Most of us, male and female, know what it is like to be overdue for a haircut. One day you wake up and your hair is going in all kinds of new directions. Old cowlicks return like bad checks, curls straggle over earlobes or shoulders. Waves are in the wrong places, and creating the usual arrangement, which is as automatic in the morning as brushing your teeth, becomes harder to do.
Ornamental plants are just like hair. They get overgrown. This is especially true of annuals during the growing season.
Most people buy flats of annuals at the garden center. These plants are born in monstrous greenhouses somewhere else and cultivated under optimal conditions. Their life cycles are orchestrated so that they will bloom at specific times—some earlier and some later. That way garden centers have decent looking displays for the entire peak spring buying season. When you buy a flat of annuals, chances are at least some of the little plants will be in bloom, and most of the others will have well-developed buds on them.
When you take your flats of petunias or marigolds or snapdragons home and plant them, they will look terrific, albeit a bit small, in your beds. In about two weeks they will finish the first flush of bloom. This is the time when you cease being simply a plant custodian and start being a plant parent. You must deadhead your plants.
Some people are afraid of deadheading, which is silly. All you have to do is remove the spent flowers with your fingers. If you have ever cleaned a toilet or changed a dirty diaper or even oiled a squeaky hinge, the job should not make you squeamish. Even if you have done none of those things, you still should be tough enough to take it. Deadheading prevents the plants from setting seed, tricking them into thinking that they still have to fulfill the biological imperative by making more flowers.
While this flower-making process is going on, annuals will also engage in vegetative growth. Stems will get longer, and somewhat leafier. This process is wonderful for the plants, but not such a good idea for landscape display purposes. To keep your annuals neat, full and floriferous, you need to cut back the long stems by one third to one half. That way, the plants will put their energies into flower production rather than leaf and stem growth. The end result will be bushier annuals and a happier gardener.
Deadheading is also a must for roses. Some roses, especially the old-fashioned varieties, only bloom once a year. For those plants, deadheading is a matter of choice. If you want tidiness, go right out and pluck off all the dead flowerheads. If you want to make rose hip jam, or provide food for the birds, or simply enjoy the appearance of bright red or orange hips, then forget about deadheading. After the rose petals fall off, the bulbous green hips will become apparent. Eventually they will begin changing color, providing visual interest in the garden well into the fall and early winter.
Remontant roses, those that bloom more than once a year, need deadheading for the same reason that annuals do. As my remontant roses bloom,; I go out every day and pinch off the spent blossoms. At the end of the first flush of bloom, I trim the blooming canes back by about 1/3. Treated in this way, the more vigorous of my remontant roses, such as the English rose ‘Abraham Darby’ and the old standby ‘Gruss an Aachen’ have three or even four flushes of bloom over the course of the growing season. Since I like to have my cake and eat it too, I let hips develop after the last flush, so that the birds and I have something for the cold months.
There are some perennials, such as coreopsis, Gaillardia daisies and salvias, that will bloom again and again if they are deadheaded. These should be encouraged, like bright children, so that they will support you in your old age (or towards the end of the gardening season). Others, including black-eyed Susan (Rudbeckia), purple coneflower (Echinacea), trollius and various perennial members of the campanula clan, should be deadheaded for the sake of good garden order, not in the hopes that they will triumph over their essential natures and bloom again.
To deadhead repeat blooming plants is to triumph, just for awhile, over the ephemeral nature of gardening. It is one of the least harmful ways to fool Mother Nature.
by E. Ginsburg