Late Summer Garden Cleanup

The appearance of a perennial garden naturally evolves and changes with the seasons. By the time late August rolls around, many perennial flowers have run their course, leaving some old flower stalks begging to be cut down.  Now is the time to tidy up your perennial garden to keep it looking good and going strong into the fall.  But, before you get out your clippers and start cutting, there are often reasons to leave some spent flower stalks in place a little longer.  This is particularly the case if you have areas in your yard designed for wildlife habitat or for pollinators.  Some things to consider:

• Overall appearance of a garden matters, so begin cutting down old flower stalks of plants no longer in bloom (e.g., hosta, Shasta daisy, yarrow, day lily, astilbe, iris) or those beginning to flop. At the same time, cut out any spring flowering plants whose foliage has discolored (turned yellow or black) and stopped growing (e.g., bleeding heart, peony).
• Consider leaving stalks that attract pollinators until they have completely finished blooming (e.g., phlox, lobelia, monarda, liatris), because hummingbirds, butterflies, dragonflies, and bees are attracted to them as long as there is any remnant of flowering material.
• Consider leaving seed-bearing plants (e.g., purple cone flower, black-eyed Susan — pictured above) after they have stop blooming, because they attract goldfinches and other small birds into the garden.  Any seeds generated from spring-flowering plants (e.g., columbine, zizia) have already been taken by birds weeks ago, so their stalks may be cut down any time.
• Leave garden milkweeds (e.g., butterfly weed, swamp milkweed) in place well into the fall, because they are hosts to monarch butterfly caterpillars, whose populations are threatened and declining.
• Continue to deadhead roses, butterfly bushes, and trumpet honeysuckle (Lonicera semperivirens) to encourage secondary blooms, which will extend their support of butterflies and hummingbirds.
• Many shrubs can still be lightly pruned if they appear unruly and need some reshaping. Avoid pruning spring-flowering shrubs that have already set their flower buds for next year (e.g., rhododendron, azalea, viburnum, pieris, cherry laurel, camellia).