UNITED STATES—Now that the various spring bulbs have finished blooming, or will soon, many will benefit from deadheading. The techniques are simple, and actually benefit many plants besides spring bulbs. In the most basic terms, deadheading is merely the removal of deteriorating flowers after bloom. Ideally, it should happen prior to the development of seed structures.
A most obvious advantage of deadheading is that it eliminates unappealing carcasses of finished flowers. This neatens the appearance of remaining foliage. The foliage of some spring bulbs shrivels soon after bloom, but remains intact through the process, to sustain development of new bulbs. It is easier to ignore without prominently shabby floral stalks.
Deadheading also conserves and redirects resources that would otherwise sustain seed production. Such resources can instead promote vegetative growth, including production of new bulbs to replace the old. Furthermore, depriving bulbs of seed provides an added incentive for vegetative regeneration. If unable to survive by one means, they try another.
Going to seed does more than consume resources.
Some bulbs are more reliant on deadheading than others. Grape hyacinth and snowdrop are too profuse with bloom for minor seed production to inhibit their performance. In fact, they produce viable and genetically stable seed, which could be an advantage if more of the same are desirable. Although seed production is limited, seed disperses extensively.
Dutch crocus are an example of sterile hybrids that are unable to produce viable seed, or waste associated resources on such efforts. Other extensively bred bulbs that are not so sterile may not be true to type. Consequently, their progeny are likely to be very different. Freesia do not require deadheading, but can produce feral seedlings with insipid bloom.
Lily, narcissus, daffodil, tulip and hyacinth are some of the popular spring bulbs that now are ready for deadheading. Summer bulbs and perennials will get their turn later. Canna, dahlia and perennials that continue to bloom through summer will be tidier, and perhaps bloom more abundantly with efficient deadheading. They need not wait until next year to express their gratitude.
Highlight: Grape Hyacinth
Are they reliably perennial or invasive? In ideal situations, old fashioned grape hyacinth, Muscari armeniacum, can get a bit too eager to proliferate and migrate. Not only do their bulbs divide efficiently, but their seed disperse beyond bulb colonies. However, bulbs do not migrate too rapidly for containment. Thorough deadheading inhibits seed dispersion.
Grape hyacinth provides some of the earliest spring bloom. Floral spikes of tiny rounded flowers do not get much more than six inches tall, but are delightfully abundant. The rich blue color is exquisite. Hybrids and other species can bloom with pale pink, pale purple, white, yellow, or various shades or tints of blue. The grassy foliage is somewhat rubbery.
If they do not migrate efficiently enough, established colonies of grape hyacinth are easy to divide in autumn. Of course, it will be necessary to mark their locations as their foliage dies back at the end of spring. Division is easier and faster than growing new plants from seed. If hybrids produce seed at all, it may not be viable. If it is, it may not be true to type.
Horticulturist Tony Tomeo can be contacted at tonytomeo.com.