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Weed Control in Daylilies

Mark Czarnota, Ph.D., Ornamental Weed Control Specialist
Department of Horticulture, 1109 Experiment Street
Griffin, GA 30223

Daylilies, with their beautiful flowers and long bloom periods, are one of the most popular herbaceous perennials in the landscape (Figure 1). With growth being as quick as one year from seed to flower, just about every community has a mature daylily breeder group. Acres of daylilies are planted throughout the United States for both commercial and private use.

Figure 1. A beautiful creamy yellow daylily.

Unfortunately, like most garden plants, weed control in daylilies can be difficult. Established perennial broadleaf weeds can be extremely difficult to control, requiring special techniques in order to remove them. Fortunately, annual broadleaf and grassy weeds can be easily controlled with mulches and the judicious use of herbicides.

As with any garden plants, planting daylilies in a proper location is extremely important in establishing healthy plants. Mulches applied 2 to 4 inches deep help prevent weeds from germinating. Pine bark, pinestraw or shredded hardwood bark are excellent choices. Many herbicides are labeled for use on daylilies. Table 1 includes preemergent herbicides that control a large spectrum of broadleaf and grass weeds from seed.

Most of the preemergent herbicides listed in Table 1 are available in both granular and sprayable forms. Granular herbicides are more popular with homeowners because they require no mixing and are more forgiving when an application error is made. This list of herbicides does not control all possible weeds, however. There are no “silver bullets” when it comes to herbicides. Most of these preemergent herbicides or herbicide combinations will provide 80 percent to 95 percent control of the weeds from seed. Weeds will be encountered that are not controlled with preemergent herbicides, but most of these weeds can be easily hand removed. Home gardeners might find hand removal of weeds adequate as well as invigorating. Preemergence herbicides work only if they are applied before the weeds germinate. Most of the preemergent herbicides will provide excellent control when applied in the spring (February to March) and fall (September to October).

Several postemergent grass herbicides also are labeled for use in daylilies. These are listed in Table 2.

Grass herbicides are concentrates that are mixed with water and sprayed over the top of daylilies to control grasses that are actively growing. These grass herbicides have no preemergent activity, and will not prevent the germination of seeds. The herbicides listed are the ones available at the time this article was written. Herbicide labeling changes, so make certain you read and understand the label before using any pesticide. As herbicides go off patent, many third-party manufacturers may market herbicides under different trade names, so buyers must beware. Glyphosate, for instance, the active ingredient in Roundup^®, is now available from many suppliers under different trade-named products.

Broadleaf and other perennial weeds can be difficult to control in daylilies. Nutsedge (Cyperus spp.) and Florida betony (Stachys floridana) are two problem weeds with no selective over-the-top herbicides available to control them in daylilies.

Herbicides that contain the active ingredient glyphosate can be used for spot treatments to control problem perennial weeds that have failed to be controlled by hand removal or mulches. First, carefully separate the foliage of perennial weeds from daylily leaves. Avoid breaking any of the leaves or stems. Then lay the weed horizontally on bare ground or on a piece of plastic, and spray, sponge or paint a 5 percent solution of glyphosate (6 oz of herbicide/128 oz of water). Make sure that the glyphosate herbicide used to make the 5 percent spray solution contains 41 percent or greater active ingredient (glyphosate). Be careful to avoid contact of the herbicide solution with desirable daylilies foliage. If any of the herbicide solution contacts daylily foliage, immediately wash it off with water. The treated plants will begin to die in 10 to 14 days.

If weeds re-sprout, repeat the glyphosate treatment. A relatively new herbicide, Sedgehammer® (halosulfuron), provides excellent control of sedges (yellow and purple). It can be used to spot treat actively growing sedge plants around daylilies. Also, remember that your county extension agent is available to help you with any pesticide or plant culture questions.

Good luck controlling weeds in your daylily beds!

ATTENTION!

Pesticide Precautions

1. Observe all directions, restrictions and precautions on pesticide labels. It is dangerous, wasteful and illegal to do otherwise.
2. Store all pesticides in original containers with labels intact and behind locked doors. “KEEP PESTICIDES OUT OF THE REACH OF CHILDREN.”
3. Use pesticides at correct label dosage and intervals to avoid illegal residues or injury to plants and animals.
4. Apply pesticides carefully to avoid drift or contamination of non-target areas.
5. Surplus pesticides and containers should be disposed of in accordance with label instructions so that contamination of water and other hazards will not result.
6. Follow directions on the pesticide label regarding restrictions as required by State or Federal Laws and Regulations.
7. Avoid any action that may threaten an Endangered Species or its habitat. Your county extension agent can inform you of Endangered Species in your area, help you identify them, and through the Fish and Wildlife Service Field Office identify actions that may threaten Endangered Species of their habitat.

Trade and brand names are used only for information. Cooperative Extension, University of Georgia College of Agricultural and Environmental Sciences does not guarantee nor warrant published standards on any product mentioned; neither does the use of a trade or brand name imply approval of any product to the exclusion of others which may also be suitable.

Circular 867-13/October, 2006

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