How to Kill Daylilies
The daylily is a hardy perennial plant with an unstoppable tuberous root called a rhizome. Though many gardeners relish the beautiful orange and yellow blooms of the daylily, the plant can turn into a wild nuisance and spread into unwanted areas. Digging up a patch of wild daylilies—or ditch lilies—is back breaking work and may not be enough to kill them completely. Any segment of daylily root left behind can spawn new growth. Killing unwanted daylilies takes patience and a time, but it can be accomplished.
Kill Unwanted Daylilies
Mow the area where the daylilies you want to kill are growing. Set the mower blade to its lowest setting to remove as much of the plant growth as possible. If the daylilies are growing in a ditch or hillside, you may need to use a string trimmer/weed whacker instead.
- The daylily is a hardy perennial plant with an unstoppable tuberous root called a rhizome.
- Digging up a patch of wild daylilies—or ditch lilies—is back breaking work and may not be enough to kill them completely.
Cover the area with a plastic weed barrier. Be sure to cover the entire area and a couple feet beyond to keep the unwanted daylilies from receiving sunlight. Stake down the weed barrier to keep it in place. Alternately, an inch-thick layer of newspaper can be used instead of store-bought weed barrier. Wet the newspaper to keep it from blowing away.
Cover the entire area with a foot of mulch. This will further prevent sunlight from reaching the unwanted daylilies and effectively kill the plants.
- Cover the area with a plastic weed barrier.
- Be sure to cover the entire area and a couple feet beyond to keep the unwanted daylilies from receiving sunlight.
Leave the mulch in place for one year to completely kill off the daylilies underneath. If any daylilies manage to break though a gap in your barrier, spray with Round-Up.
Daylilies And Aphids
Also known as plant lice, aphids are tiny, pear-shaped, soft-bodied insects ranging in color from white to light green and to darker colors. Some aphids have wings and resemble tiny flies. They live in large colonies under leaves and in buds, and they pierce plants with their mouth parts to suck the sap out of daylilies. Black, sooty mold grows on honeydew, and the fungus hampers photosynthesis, leaving unsightly dark spots on plants. If you see a trail of ants around your daylilies, look for colonies of aphids. For small colonies and infestations, spray plants first with water and then with an insecticidal soap or neem oil solution. For severe infestations, you may have to resort to using pesticides. Acephate and malathion are organophosphates, and permethrin is a synthetic compound. They tolerate to a wide range of weather and soil conditions.
- Leave the mulch in place for one year to completely kill off the daylilies underneath.
- They live in large colonies under leaves and in buds, and they pierce plants with their mouth parts to suck the sap out of daylilies.
Related Articles
References
- Helpful Gardener
- University of Vermont Extension: Department of Plant and Soil Science: Dazzling Daylilies
- University of Rhode Island Landscape Horticulture Program: Daylily Culture
- University of California, Integrated Pest Management Online: Pests in Gardens and Landscapes -- Aphids
- University of California Cooperative Extension: Agriculture and Natural Resources Ventura County: Daylily
- University of Missouri Extension: Aphids, Scales and Mites on Home Garden and Landscape Plants
- University of Illinois Extension: Insect Damage: Aphids
- National Pesticide Information Center: Acephate
- National Pesticide Information Center: Malathion
- National Pesticide Information Center: Permethrin
