Daylilies (Hemerocallis) are perennial plants with a distinct growth cycle that influences their nutrient needs. In early spring, they emerge from dormancy, producing new foliage and preparing for flowering. During summer, they bloom vigorously, and by fall, they begin storing energy in their roots for winter survival. Fertilizing at the right time aligns with these phases to support optimal growth and flowering.
As daylilies break dormancy in early spring, they require a balanced fertilizer (e.g., 10-10-10) to fuel leaf and stem development. Apply fertilizer when soil temperatures reach around 50°F (10°C), typically when new growth is 2-4 inches tall. This provides essential nitrogen (N) for foliage, phosphorus (P) for root health, and potassium (K) for overall vigor. Avoid over-fertilizing, as excessive nitrogen can lead to lush foliage at the expense of blooms.
About 4-6 weeks before the expected bloom period (late spring to early summer), a second application of fertilizer can enhance flower quality. Use a formula with higher phosphorus content (e.g., 5-10-5) to promote bud formation and vibrant blooms. Ensure the fertilizer is watered in thoroughly to prevent root burn and maximize nutrient uptake.
After flowering, daylilies shift focus to root and rhizome development. A light application of balanced fertilizer in mid-to-late summer helps replenish energy stores. Avoid high-nitrogen fertilizers at this stage, as they may stimulate late-season growth vulnerable to frost damage. Instead, opt for a slow-release formula to sustain the plant until dormancy.
In early fall, a final fertilizer application with higher potassium (e.g., 0-0-50) can strengthen roots and improve winter hardiness. However, avoid fertilizing too late in the season, as new growth may not harden off before frost. In colder climates, skip fall fertilization and rely on spring and summer feedings.
Daylilies thrive in well-draining, slightly acidic to neutral soil (pH 6.0–7.0). Conduct a soil test to tailor fertilizer choices to nutrient deficiencies. In sandy soils, frequent light applications are better, while clay soils benefit from fewer, heavier doses. Always water deeply after fertilizing to prevent salt buildup and ensure nutrient absorption.
Compost, aged manure, or organic fertilizers (e.g., fish emulsion) can replace synthetic options. Apply compost in early spring and mid-summer to improve soil structure and provide slow-release nutrients. Organic matter also enhances microbial activity, fostering long-term plant health.
Yellowing leaves may indicate nitrogen deficiency, while poor flowering suggests low phosphorus. Over-fertilization can cause leaf burn, weak stems, or reduced blooms. Adjust fertilization practices based on plant response and soil test results.
