Daylilies, members of the Hemerocallis genus, provide flowers that complete their bloom life in one day. When one flower fades, another bud opens, creating continuous flowers during the summer. Mature daylilies produce 200 to 400 flowers in a growing season. With this expectation in mind, you might be surprised if your daylilies are not blooming. The planting site or health of your daylily might be the cause.
Plants under stress show a decline in flowering. Daylilies are somewhat tolerant to drought, but they still need plenty of water during flowering. The University of Minnesota Extension suggests supplying one inch of water per week. Consider watering your daylilies more often if the soil is sandy. Too much light or too much shade also reduces flowering. Daylilies provide abundant blooms with at least six hours of full sun. Too much direct sun, however, may burn dark-colored flowers, which soak up the heat. Alabama Cooperative Extension recommends protecting daylilies with dark flowers from the scorching afternoon sun.
Crowded roots reduce the number and quality of flowers on your daylily plants. Purdue University recommends dividing daylilies every five to seven years to give roots more room. Ensure that each divided clump has roots and two to three stems. Divide plants when they are not flowering during late fall, late winter or early spring. The University of Minnesota Extension states that dividing your daylilies in the spring could lead to reduced flowering that summer.
Improper planting of daylilies reduces flowering. Before planting in the ground, be sure to cut off the top part of the leaves. This prevents water loss through transpiration and reduces plant stress. When planting, it is important to place the crown at or above the surface of the soil. Daylilies that are planted too deep do not produce healthy vegetation or flowers.
Day lily rust, identified in the United States in 2000, is a fungus (Puccinia hemerocallidis) that attacks daylily plants. Symptoms include yellow or brown streaking on leaves and yellow spots under the leaves. Severe cases of daylily rust reduce flowering. Treatment options include weekly applications of fungicide and removal of infected plant debris. If daylily rust is a problem in your growing area, consider planting resistant varieties.