UNITED STATES—April 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.

Highlight: Shasta daisy

It just might be one of the most popular daisies nowadays, but Shasta daisy, Leucanthemum X superbum, is not a naturally occurring species. It was developed by Luther Burbank in 1890, as a complicated hybrid of four different species, one of which is of a different genus. Yet, it is somehow genetically stable enough to produce viable seed, although seed of cultivars is not true-to-type.

Shasta daisy is an herbaceous perennial that forms a substantial network of sturdy rhizomes that mostly stay close to the ground, with blooming stems that can get almost three feet tall. Primary bloom begins in late spring or early summer, and continues until autumn, either in minor subsequent phases or as sporadic bloom. Flowers are big classic white daisies with bright yellow centers.

Although it can survive neglect and lapses of watering, Shasta daisy prefers to be watered at least occasionally, and is much more appealing if flower stalks are pruned away as they finish. It likes full sun, but will tolerate a bit of shade through part of the day. Mature plants are easy to divide for propagation. If the odd aroma is not too objectionable, Shasta daisies are delightful cut flowers.

Horticulturist Tony Tomeo can be contacted at tonytomeo.com.