The Crepe Myrtle (Lagerstroemia) is a beloved landscape tree, especially across warmer regions in USDA Hardiness Zones 7 through 10, valued for its extended summer bloom period and attractive, often exfoliating bark. Successfully integrating this heat-tolerant plant requires selecting compatible partners that enhance its aesthetic qualities and support its health. Companion planting involves choosing species that share similar cultural requirements, creating a harmonious visual display while reducing maintenance. This strategy ensures that both the tree and its companions thrive without competing for limited resources.
Establishing Environmental Criteria
Successful companion planting requires understanding the Crepe Myrtle’s specific needs. The tree requires a minimum of six hours of direct, unfiltered sunlight daily to support vigorous growth and maximum summer flowering. Companions must also thrive in full sun to prevent them from becoming leggy or failing to bloom. Lagerstroemia demands well-draining soil, preferring a slightly acidic to neutral pH range of 5.5 to 7.0.
Any suitable companion must tolerate these soil conditions and be drought-tolerant once established. While a newly planted Crepe Myrtle needs regular watering, mature trees are exceptionally resilient to dry spells. Matching the water needs of companions to the mature tree prevents the over-irrigation that can lead to fungal issues, such as powdery mildew. Choosing plants with similar requirements minimizes competition for moisture and nutrients.
Low-Growing and Groundcover Selections
The area immediately surrounding the Crepe Myrtle trunk benefits greatly from a living groundcover layer that suppresses weeds and conserves soil moisture. Low-growing plants should remain under 12 inches in height to avoid visually competing with the tree’s lower structure and multi-stemmed form. These selections offer an opportunity to highlight the Crepe Myrtle’s cinnamon-colored or grey bark, which often peels to reveal a mottled texture underneath. Planting low-profile companions also reduces the need for mulch, which should be kept a few inches away from the trunk to prevent moisture retention against the bark.
Stonecrop (Sedum) varieties, particularly creeping types, are excellent choices due to their succulence and minimal water needs. Their dense foliage provides year-round texture and small flowers that contrast with the tree’s large panicles. Liriope muscari, or Border Grass, offers fine, grass-like foliage that creates a textural contrast and subtle purple or white flower spikes in late summer. Low-growing Dianthus also works well, providing a splash of color with its fringed petals while tolerating dry, sunny conditions.
Mid-Layer Perennials and Shrubs
A middle layer of plants, generally between one and three feet tall, provides structure and seasonal interest slightly outside the immediate root zone of the Crepe Myrtle. Selecting perennials with contrasting foliage colors draws attention to the tree’s abundant summer blooms. For example, plants with silvery or blue-green leaves provide a cool backdrop that makes the Crepe Myrtle’s pink, red, or purple flowers appear more vibrant.
Ornamental Grasses are superb mid-layer options, with dwarf varieties of Fountain Grass (Pennisetum) adding fine texture and movement. Their arching form and late-season plumes complement the tree’s upright stature and offer winter interest. Russian Sage (Perovskia atriplicifolia) is a reliable choice, featuring silvery foliage and spikes of lavender-blue flowers that thrive in intense heat and sun. The blue tones of Russian Sage create a striking complementary color scheme against the Crepe Myrtle’s warm-colored flowers.
Purple Coneflower (Echinacea purpurea) provides sturdy, daisy-like blooms from mid-summer into fall, attracting pollinators while tolerating dry, sunny conditions. Compact Spirea varieties, which are woody shrubs, also work well, offering a different form of foliage and a spring bloom that precedes the Crepe Myrtle’s summer display.
Planting Strategy and Poor Neighbors
Implementing a successful planting strategy requires careful attention to spacing and resource management to ensure the Crepe Myrtle remains the dominant, healthy specimen. When placing companion plants, avoid digging or planting anything within a 12 to 15-inch radius of the Crepe Myrtle’s trunk to prevent damage to its shallow surface roots. Instead, begin the companion planting ring further out, allowing the tree’s root system to remain undisturbed. Applying a layer of organic mulch outside of the planting area helps to regulate soil temperature and conserve moisture, but it must not be piled against the tree’s base, which can promote fungal growth and bark rot.
Certain plants are incompatible and should be avoided due to conflicting resource needs or growth habits. Plants requiring consistent moisture or shade, such as Hostas, Impatiens, or certain Hydrangea species, should not be paired with Lagerstroemia in a full-sun setting. Overwatering these companions would stress the tree and invite disease. Heavy feeders requiring frequent, nitrogen-rich fertilization are also poor neighbors, as excessive nitrogen promotes leafy growth at the expense of flower production. Avoiding aggressive, spreading plants or deep-rooted competitors ensures the Crepe Myrtle maintains access to the resources it needs.