UNITED STATES—Early spring bulbs that went into their gardens last autumn are now blooming. Some are already done. Some summer bulbs should begin to bloom as the last spring bulbs finish. A few of them might bloom as late as autumn. Ultimately, like the earliest of spring bulbs, all eventually finish. As they do, their deteriorating flowers will necessitate deadheading.

Deadheading is simply the removal of deteriorating blooms. For many species, it diverts resources from fruiting into other growth. Many species can utilize diverted resources for subsequent bloom. Many become more intent on blooming again after deprivation of any prior fruiting. Spring bulbs instead utilize all their diverted resources for new bulb growth.

For spring bulbs, it is the most practical response to deadheading. Most bloom only once annually. Therefore, they cannot divert resources directly to subsequent bloom. Instead, they prioritize vegetative growth of bulbs to grow and bloom for the next spring. They are patient. Reproduction remains their priority. They merely regroup before another attempt.

Deadheading may accomplish more than merely neatening the garden.

Because of extensive breeding, many spring bulbs cannot produce viable seed anyway. Of course, this does not prevent them from trying. Even seeding or fruiting structures that contain no viable seed can be unappealing. For them, deadheading is merely aesthetic. Some complicated hybrids that might produce viable seed are unlikely to be true to type.

Elimination of viable seed that is not true to type is as practical as it is aesthetic. Without deadheading, such seed can grow into feral progeny. Such ferals may be more similar to remote ancestors than to their direct parents. They can be aesthetically inferior, but more prolific. Eventually, less desirable feral bulbs may displace their more desirable parents.

Because they are small but abundant, some freesia avoid deadheading. Resultant ferals are more fragrant but less colorful with pale white bloom. They are more prolific, so might eventually displace their parents. Common grape hyacinth and snowflake are too florific to deadhead but are true to type. Actually, they can become invasive in some situations. Montbretia are very likely to be invasive.

Highlight: Bearded Iris

There may be no other flowers that exhibit such a diverse range of floral colors. Bearded iris, Iris X germanica, classifies as a hybrid of Iris pallida and Iris variegata. The genus of Iris derives its name from the Greek word for rainbow. As the name implies, it includes all colors of the spectrum. Floral form, height and, for some, fragrance is also quite variable.

About 60,000 cultivars of bearded iris are supposedly documentable. It is difficult to estimate how many lack documentation. The smaller miniature cultivars are only a few inches tall. The tallest cultivars may grow four feet tall. Although they classify as summer bulbs, they are fleshy rhizomes that bloom for spring. Some will bloom again for autumn.

Bearded iris multiply whether or not anyone wants them to. Their rhizomes branch in two directions after bloom. Besides that, side shoots develop randomly from plump rhizomes. Congested rhizomes may bloom less. Division during summer promotes bloom. Division may happen annually or every few years. Bearded iris prefer sunny and warm exposure.

Tony Tomeo can be contacted at tonytomeo.com.