Daylilies (Hemerocallis) are resilient, popular perennials known for their vivid, trumpet-shaped flowers. Although low-maintenance, these vigorous growers eventually require division to ensure continued health. This simple practice prevents overcrowding in the root system, allowing the plant access to necessary nutrients and moisture. Dividing the clumps every few years guarantees prolific summer blooms.
Signs Daylilies Need Splitting
The primary indicator that a daylily clump requires splitting is a noticeable reduction in the number and size of its flowers. This decline in performance typically becomes apparent every three to five years, depending on the cultivar and growing conditions. When the dense, fleshy roots become tightly packed, the plant struggles to absorb adequate resources.
A visual sign of overcrowding is a growth pattern often described as a “doughnut,” where the center of the clump begins to thin out or die back. The foliage may also appear thinner, yellowing, or less vigorous than in previous seasons. These symptoms signal that the congested root mass is hindering the flow of nutrients and water. Dividing the plant at this stage rejuvenates the system and promotes a return to abundant flowering.
Choosing the Right Season for Division
Daylilies can be successfully divided in two windows: early spring or late summer into early fall. Proper timing minimizes transplant shock and maximizes the plant’s ability to establish new roots. The late summer or early fall window is generally the most reliable period for division.
Dividing daylilies after they have finished blooming, typically late August through September, allows the plant to focus energy on root regeneration. This timing works because soil temperatures remain warm enough to stimulate root growth, while cooling air temperatures reduce stress on the foliage. Complete the division at least four to six weeks before the average date of the first hard frost in your region.
The alternative is dividing the clumps in early spring, just as new growth emerges (when leaves are two to four inches tall). A spring division allows the plant an entire growing season to recover before winter. However, this timing may disrupt the plant’s primary growth cycle, sometimes resulting in fewer or smaller flowers during the upcoming summer bloom season.
Step-by-Step Guide to Daylily Division
Preparation and Lifting
The process begins with preparation: thoroughly water the clump the day before to hydrate the plant and soften the soil. Trim the foliage back to six to twelve inches; this reduces the surface area for water loss and makes the root ball easier to manage.
To lift the clump, use a garden fork or spade, inserting the tool ten to twelve inches away from the center to avoid damaging feeder roots. Work the tool around the perimeter to loosen the soil before gently prying the entire root ball from the ground. Once lifted, shake off excess soil or rinse the root mass to make the individual fans more visible.
Separation and Replanting
Separate the large clump into smaller segments. This can often be done by hand or by using two garden forks inserted back-to-back to pull the mass apart. For dense clumps, a sharp knife or shears may be necessary to cut through the intertwined roots. Each separated division, or fan, should retain a healthy root system and at least two to three leaf shoots.
When replanting, prepare the new location by amending the soil with compost. Dig a hole wide enough to comfortably spread out the roots. Place the division so the crown, where the leaves and roots meet, is just at or slightly below the soil surface. Backfill the hole, tamp the soil lightly, and water the newly planted divisions deeply and immediately to settle the soil and eliminate air pockets.