Crepe myrtles (Lagerstroemia indica) are popular landscape additions known for their extended summer bloom period and attractive exfoliating bark. While these trees are resilient, successfully relocating an established specimen requires careful planning. The most significant factor determining whether a crepe myrtle survives a move is the precise timing of the transplanting process.
Ideal Timing for the Move
The optimal window for transplanting a crepe myrtle is during its dormant season when the plant is not actively growing. This period generally spans from late fall, after the leaves have dropped, through late winter and very early spring. Moving the plant before new leaf buds begin to swell is necessary for its survival.
Late winter, often mid-February to early March in many regions, represents the final opportunity to move the tree before the spring growth cycle begins. This timing allows the tree to immediately focus its resources on establishing new root growth, which begins before the canopy fully leafs out. Even in regions with milder winters, transplanting must occur while the plant is completely leafless and inactive.
Why Dormancy is Critical
Moving a crepe myrtle while dormant significantly reduces the physiological stress it experiences, known as transplant shock. During dormancy, the plant slows its metabolism and ceases energy expenditure on foliage and flowers. Energy reserves are stored primarily in the root system and woody tissues, making them readily available for root regeneration.
When a tree is dug up, a large portion of its existing root system is inevitably severed, severely limiting its ability to absorb water. Moving a tree with an active canopy in summer results in extreme water loss through transpiration, causing immediate and often fatal dehydration. A dormant, leafless tree has virtually no transpiration demand, allowing its limited remaining root system to focus on healing and growing new feeder roots before it needs to support new leaves.
Preparing the Crepe Myrtle for Transplant
When the timing is right, proper preparation of the tree and the new site is necessary to ensure success. Before the move, lightly prune the canopy to compensate for anticipated root loss and reduce the overall water demand once new leaves appear. This light pruning should focus on thinning the canopy rather than severe topping, which can damage the plant’s structure.
To calculate the necessary root ball size, use the trunk diameter (caliper) as a guide. A general rule for deciduous trees is to dig a root ball that is 10 to 12 inches in diameter for every inch of the trunk’s diameter, measured about six inches above the soil line. For example, a three-inch trunk requires a root ball 30 to 36 inches wide. The new planting hole should be dug two to three times wider than the root ball but no deeper, ensuring the tree is planted at or slightly above its original soil line.
Ensuring Post-Transplant Survival
Immediate and consistent aftercare is fundamental to the establishment of the relocated crepe myrtle. Upon placing the root ball in the new hole, water it deeply and thoroughly to settle the soil and eliminate any air pockets. This initial drenching must be followed by a regimen of consistent moisture throughout the first growing season.
Newly transplanted trees require regular, deep irrigation to encourage the development of a robust root system, especially during dry periods. Applying a two to four-inch layer of organic mulch, such as shredded bark or pine straw, helps retain soil moisture and regulate soil temperature. It is important to keep the mulch several inches away from the trunk to prevent moisture buildup that could lead to bark rot. Avoid applying heavy fertilizer until the tree shows clear signs of establishment, as this can encourage shoot growth at the expense of root development.