Asiatic lilies (Lilium asiaticum) are vibrant perennial plants prized for their upward-facing flowers and wide range of colors. Propagating them is a reliable method to increase stock and rejuvenate older, overcrowded clumps. While lily bulbs naturally multiply underground, gardeners can accelerate this process using two primary asexual reproduction techniques: bulb division and scaling.
Timing and Preparation for Propagation
The ideal time to propagate Asiatic lilies is in late summer or early fall, immediately following the blooming period and as the foliage begins to yellow but before the plant enters full dormancy. This timing allows the newly separated bulbs or scales maximum time to establish roots before winter arrives. Propagating during this phase ensures the plant has stored sufficient energy for regeneration while its active growth cycle has slowed.
Before beginning, gather necessary tools. A garden fork or spade is necessary for gently lifting the entire bulb clump from the soil. You will also need a sharp, sterile knife or razor blade, which is important for the scaling process to make clean cuts and prevent pathogen transmission.
Reduce watering for a few days before digging the clump, which makes the soil lighter and easier to work with. Once the clump is carefully lifted, shake off the excess soil to expose the bulb cluster and any offsets. Keep fungicide powder or a dilute bleach solution ready to treat any exposed cuts or wounds on the bulbs immediately.
Step-by-Step Guide to Bulb Division
Bulb division is the simplest and fastest method for propagating Asiatic lilies, yielding immediate, mature new plants. It relies on separating the natural offsets, or daughter bulbs, that have formed around the original mother bulb over several seasons. The process begins by gently lifting the entire clump using a garden fork, aiming to get under the main root mass to minimize damage.
Once lifted, brush away the excess soil to reveal the entire bulb structure. You will notice smaller bulbs, known as offsets, attached to the main parent bulb. These offsets are ready to be separated.
The offsets can often be gently pulled apart by hand. If the bulbs are tightly clustered, a sterile knife may be necessary to slice through the connecting tissue. Ensure each section retains a portion of the basal plate where the roots emerge. Each separated division must have a healthy set of roots and a growing point, often called a “nose.”
Any cut surfaces on the bulb divisions should be dusted with fungicide powder to prevent fungal rot. These newly separated bulbs are ready for immediate replanting in their new locations. Immediate replanting minimizes the risk of the bulbs drying out and ensures quicker recovery and establishment.
The Process of Bulb Scaling
Scaling is a method of propagation that allows a single bulb to produce a large number of new plants, making it ideal for multiplying rare varieties. This technique exploits the bulb’s structure, which consists of fleshy leaves called scales capable of generating new tissue. You must first select a firm, healthy bulb for scaling, as damaged or soft tissue will likely fail to produce viable offspring.
Once the bulb is harvested, carefully remove four to eight of the outermost scales by gently twisting or snapping them off at their base. The critical detail here is ensuring that a small, intact piece of the basal plate, the tissue from which the roots grow, remains attached to the base of each scale. If the scale breaks off above this plate, it will not be able to form a new bulb.
To discourage fungal contamination, sanitize the separated scales by dipping them in a dilute solution of fungicide or a 10% bleach solution, then allowed to air-dry briefly. Next, place the scales into a clean plastic bag filled with a sterile, moist growing medium, such as a mix of peat moss and vermiculite. The medium should be damp, like a wrung-out sponge, to provide moisture without promoting rot.
Seal the bag and place it in a dark, warm environment, ideally maintaining a temperature around 70°F. Within six to eight weeks, tiny new bulblets, known as bulbils, will begin to form at the base of the scales. The scales act as a nutrient source for these developing bulbils during this incubation period.
Care for Newly Propagated Lilies
The care required depends on whether the plants resulted from division or scaling. Divisions are mature plants and should be replanted immediately at the same depth they were previously growing, typically six to eight inches deep. Ensure the soil is well-draining, as the divisions are prone to rot if they sit in waterlogged conditions.
The tiny bulbils resulting from scaling require vernalization, or cold treatment, to break dormancy. After the incubation period, the sealed bag of scales and bulbils should be moved to cold storage, such as a refrigerator, for six to twelve weeks at a temperature just above freezing. This chilling period mimics winter and signals the bulbil to begin top growth.
After the cold period, the bulbils can be gently separated from the scales and planted in shallow trays or pots filled with a sterile potting mix, covering them with about an inch of soil. Keep these young plants in a protected, bright location with partial sun and consistent moisture. They should grow for one to two full seasons before being transplanted to their final garden spot.