Deadheading: it keeps flowers coming all season

Sunset, May, 1988

Deadheading: it keeps flowers coming all season

Planted in borders or between shrubs, colorful bloomers like dwarf dahlias,

Marigolds, and petunias add a cheerful note to summer gardens--if you give your plants the right care during bloom.

Of course, regular fertilizing and watering are vital for healthy growth and long bloom, but so is deadheading--removing flowers as soon as they fade.

Once annuals and perennials start forming seeds, they channel their energy toward that activity instead of producing more flowers. By picking off old blooms-- including the developing seeds--you can keep flowers forming all season long.

To find out just how important deadheading is, we ran an experiment last year in Sunset's test garden. We planted two six-packs each of 'Sweet William' dianthus, dwarf dahlias, marigolds, nicotiana, petunias, vinca, and zinnias. We regularly groomed half the plants of each type; the other half we left alone.

By midsummer, the dahlias we didn't deadhead had nearly stopped blooming, as had the dianthus, but the groomed plants kept producing a bounty of flowers. Later, the untouched marigolds, nicotiana, petunias, and zinnias also slowed down or stopped blooming. The only exception was vinca; both sets of plants bloomed equally well throughout the growing season.

It's easy to keep up with deadheading on plants with flowers that fade slowly, such as marigolds and zinnias. When you cut off a flower, but sure you remove the seed receptacle as well as the petals.

On flowers that drop their petals, such as dahlias and cosmos, you may mistake buds for seed heads. Look closely before you clip; buds, unlike seed heads, are surrounded by tiny or tightly furled petals. With plants that form masses of flowers, such an nicotiana and petunias, deadheading can be a tedious choire. If you don't want to spend time pinching off individual flowers, wait until mid- to late summer when plants are covered with seed heads. Shear them off all at once as if you're giving the plants a haircut (see photograph above). At the same time, fertilize to encourage new blooms.

Photo: Covered with seed heads, this dahlia plant has almost stopped blooming. Flowering plant in rear was deadheaded regularly

Photo: Our test plot, shown here in peak bloom, doesn't yet show benefits of deadheading; a month later, plants not deadheaded will be declining, but the deadheaded ones will still flourish

Photo: Pinch off the entire flower, as shown on this petunia. Be sure to include part where seeds form at base of petals

Photo: To encourage blooms, shear seed heads off plants that produce masses of flowers, such as these nicotiana, in mid- to late summer