The daylily, or Hemerocallis, is a popular and resilient perennial, prized for its adaptability and vibrant, trumpet-shaped flowers. Achieving a successful and visually appealing display begins with proper planting. Correctly spacing your daylilies ensures they have the necessary room to develop robust root systems and abundant foliage. This guide clarifies the necessary planting distances, explains the variables that adjust this measurement, and details the maintenance required to preserve optimal spacing.
Standard Spacing Requirements
The general recommendation for planting daylilies is to space them approximately 18 to 36 inches apart, measuring from the center of one plant’s crown to the center of the next. This distance accounts for the plant’s natural tendency to form dense, expanding clumps over several seasons. When planting, dig a hole wider and deeper than the current root system, then set the plant’s crown just one to two inches below the soil surface.
Planting daylilies too closely (less than 18 inches apart) causes foliage to quickly overlap and compete for resources. The resulting lack of air circulation creates a damp, shaded environment, increasing the risk of fungal diseases like rust. Conversely, spacing plants too far apart (beyond 36 inches) creates noticeable gaps that look sparse and take several years to fill in. The standard range provides a balance, ensuring immediate visual appeal while allowing for healthy, vigorous growth.
Factors That Influence Spacing Distance
Spacing should be adjusted based on the mature size of the specific cultivar. Smaller, dwarf varieties, which may only reach a diameter of 12 to 18 inches, can be planted closer together, often requiring only 12 to 18 inches of separation. Larger, more vigorous varieties, including many tetraploids, develop into large clumps and may require the maximum separation of 30 to 36 inches.
The intended aesthetic goal also influences the initial spacing decision. For mass planting, where the objective is dense, quick coverage, planting on the closer end of the 18 to 24-inch range is appropriate. If the goal is specimen planting, where individual plants are meant to stand out and reach their largest potential size, wider spacing of 24 to 30 inches is necessary. Locations with rich soil and full sun promote faster growth and larger clump formation, suggesting a slightly wider initial spacing to accommodate rapid expansion.
Maintaining Optimal Spacing Over Time
Daylilies are fast-growing perennials that spread through their rhizomatous roots, causing the initial spacing to eventually become compromised. Over time, the expanding root systems create a dense, overcrowded clump that competes for resources. This overcrowding is detrimental to the plant’s health, leading to a decline in performance, including reduced bloom count and smaller flower size.
To restore optimal spacing and rejuvenate the plant, division of the clump is necessary, typically every three to five years. Signs that a clump needs division include sparse flowering in the center or a general lack of vigor. The process involves digging up the entire clump and separating it into smaller sections, or “fans.” These fans are then replanted at the original desired distance, resetting the spacing for the next few growing seasons. Division should take place in early spring or after the main bloom period in late summer to allow plants time to establish before frost.