How to Cut Back New England Asters for Winter

New England Aster Culture

• You'll get the most bloom and the healthiest plants by growing your New England aster in full sun and soil that drains well. Avoid crowding this imposing plant, since good air circulation is important in helping it avoid the fungal diseases to which it is prone, powdery mildew and aster wilt. Since they are developing buds through the heat of summer, keep them well watered during any hot, dry spells to keep the new growth coming and to prevent leaf drop on the lower half of the plant.

Late-Season Pruning

• New England asters can bloom from late August through October. Deadheading -- clipping off faded flowers -- can extend the bloom in areas where the plant isn't stopped by frost. Though the flowers are pretty, you may not be too thrilled by the way the rest of the plant looks by late fall if you didn't prune or stake it earlier in the season. New England asters often have no, or bedraggled brown, foliage on the base of the plant and a form that is splayed apart at the center and flopping over onto other plants by the time it blooms. While this is one reason to put it out of its misery with a pre-winter pruning, the primary reason for cutting back New England asters in the fall is to prevent self-seeding. Most New England asters in cultivation are hybrids and seedlings are unlikely to look like the parent plant.

Cleanup

• To tidy up a New England aster, all you need are a pair of clean, sharp pruning shears. Trim them back to 3 to 4 inches tall. Rake up and compost all of the debris to avoid overwintering insects and fungi. If your plant showed signs of aster wilt before it bloomed -- sudden yellowing of the bottom of the plant and wilting leaves -- dispose of the entire plant in the trash.

Other Pruning

• Cutting a New England aster back by one-half in late spring and again in early summer can prevent many of the issues the plant has with supporting its height and leggy stems. Cutting the front of the plant shorter can also provide a screen of young foliage to hide unsightly stems without losing the height of the main plant or delaying bloom. Thinning one-third of the stems from the base of the plant while it is young can also improve air circulation to stave off some fungal diseases.