Transplanting bulbs involves moving established underground storage organs (including true bulbs, corms, tubers, and rhizomes) from one location to another. This practice is often necessary to maintain plant health or accommodate garden design changes. Timing is the most influential factor determining success, as moving a bulb at the wrong moment disrupts its energy cycle and prevents future flowering. Understanding the plant’s dormancy phase is key to ensuring it survives and thrives in its new location.
Signs That Bulbs Need Relocation
Gardeners usually transplant bulbs when the colony shows signs of decline or overcrowding. A reduction in the size or quantity of flowers produced indicates the bulbs are struggling. This decreased vigor often occurs because the mother bulb has multiplied, creating numerous smaller offset bulbs that compete intensely for light, water, and nutrients.
The visual density of the foliage and stems also signals a need for division. When clumps become too tight, air circulation decreases, making the plants susceptible to fungal diseases and pests. Bulbs typically benefit from being lifted and divided every three to five years before these issues become severe. Relocation may also be required to move them from a newly shaded area or integrate them into a new garden design.
Optimal Timing Based on Bulb Type
The best time to move a bulb is when it is fully dormant, meaning the plant has completed its annual growth cycle and is resting.
For spring-flowering bulbs like tulips, daffodils, and hyacinths, this window opens in late spring or early summer, after blooming has finished. It is necessary to wait until the foliage has naturally yellowed and died back completely. The green leaves actively photosynthesize to replenish the bulb’s energy stores for the following year’s bloom.
If moving spring bulbs is not possible in late spring, the alternative time is early fall, several weeks before the ground freezes. The bulbs are completely dormant then and can be replanted, allowing roots to establish before winter. Transplanting while foliage is still green or during active growth interrupts energy storage, resulting in a lack of flowers the next season.
Summer- and fall-flowering bulbs, including dahlias, gladiolus, and cannas, follow a different schedule. Hardy summer bulbs, such as lilies, are best transplanted in early spring before new shoots emerge or in the fall once the foliage has died down. Tender bulbs, which are not winter-hardy, must be lifted for storage in cold climates. They should be dug up in late fall after the first light frost causes the foliage to collapse, but before a hard freeze damages the underground structure.
Essential Steps for Successful Transplanting
Extraction and Selection
Once the correct timing is determined, extraction must be handled with care to prevent damage to the bulb structure. Use a garden fork, rather than a shovel, to gently loosen the soil, inserting the tool six inches or more away from the visible stem to avoid spearing the bulb. Lift the entire clump from beneath and shake off excess dirt to expose the main bulb and any smaller offset bulbs.
The new planting location must be prepared before extraction to minimize the time bulbs spend out of the soil. Bulbs require well-draining soil, so amend the new site with compost or organic matter, especially in heavy clay soils. Discard any bulbs that feel soft, appear diseased, or show signs of pest damage, keeping only the firm, healthy specimens for replanting.
Replanting Depth and Spacing
The general rule for replanting is to set the bulb at a depth that is two to three times its height, typically four to six inches deep for most common bulbs. Ensure the pointed side faces upward, as this is where the new shoot will emerge. Space the bulbs apart at least twice their width to prevent immediate re-overcrowding and allow for future multiplication. After covering the bulbs with soil and gently firming the area, a thorough watering is necessary to settle the soil and initiate root development.