Growing a crepe myrtle in a container is entirely possible, allowing you to enjoy this sun-loving, flowering tree on patios, decks, or in climates too cold for in-ground planting. Success depends on specific management practices that address the plant’s natural size and the limited environment of a pot. Key steps include selecting the right variety and container, managing its growth, and protecting its roots during winter.
Selecting the Right Variety and Container
The initial choice of plant variety and container size significantly impacts long-term success. Select dwarf or semi-dwarf cultivars, which are bred to maintain a manageable size, typically maturing between three and ten feet tall. Excellent options include members of the Razzle Dazzle series, ‘Pocomoke,’ or the Black Diamond series, all of which have naturally compact growth habits.
The container must be large enough to support the root system for two to three years before requiring an upgrade. A container with a diameter of at least 15 to 20 inches is a good starting point for a young plant. Ensure the pot has ample drainage holes, as crepe myrtles cannot tolerate standing water.
Do not use heavy garden soil, which compacts easily and prevents proper drainage and aeration. Instead, use a high-quality, well-draining potting mix, often containing ingredients like peat moss, perlite, and pine bark fines. This lighter, porous medium promotes healthy root development within the container.
Essential Year-Round Care
Potted crepe myrtles require full, direct sunlight for a minimum of six hours daily to produce abundant flowers. These plants thrive in heat, making a sunny spot on a patio or deck ideal during the active growing season. Insufficient light results in fewer blooms and weaker growth.
Container plants rely completely on the gardener for moisture, so their watering needs are higher than those planted in the ground. During peak summer heat, check the soil daily and water thoroughly until it drains from the bottom. Allow the top two inches of soil to dry slightly between waterings.
The restricted soil volume means nutrients are quickly depleted, making regular feeding necessary. In early spring, apply a balanced, slow-release granular fertilizer, such as a 10-10-10 or a specialized bloom-boosting formula like 10-15-9. Alternatively, apply a liquid fertilizer every four to six weeks during the spring and early summer. Stop fertilization by late summer to signal the plant to harden off new growth for dormancy.
Managing Size Through Pruning and Root Care
Container growing requires both top and root maintenance to keep the plant healthy and proportionate. In late winter or early spring, while the plant is dormant, perform annual top pruning to shape the canopy and encourage vigorous new growth, where summer flowers will form. Focus on removing dead, damaged, or crossing branches, and lightly tip-prune branch ends to encourage bushier growth.
Avoid severe heading cuts, which create thick, unsightly stubs and lead to weak, spindly new branches. This heavy pruning technique, often called “crepe murder,” is unnecessary, especially when a dwarf variety has been selected. The goal is to maintain the plant’s natural, graceful form.
To prevent the plant from becoming root-bound, remove the tree from its container every two to three years for root maintenance. During the dormant season, slide the root ball out and use a sharp knife or saw to slice off approximately one-quarter of the outer root mass, focusing on thick, circling roots. Repot the tree back into the same container using fresh potting mix. This stimulates the growth of new, fine feeder roots that efficiently absorb water and nutrients.
Winter Protection Strategies
The roots of an in-ground crepe myrtle are insulated by the earth, but container roots are exposed to ambient air temperatures, making them vulnerable to freezing. In USDA Hardiness Zones 7 and colder, or when temperatures drop consistently below 20°F, the container must be protected.
The easiest method is to move the dormant plant into a cool, sheltered, unheated location, such as a garage, shed, or basement. The protected area should remain above freezing but cool enough (ideally 35°F to 45°F) to maintain dormancy. While indoors, the plant requires minimal attention.
Reduce watering significantly, providing just enough moisture about once a month to prevent the roots from drying out. Since the plant is dormant, it does not require light. Once the danger of hard frost has passed in the spring, move the container back outside to resume its active growing season.