Daylilies (Hemerocallis spp.) are prolific perennial bloomers that provide masses of flowers ranging from diminutive blossoms to gigantic flowers measuring up to 9 inches across. Although daylilies are sturdy plants that bloom without fertilizer, regular feedings provide the nutrition the plants need to produce the biggest, most colorful flowers.
Get your daylilies off to a good start by improving the soil with organic materials and fertilizer before planting. Cultivate the soil thoroughly. Work in 3 to 4 inches of organic material such as well-rotted animal waste or compost along with a fertilizer with a ratio similar or equal to 3-to-1-to-2. Apply the fertilizer at the rate of about 3/4 to 1 1/2 lb. for each 100 square feet of planting area. Mix the organic material and fertilizer thoroughly into the top of the soil.
After planting, established daylilies benefit from regular feeding every year in autumn, early spring and mid-summer. Use the same granular fertilizer, with a ratio of approximately 3-to-1-to-2, that was applied at planting time. Apply the fertilizer at the rate of 3/4 to 1 1/2 lb. for every 100 square feet of planting area.
Sprinkle the granular fertilizer evenly on the soil around the daylily plants, but keep the fertilizer away from the foliage. Spray the foliage with water immediately if fertilizer lands on the leaves, as the fertilizer can damage the foliage. Water deeply immediately after fertilizing, as fertilizer applied to dry soil can burn the roots.
Although the fertilizer suggestions are good general rules for keeping your daylilies healthy, a soil test is the best way to determine your soil quality. A soil test determines the pH level in your soil, as well as levels of phosphorus, potassium, calcium and magnesium in your soil. Your local cooperative extension office will direct you how to proceed, and after testing, can help you understand the best ways to amend the soil to correct any problems.