Deadheading Conserves Resources

If not deadheaded, roses can put a lot of resources into production of seed and hips.

It takes quite a bit of effort for flowers to bloom. It takes even more effort and resources for pollinated flowers to produce seed and the fruiting structures that contain the seed. If the seed of certain aggressive plants get dispersed, we need to put even more effort into pulling up the seedlings. It just never seems to end!

Removal of deteriorating flowers, commonly known (even by those of us who missed that generation) as ‘deadheading’, can eliminate so much of this extra work. Not many plants benefit from deadheading; but most that do are really grateful for it. Others that do not care one way or the other simply look better without their deteriorating flowers.

It is of course impossible to deadhead large flowering trees or vast areas of ground cover. Regularly shorn hedges should never need deadheading because they never get the opportunity to bloom or develop fruit. Plants that are appreciated for the ornamental quality of their fruit should of course not be deadheaded.

Most roses get deadheaded as they bloom because the development of their fruiting structures, known as ‘hips’, takes enough resources to compromise subsequent bloom. Removal of these hips therefore promotes bloom. Only the few types of roses that are grown for their showy hips should not get deadheaded. Phlox, daisies, zinias, dianthus and all sorts of plants with long continual bloom seasons likewise benefit from deadheading.

Some types of iris that produce seed perform better with deadheading, not because they will bloom again during the same season, but because they can divert resources to vegetative growth (like rhizomes and foliage) that will sustain bloom during the following year. Most bearded iris (that do not produce seed) and lily-of-the-Nile do not seem to care if they get deadheaded, but are generally more appealing without their finished flower trusses.

Four o’ clocks can not be deadheaded without also removing developing flowers, so can only be allowed to bloom and throw their invasive seed all over the garden. It is easier to pull their seedlings later. We have a bit more control over crocosmia. Even though they do not need to be deadheaded, they are less invasive and more appealing without their scraggly brown stalks and seed capsules.

Deadhead Spring Bulbs After Bloom

Most spring bulbs are done blooming.

Fruiting warm season vegetables that are now in season, such as squash, tomatoes and beans, are more abundant with regular harvest. Plants that produce such fruit respond to their natural obligation to generate seed. Deprivation of the fruit that contains their seed stimulates production of more. Similarly, it is helpful to deadhead some flowering plants.

Deadhead grooming is a type of pruning, even if it does not involve pruning shears. It is, in simple terms, the removal of deteriorating flowers after bloom. For some plants, it only improves aesthetic appeal. For many others, it redirects resources from seed production into subsequent bloom, or vegetative growth that eventually sustains subsequent bloom. 

Now that early spring bulbs are finishing bloom, it is time to deadhead them. Most bloom just once annually, so without the distraction of seed production, will prioritize vegetative growth into new bulbs to bloom for next year. Many of the summer bulbs that bloom later bloom more than once annually, so divert conserved resources into subsequent blooms.

However, many cultivars of spring bulbs are too extensively hybridized to produce viable seed. For them, deadhead grooming merely eliminates unappealingly deteriorated floral carcasses, while their foliage continues to sustain the development of new bulbs for next year. The foliage of most deteriorates slowly through warming spring or summer weather. 

Some extensively hybridized modern cultivars are not sterile though. Some can produce feral progeny that are less appealing than the hybrid parents, but are vigorous enough to displace them. Deadhead grooming eliminates most or all of the unwanted feral seed. Of course, for wild grape hyacinth and snowdrop, seed can be left to develop and disperse.

Established colonies of feral freesias can be allowed to make seed for more of the same. However, hybrid freesia benefits from deadhead grooming to eliminate feral seed. Dutch iris, narcissus, daffodil, tulip, hyacinth and lily can also benefit from deadhead grooming, for a variety of reasons. Some are sterile. Some are not. Some get shabby. Some do not.

Deadhead To Promote Continued Bloom

Alyssum is too profuse for deadheading.

Deadheading is simply the removal of deteriorating bloom prior to the maturation of seed or fruiting structures. Besides diverting resources, it removes unappealingly deteriorated bloom, as well as unwanted or potentially invasive seed. Deadheading can be delayed if seed from particular flowers is desirable, (although some types are genetically variable).

It was time to deadhead spring bulbs as they finished bloom earlier last spring. Now it is time to deadhead some of the summer bulbs. It eliminates unsightly faded floral stalks of gladiolus, and diverts resources into developing bulbs. It eradicates invasive montbretia seed. For canna, it conserves resources to enhance subsequent bloom through summer. 

It is helpful to deadhead some types of annual bedding plants too. Marigold, zinnia, floss flower, pincushion flower and petunia should bloom better with systematic deadheading. Of course, all will continue to bloom without deadheading, but might be slightly subdued, with fading flowers. Modern sterile varieties that produce no viable seed are less reliant.

Fortunately, there is no need to deadhead alyssum, lobelia, nasturtium, moss rose, busy Lizzie or verbena. Their bloom is so abundant that it constantly overwhelms older bloom. Grooming tiny alyssum and lobelia flowers would otherwise be incredibly tedious. Moss rose, alyssum and nasturtium are pleased to self sow, but revert to simpler feral varieties. 

Some branched types of sunflowers produce several blooms on several separate stems. Others bloom with only a single flower on top of a tall single stem. If deadheaded prior to the maturation of their seed, the stalks of some single sunflowers generate a few smaller axillary flowers by autumn. This technique inhibits seed production, but prolongs bloom.

Deadheading Spring Bulbs Conserves Resources

What happens when daffodils finish blooming?

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.

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.

Deadhead To Eliminate Fading Bloom

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Deadhead finished daffodils to conserve resources.

The need to deadhead so early in spring is one of the few minor consequences of spring bulbs. Long before it becomes necessary to deadhead zinnia, canna and rose, the first flowers to bloom as winter ends are already finished. Many are those of spring bulbs. Their lingering deteriorating bloom can be slightly unappealing. What is more of a concern, is that some will likely try to go to seed.

The process of producing unwanted seed consumes resources that could otherwise sustain more useful growth. However, for spring bulbs that have finished blooming, production of seed for a new generation is more important than their own survival. That is why it is helpful to deadhead bulbs and many other plants after bloom. If deprived of seed production, they divert resources elsewhere.

Deadheaded narcissus, daffodil, freesia, lily and tulip store more resources into new bulbs, which they generate to bloom next year. Snowdrop and grape hyacinth cultivars that get deadheaded are not likely to get overwhelmed by their own feral seedlings. (It is neither practical nor necessary to deadhead crocus or big naturalized colonies of snowflake, feral snowdrop or feral grape hyacinth.)

While it is important to deadhead most spring bulbs after bloom, it is also important to not remove deteriorating foliage prematurely. After all, the foliage produces the resources that are necessary to generate healthy new bulbs for next year. Such foliage starts to slowly deteriorate immediately after bloom, but may linger for many months. Bulbs will shed their foliage when they no longer need it.

Until then, bedding plants or low perennials can obscure deteriorating bulb foliage as it falls over. Trailing gazania and dwarf periwinkle work nicely for shorter bulbs. If they get shorn low for winter, trailing plumbago, common periwinkle and African daisy can work nicely for taller bulbs.

Deadheading Promotes And Prolongs Bloom

90612thumbApril showers bring May flowers. May flowers make a mess. Well, some of them do. Most simply disintegrate and fall from the trees, shrubs and vines that produced them, and decompose into the soil below. Some might have needed to be swept off of pavement and decks. Regardless, most of us do not notice the very minor consequences for the majority of spectacular spring bloom.

However, there are some flowers that demand a bit more attention after they finish blooming. They linger after the show is over, and can look shabby as they deteriorate. Small ones can simply be plucked. Larger blooms might need to be pruned out. The process of removing deteriorating blooms is known as ‘deadheading’, and it is done for more reasons than just to keep plants groomed.

Plants bloom to produce seed, and the production of seed takes resources. Removal of seed structures not only diverts resources to more useful functions, but for many plants, it also stimulates subsequent bloom in response to interrupted seed production. They literally keep trying until they are able to produce viable seed, even if they must continue all season until late autumn dormancy.

Most plants that benefit from deadheading are perennials. Shasta daisy, black-eyed Susan, blanket flower, cone flower, yarrow, lavender and beard tongue (penstemon) bloom more abundantly and for a longer time with regular deadheading. The various lavenders, as well as other perennials that are comparably shrubby, are easily deadheaded by shearing after profuse bloom phases.

For bulbs and bulb like perennials that bloom only once annually, deadheading will not promote subsequent bloom during the same year, but conserves resources for the following year. Daffodil, lily, clivia, various iris and, during summer, gladiolus and dahlia, all appreciate diligent deadheading.

Petunia and marigold are two annuals that happen to bloom better with regularly deadheading. They bloom so profusely that deadheading can be quite a chore. Plants that can be invasive, such as salsify, should be deadheaded before dispersing seed.