Foliage is nice, but flowers are the real draw for most gardeners. Perennials, which reappear on the same roots for a minimum of three seasons, seem to be an easy option, because you don't need to get down in the dirt as frequently as with the annuals you have to replace each year. The trade-off, however, is in how long the plants bloom. Where annuals flower until frost, perennials are largely seasonal, having blooming periods that last a few weeks or a month in a specific part of the season. While some perennials do have longer blooming season than others, you can make your favorites perform longer with consistent pruning.
Pinch out the growing tips on some or all of your summer to fall-flowering perennials in late spring to early summer. Removing the tips encourages bushier growth and delays bloom, so the plant produces more flowers, slightly later. Allowing some of the plant to mature naturally or pinching one plant a week after another of the same species staggers the bloom period.
Shear off early spring-blooming perennials by half their height with pruning shears after flowering to encourage new growth and reblooming. Spring-blooming perennials often flower again in summer, either in another flush of bloom or off and on, when cut back.
Snip individual flowers from summer blooming perennials that have lateral stems and multiple blooms, just above the first flower bud below the fading flower. This is called deadheading and encourages the plant to produce another flower instead of putting its energy into setting seed.
Remove the long flower stalks at the base with your hands or pruners when the perennial produces one flower or a spire of flowers with no lateral stems.
Cut branches of lateral-forming perennials that you previously deadheaded down to 2 inches above the basal foliage, the thick growth at the crown of the plant, when the second round of bloom fades. This can prompt another round of bloom, although flowers may be fewer and smaller. Even is flowers do not rebloom, it freshens the foliage, keeps it compact for the rest of the growing season and prevents self-seeding.
Water plants cut down to basal foliage well and gently aerate the soil around the plant with a hoe to help it recover from the drastic cut.
Things You Will Need
- Bypass pruners
- Pruning shears
- Allow some blooms to set seed if you want plants to self-sow or if the seeds attract desirable birds to your garden.
- Stop deadheading and cutting back in late summer to early fall to avoid encouraging growth that could be damaged by cold.
- University of Vermont Plant and Soil Science: Perennials -- Choosing and Planting
- The Well-Tended Perennial Garden; Tracy DiSabato-Aust
- The Master Gardeners: Tips on Summer Care of Perennial Gardens
- Sunset: Pruning Annuals and Perennials
- University of Minnesota Sustainable Urban Landscape Information Series: Pruning Perennials
- Missouri Botanical Garden: Leucanthemum x Superbum "Becky"
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