Emerald Gaiety and Emerald 'n Gold. Both are members of the species Euonymus fortunei, commonly known as wintercreeper. These low-growing shrubs are sometimes used as a ground cover on slopes or as a climbing vine. The Emerald Gaiety variety has white-edged green leaves. The leaves of the Emerald 'n Gold variety are green edged with gold.
Wintercreeper acts as a ground cover when allowed to spread or it can be maintained as individual low-growing shrubs. The shrubs will climb walls, fences and trellises when pruned to encourage branching. Gardeners can train these shrubs to climb by pinching off the stem tips of new growth. Pruning the terminal bud on a stem causes the stem to branch. This lateral growth pattern results in a fuller shaped shrub or vine.
Late Winter, Early Spring
During winter, emerald Euonymus shrubs are dormant. The shrubs store energy during this time and by late winter are gearing up for spring growth. There is less risk of freezing in late winter, compared with weather conditions earlier in the winter. Give wintercreeper a good trim in late winter to rejuvenate the shrub in preparation for new growth. Thin the branches during late winter or early spring to control spreading later during the growing season. Thinning promotes air circulation and inhibits mildew. The University of Illinois recommends annual pruning during late winter or early spring for wintercreeper grown as a climbing vine.
Trim wintercreeper during summer to control growth and preserve the desired shape for the shrub. Use a lawnmower with the blade on the highest setting to trim shrubs grown as ground cover. Use this method to trim shrubs once or twice during summer. The emerald Euonymus varieties have variegated leaves, but occasionally solid green leaves emerge. Trim branches with nonvariegated leaves when they emerge during the growing season.
When Not to Trim
Euonymus should not be trimmed in late summer, fall or early winter. Pruning during the growing season encourages new growth. New growth in late summer does not have enough time to mature before the onset of cold weather. Trimming later in the year leaves cut surfaces exposed to wintry conditions. Pruning in fall or early winter causes water loss from the branches that were cut.
- Washington State University, Skagit County Extension; Ask the Master Gardener, Euonymus; January 2007
- The University of Tennessee Institute of Agriculture; Best Management Practices for Pruning Landscape Trees, Shrubs and Ground Covers; Donna C. Fare
- University of Illinois Extension; Pruning Climbing Vines; Tony Bratsch