Daylilies (Hemerocallis) are a staple in many gardens due to their hardiness and vibrant, trumpet-shaped flowers. As resilient perennials, they require minimal care once established. However, their vigorous growth habit means they eventually become overcrowded. Dividing the clump is a necessary gardening practice that rejuvenates the plant, ensures robust flowering, and provides an easy way to propagate and expand your garden display.
Signs Your Daylilies Need Splitting
Daylilies show clear visual cues when the dense root mass begins to hinder performance, typically occurring every three to five years. The most noticeable sign is a significant reduction in the number of flowers produced, often accompanied by smaller bloom sizes. This occurs because tightly packed roots cannot efficiently absorb and transport sufficient nutrients and water to support extensive flowering.
The foliage may also appear less vigorous, becoming thin or yellowed, indicating a struggle for resources. Additionally, a distinct “donut hole” or dead patch may develop in the center of the clump where the oldest part of the plant has died out from lack of space and light. Addressing these symptoms through division restores access to soil resources for the remaining, healthier sections.
Optimal Seasons for Division
The most successful times for dividing daylilies are during periods of low growth activity, which minimizes stress on the root system. Gardeners typically choose between early spring and late summer or early fall.
Dividing in early spring is advantageous because the plant is just emerging from dormancy, with new growth only a few inches tall. This timing allows the newly separated divisions a full growing season to establish a strong root system before the heat of summer. The entire clump is also easier to manage before it has fully leafed out.
The second window is late summer, immediately after the main flowering period, or early fall. This timing is suitable in warmer climates where spring heat arrives quickly. When dividing in the fall, complete the task at least four to six weeks before the first hard frost is expected. This window gives the divisions enough time to develop anchor roots, preventing the plant from being pushed out of the ground by freezing and thawing soil cycles during winter.
The Process of Splitting and Replanting
Lifting the Clump
Before digging, trim the foliage back to 8 to 12 inches to reduce moisture loss and make the clump easier to handle. Use a sharp spade or garden fork to loosen the soil in a circle 6 to 12 inches away from the plant’s crown. Carefully leverage the entire root ball out of the ground, aiming to keep as much of the root system intact as possible.
Separating Divisions
Once lifted, gently shake or rinse away excess soil to expose the roots and the individual fan-shaped growth points. Separation can often be achieved by hand, pulling the fans apart where they naturally separate. For very dense clumps, a sharp knife, a saw, or two garden forks inserted back-to-back can be used to cut the mass into smaller pieces. Each division should contain at least two to three fans of leaves and a robust section of the root system to ensure successful re-establishment.
Replanting
Prepare the new planting site by digging a hole wide enough to accommodate the spread of the roots. The crown (the white core where the leaves meet the roots) should be set at or just slightly below the soil surface, approximately one inch deep. Spread the roots out in the planting hole and backfill with soil, gently firming it to remove any air pockets.
Establishing Divided Daylilies
Immediate and consistent watering is the most important step for establishing newly divided daylilies. After replanting, saturate the soil thoroughly to settle the soil around the roots and eliminate any air pockets. Keep the soil consistently moist for the first few weeks as the roots begin to grow into the new location.
If division was performed during warmer weather, temporary afternoon shade can help reduce transplant shock while new roots are forming. Apply mulch around the base of the plant, keeping it away from the crown, to retain soil moisture and maintain a cooler soil temperature. New divisions generally do not require immediate fertilization; wait until new green growth is visible before applying a balanced, slow-release fertilizer to avoid burning the roots.