Lilies (Lilium) are among the most revered flowering plants in gardens worldwide. These true lilies, distinct from plants like daylilies (Hemerocallis) or Canna lilies, are grown from scaly bulbs and produce large, often fragrant flowers in many colors and forms. Their stately presence and vibrant summer color make them a popular choice for gardeners. Successfully cultivating these perennial plants depends on understanding their specific needs from planting through dormancy. This guide offers the knowledge required to maintain a healthy and robust lily display.
Getting Started: Planting and Location
Lilies require a well-draining site because the fleshy, scale-covered bulbs are highly susceptible to rotting in overly saturated soil. A sandy loam enriched with organic matter provides the ideal texture, allowing water to pass through quickly while retaining some moisture. If heavy clay soil is present, amending the area with compost or planting in raised beds is recommended to prevent water pooling around the bulb scales.
The best time to plant lily bulbs is in the fall, which allows the roots to establish before winter, though early spring planting is also feasible once the soil is workable. Proper planting depth is crucial for stem-rooting varieties, which produce roots along the buried stem. A general rule is to plant the bulb base about three times its height deep, typically between 6 to 8 inches for standard sizes.
The optimal location adheres to the principle of having “cool roots and a sunny head.” Lilies require at least six hours of direct sunlight daily to produce sturdy stems and abundant blooms, but the soil surrounding the bulb should remain cool. This cooling effect is often achieved by applying a layer of organic mulch or by utilizing low-growing companion plants that shade the soil surface.
Routine Care for Optimal Growth
During the active growing season, consistent moisture is necessary to support the plant’s development, especially as the stems elongate and flower buds begin to swell. Instead of frequent, light sprinklings, lilies benefit from deep, thorough watering during dry periods, aiming to saturate the soil to the depth of the bulb. Maintaining an even moisture level helps prevent bulb stress and ensures the developing flowers reach their full size and color potential.
Feeding should be approached cautiously, as over-fertilization, especially with high-nitrogen formulas, can lead to weak, floppy growth susceptible to disease. Applying a balanced, slow-release fertilizer with a low nitrogen ratio (such as 5-10-10) is appropriate early in the spring as soon as the shoots emerge. A second application can be beneficial after flowering concludes to replenish the bulb’s reserves for the following year.
Taller hybrid varieties, such as Orientals and Trumpets, can reach heights of five to six feet and may require support to prevent wind damage or collapse under the weight of heavy blooms. Installing stakes early in the season, before the plants reach significant height, allows the stem to grow naturally alongside the support structure. Tying the stem loosely with soft material prevents abrasion while securing the plant during summer storms.
Post-Bloom Maintenance and Dormancy Preparation
Once the flowers fade, the immediate task is deadheading, which involves removing the spent blooms and the developing seed pod. This action prevents the plant from expending energy on producing seeds, redirecting those resources back into the underground bulb. Cutting the entire flower stalk prematurely, however, is detrimental to the lily’s long-term health.
The stem and leaves must remain intact after flowering, as the photosynthetic activity in the foliage manufactures the food that strengthens the bulb for the next cycle. Do not cut back the foliage until it has naturally yellowed or browned, signaling that the bulb has absorbed all possible nutrients, usually in the late fall.
In regions experiencing freezing winters, applying a protective layer of organic mulch, such as straw or shredded leaves, helps insulate the bulbs from extreme temperature fluctuations. This insulation maintains a more consistent soil temperature, reducing the risk of the bulbs repeatedly freezing and thawing, which can cause damage.
Managing Pests and Common Diseases
The most significant pest threat to lilies is the scarlet red lily beetle (Lilioceris lilii), easily identifiable by its bright red shell and black head and legs. Both the adult beetles and their larvae, which hide under a protective layer of their own excrement, consume foliage, buds, and flowers rapidly, often defoliating plants within days. Manual removal is the most effective control measure, involving regularly inspecting the plants and dropping the beetles into soapy water before they can lay eggs.
Aphids are also common and can cluster on new growth and buds, where they suck plant sap and potentially transmit viruses. A strong jet of water can dislodge these soft-bodied insects, or insecticidal soap can be applied if the infestation is severe. Prompt action against aphids is advisable to minimize the risk of virus spread, which often requires the removal of the entire infected plant to protect others.
Fungal issues, particularly Botrytis blight (Botrytis elliptica), manifest as brown spots on the leaves and spread quickly in cool, wet conditions. Prevention centers on ensuring good air circulation around the plants by spacing them appropriately and avoiding overhead watering late in the day. Removing and destroying any infected leaves immediately upon detection helps limit the pathogen’s ability to sporulate and spread to healthy tissue.