Daylilies (Hemerocallis) are hardy perennial plants that can be successfully planted in the fall. Although they are not true lilies, their tolerance for a wide range of growing conditions makes them a popular choice for gardeners. Planting in autumn is an effective strategy for ensuring robust growth and strong blooms the following season, as cooler temperatures and increased rainfall help the plants establish themselves.
Identifying the Ideal Fall Planting Window
Successful fall planting requires timing the process to allow for significant root development before the ground freezes solid. The optimal window is generally six to eight weeks before the region’s average date for the first hard frost. This period provides a balance of cooling air temperatures and still-warm soil temperatures.
Root growth is driven by soil warmth. New feeder roots actively form when the soil temperature is consistently above 50°F (10°C), ideally between 55°F to 65°F (13°C to 18°C). Planting too late means the soil will be too cold for roots to anchor and store energy for winter survival.
This establishment time allows the daylily to develop an extensive root system. A well-established root mass draws on moisture and nutrients, giving the plant a considerable advantage when new growth begins in the spring.
Step-by-Step Guide to Planting Daylilies
The planting process begins with site preparation in a location that receives at least six hours of direct sunlight daily. While daylilies are adaptable, amending the soil with organic matter like compost or aged manure improves drainage and nutrient retention. Loosening the soil to a depth of 12 inches allows the fleshy roots to spread.
Dig a hole about twice as wide as the root mass. If planting a bare-root daylily, create a small soil mound in the center of the hole and spread the roots over it. This technique ensures the roots are angled downward, promoting deep growth.
Crown Placement
Positioning the crown—the point where the roots meet the leaves—is crucial. The crown should be set at or slightly below the soil surface, no more than one inch deep. Planting too deeply can lead to rot, while planting too shallowly can cause the roots to dry out. Gently backfill the hole with amended soil, firming it lightly to eliminate air pockets.
Ensuring Winter Survival
The first step after planting is to water the daylily deeply and thoroughly. This initial watering settles the soil around the roots and removes air pockets that can dry out the roots.
Consistent moisture is necessary until the ground freezes for the winter. Even after the foliage dies back, the roots are vulnerable to desiccation caused by cold, windy conditions. If the fall is dry, provide supplemental deep watering about once a week.
Applying a thick layer of mulch is an effective measure for winter protection. A layer of four to six inches over the planting regulates soil temperature and prevents frost heave. Frost heave occurs when repeated freezing and thawing cycles push the root crown out of the soil.