1. Q. How often do daylilies need dividing? What is the best technique to use?

A. Daylilies should be divided every three to five years, depending on how well they have grown. Division is best done in early spring, as new shoots begin to emerge, or in the fall after the plants are dormant. When dividing these, dig the whole clump. Separate by using two spading forks inserted back to back into the middle of the clump and then pried apart. This is less damaging to the roots than cutting, which injures a large number of feeder roots.

If you are going to replant in the same location, replenish the soil before planting with well-rotted compost and a fertilizer high in phosphorus for root development. Space plants at two feet apart--slightly less for dwarf cultivars.

2. Q. My neighbor is growing some daylilies with huge blooms that she said were tetraploids. What does that mean?

A. A tetraploid is an organism having four sets of chromosomes, the genetic matter that determines the physical traits of the organism. Humans have two sets, one from each parent, making us diploids. Most naturally occurring daylilies are also diploids. However, the chromosome count of some plants can be doubled by treating them with colchicine, an alkaloid obtained from the autumn crocus. Doubling the number of chromosomes in daylilies means four sets, hence a tetraploid.

Tetraploid plants often have larger, more intensely colored flowers with thicker petals. The foliage is darker green and more vigorous. Today's tetraploid daylilies that have been bred for extended bloom are more persistent bloomers than most diploid daylilies bred for long bloom periods. They are well worth having in any flower garden, though they may have fewer flowers and are slow growing. They will not require frequent division as do other daylilies.

For additional information on growing daylilies in South Central Texas, see the publication Q&A for Texas Daylilies.

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