It seems that almost every daylily either begins or ends its bloom season sometime in July, so what could be more appropriate than naming a daylily July’s Plant of the Month? I admit there was a time when I considered the daylily to be a pedestrian plant, probably because it seemed to be ever-present in yards, in gardening catalogues, in books, and in magazines. Now I appreciate that the reason daylilies are used so often is that they are so often useful: few plants are as tough or as tolerant. Then there are those marvelous strappy leaves–such a terrific counterpoint to elliptical or rounded or maple-shaped leaves. ‘Hyperion’ is an heirloom variety, a diploid dating back to 1925. It is a clear lemon yellow, has a delightful fragrance, and is a flower with presence: from its base to the tip of the flower, ‘Hyperion’ is typically 42″ (107 cm) high, and its width is approximately 36″ (91 cm) when fully mature. Its only drawback is that the scapes (the stem holding the flower buds) need to be removed after flowering; otherwise, the plants look unkempt. Some web sites that offer ‘Hyperion’ state that it is repeat blooming. Hyperion is not a re-bloomer.
My real love affair with daylilies began when I lived at the intersection of two gravel alleys. The alley weeds were determined to make their way under my fence and into my tidy suburban garden. Even sprinkling Preen along the strip of alley next to my fence didn’t seem to finish off some of the more persistent weeds, so I decided to bite the financial bullet and plant a daylily “hedge” just outside the fence. I knew that it was possible for desirable plants to crowd out unwanted weeds, but I needed a plant that was tolerant of dry, dusty conditions, and also a plant that would reliably colonize itself; happily, sunlight was not a problem (that’s probably why the weeds did so well). I chose the ‘Joan Senior’ cultivar, a nice creamy white, and within two seasons the weeds were agreeably crowded out.
Daylilies, of course, are not truly lilies, since they do not grow from bulbs; but the flowers do resemble those of lilies. Most of the horticultural literature suggests providing daylilies with a minimum of 6 hours sunlight per day. However, if you choose a mid-season daylily (one that starts blooming at the beginning to middle of July), the intensity of the sun, and its position directly overhead, means that many daylilies will still grow well in indirect light or with less than 6 hours of direct sun per day. Daylilies will grow in loam or clay, alkaline or acidic soil, and are drought-resistant once established. The one maintenance task recommended for daylilies is division, although I’ve noticed that my ‘Hyperion’ daylilies are still going strong after 6 years with no division. Still, if your daylilies are showing weak flower production in the center of the plant, I recommend the procedures in this article from the National Arboretum, with one caveat: ignore the Arboretum’s advice on the time of year to divide daylilies. For Hardiness Zones 5 and 6, daylilies should always be divided in the spring once 2″-3″ of leaves have emerged from the soil.
Daylilies have no real pests or diseases other than rust, which requires Patrinia as an alternate host (not a widely grown plant), and a virus called Leaf Streak, which seems to be somewhat cultivar dependent. According to an article published by researchers Holcomb, Owings and Broyle, at Louisiana State University, entitled “Reaction of daylily cultivars to leaf streak, 2006”, the following cultivars are susceptible (11%-25% of leaves infected) to Leaf Streak:
Black Eyed Stella, Bitsy, Chorus Line, Frankly Scarlet, Judity, Lee Bea Orange Crush, Lady Lucille, Lullaby Baby, Mary Todd, Miss Victoria, Mr. Clifford, Pardon Me, Persian Market, Pirates Treasure, Plum Perfect, Red Volunteer, Scarlet Orbit, and Star Struck.
The following cultivars are very susceptible (more than 25% of leaves with symptoms) to Leaf Streak:
Bayou Bride, Daring Dilemma, Frans Hals, Green Eyes Wink, Happy Returns, Major Blue, Miss Mary Mary, and Perfect Peach Glory.
Viruses can’t be cured. Your only protection is to buy plants from a very reputable grower. Daylilies can be expensive, but it isn’t worth trying to save a few dollars to receive a plant that will only have to be pulled up and tossed away. Besides, with a healthy plant, you can divide it every 3-4 years and have plenty more daylilies to add to your own garden or to give away to friends, so the lifetime cost of a quality daylily is actually lower by the number of future plants available.