Daylilies (Hemerocallis) are garden perennials known for their adaptability and low maintenance. While these plants can tolerate poor soil conditions, they are heavy feeders that respond well to a managed nutritional program. Providing the right nutrients at the correct time enhances their vigor, supports robust foliage, and maximizes summer bloom performance. Successful daylily cultivation relies on understanding the plant’s growth cycle to time fertilizer applications for maximum benefit.
The Critical Spring Application
The most impactful time for the first application of fertilizer is early in the spring season, just as the daylily begins to emerge from dormancy. Gardeners should apply this initial feeding when the new green shoots are visibly poking through the soil, typically reaching a height of about six to eight inches. This timing ensures the nutrients are immediately available to support the plant’s rapid emergence from winter rest and its foundational growth. This spring feeding is designed to stimulate the development of a strong, healthy root system. Promoting deep root growth early sets up the plant’s energy reserves for the summer flowering period. A robust root structure enables the daylily to efficiently absorb water and nutrients, which are prerequisites for producing numerous flower scapes later on.
Mid-Season Boost and Post-Bloom Timing
A second fertilization provides a necessary energy boost after the plant has expended initial reserves on foliage and the first wave of flower production. This follow-up application is recommended approximately six to eight weeks after the initial spring feeding, or immediately following the conclusion of the main flush of blooms. The goal is to replenish the soil’s available nutrients to sustain the plant through the remainder of the growing season. This mid-season timing is beneficial for reblooming varieties, such as Hemerocallis ‘Stella de Oro’, as it encourages the formation of new scapes and a second cycle of flowers. The nutrients applied now shift the plant’s focus from seed production to continued vegetative and reproductive growth. Supporting the plant after its primary effort ensures the foliage remains healthy and green, which continues to photosynthesize and store energy for the following year.
Selecting the Right Fertilizer Type
Daylilies generally thrive on a balanced fertilizer, or one that is slightly higher in phosphorus and potassium. A common recommendation is a balanced N-P-K ratio like 10-10-10, where all three primary nutrients—Nitrogen, Phosphorus, and Potassium—are present in equal measure. Alternatively, a formula such as 5-10-10 or 5-10-5, which features a lower nitrogen content, is often preferred to encourage more flowers instead of excessive leafy growth. Nitrogen (N) supports green foliage, Phosphorus (P) is linked to root and flower development, and Potassium (K) helps with overall plant health and resilience. Slow-release granular fertilizers provide a steady supply of nutrients over several months, preventing rapid growth spurts. Liquid fertilizers can be used for a quick boost to deliver nutrients directly to the roots when a rapid response is desired.
Application Techniques and Avoiding Over-Fertilization
The application of granular fertilizer should focus on the area around the perimeter of the daylily clump, corresponding to the plant’s drip line. Spread the granules evenly over the soil surface, taking care to avoid direct contact with the crown of the plant where the leaves emerge. Fertilizer placed directly on the crown can lead to chemical burn, damaging the tender new tissues and potentially causing the plant to rot. After applying the dry granules, the area must be thoroughly watered to dissolve the fertilizer and move the nutrients down into the root zone. Watering immediately prevents the risk of leaf or root burn and ensures the plant can begin absorbing the nutrients. Cease all fertilization by mid-August, especially in regions with cold winters, to allow the plant to prepare for dormancy. Fertilizing too late in the season can promote tender new growth that is susceptible to damage from the first frost.