Gardening with Gary

Gardening Advice from an Expert

Day Lilies

Sharon writes~
What is the best time of year to divide Day Lilies, spring or fall?

A. Day lilies can be very vigorous growers, often doubling in number from year to year to the point that they really should be divided every three to five years to continue good blooming. I have found that the late summer is an excellent time of the year to separate and transplant clumps of daylilies. By doing it at that time, it gives them an opportunity to settle in before shorter days and colder fall temperatures set in. Also by moving them in the early fall as opposed to the spring, they actually seem to bloom better.

There is really nothing to dividing day lilies. Just carefully lift the clumps with a sharp shovel and gently remove the soil from the roots so you can begin to see the individual plants. With a knife, separate each plant and remove any foliage that appears dead or diseased. One clump can produce up to ten plants. Cut off the foliage at about half and they are ready for transplanting back into the garden. Space them about 10-12" apart, put them in full sun and keep them well watered until they're rooted in place.

For maximum increase, simply dig up a clump and break off individual new shoots together with some root. If you do not need such a rapid increase, but want to obtain large clumps quite quickly, divide the plants into 2-4 pieces and replant right away into the garden. If the clump is so tight that it is difficult to divide, then you can cut your way through with a sharp knife or even chop the root with a garden spade.

Another method is to insert two forks back-to-back into the clump with the rear of their prongs touching and the handles about 1-2' apart. You then bring the handles together and this levers the clump apart.

Plants can be a bit slow to settle down after division and it can be a year or more before they really get going again, though they will soon make up for the lost time. One way of dividing a clump without the need to dig it up is to gently tease away young shoots from the outside of the clump. You will normally have to excavate a small amount of soil to make sure that you get some roots with the shoots. Pot them up and then plant out when well established, usually in mid summer. This form of division is especially easy with those species that have running roots.

Assistance from P. Allan Smith and SCS Leeds

Shulamit writes~
Several of my daylily plants have developed yellow leaves. This has also happened to some of my oriental lilies. They are getting plenty of sun and are not being overwatered. They are getting ready to bloom, so all seems well except for the leaf color. Can you please help solve this mystery?

A. Apply a high nitrogen fertilizer weekly according to the directions. This will green up the foliage but not interfere with the blooming. After 6 weeks, switch to a general 20-20-20 fertilizer so that flowering will continue throughout the season. The leaves of most daylilies are not known for a deep dark green color; more of a medium green color, but definitely not yellow. A good well-aged organic mulch surrounding the plants to a depth of 2" will keep the top roots moist during the heat of summer and supply good nourishment.