Crabapple trees (Malus species) are popular ornamental fixtures known for their spring blossoms and persistent fruit. Homeowners often seek complementary plantings that can thrive beneath the canopy. Selecting the right companion plants is challenging due to the specific environmental conditions created by the mature tree, which must be addressed for successful underplanting.
Analyzing the Growing Environment
Understanding the unique conditions beneath a crabapple is foundational to successful underplanting. Once fully leafed out, the tree creates dappled to moderate shade that shifts throughout the day. Suitable underplants must tolerate these reduced light levels compared to an open garden bed.
A significant challenge is the crabapple’s dense, fibrous root system, which is shallow and highly competitive. These roots aggressively monopolize available water and nutrients in the upper soil layers. Therefore, planting requires care to avoid damaging these roots and selecting species that can survive with limited resources.
Crabapples thrive in well-drained loamy soils with a slightly acidic pH, typically ranging from 6.0 to 6.5. Companion plants must tolerate these mildly acidic conditions. The combination of shade, intense root competition, and specific soil chemistry defines the limited palette of plants that can flourish here.
Recommended Low-Growing Groundcovers
The best options for permanent underplanting are low-growing groundcovers that withstand dry shade and root competition.
Shade-Tolerant Foliage
Small-to-medium Hosta varieties, such as ‘Blue Mouse Ears’ or ‘Halcyon’, are excellent choices. They are shade-tolerant and have shallow root systems that minimize competition with the tree. Their substantial foliage provides texture and color variations throughout the growing season.
Ferns are a highly compatible group, including the Japanese Painted Fern (Athyrium niponicum) or the Autumn Fern (Dryopteris erythrosora). These ferns have fine, shallow roots and are accustomed to filtered light and drier soil conditions found in woodland environments. They offer a delicate contrast to the canopy without requiring extensive soil preparation.
Creeping Groundcovers
Vinca minor (periwinkle) is a classic choice due to its vigorous, mat-forming habit. This evergreen groundcover establishes quickly and is highly tolerant of dry shade once rooted. It suppresses weeds effectively and features small blue or white flowers in the spring.
Ajuga reptans (Bugleweed) offers a low-profile, dense carpet that thrives in low light and tolerates drier soil. Its dark foliage and short flower spikes add subtle color and texture. Both Vinca and Ajuga spread via stolons, colonizing the area using surface runners rather than deep, aggressive roots.
For areas receiving slightly more light or having better drainage, shade-tolerant Sedums (Stonecrop) can be successful. These succulents store water in their leaves, giving them an advantage against the tree roots competing for moisture. Selecting compact, creeping varieties ensures they remain low and do not require deep soil.
Adding Seasonal Color with Bulbs and Annuals
Temporary plantings allow for bursts of color that capitalize on the crabapple’s annual cycle, complementing permanent groundcovers. Spring-flowering bulbs are effective because they complete their bloom period and store energy before the tree’s canopy fully develops, accessing maximum sunlight before the shade becomes restrictive.
Spring Bulbs
Early bloomers emerge and flower while the tree is still dormant.
- Snowdrops (Galanthus)
- Siberian Squill (Scilla siberica)
- Crocus
- Small varieties of Daffodils (Narcissus)
These bulbs rely on the moist, cool soil of early spring and go dormant as the soil dries out in summer, minimizing competition during the peak growing season.
Summer Annuals
For summer color, annuals bypass the issue of long-term root competition. Shade-loving annuals, such as Wax Begonias (Begonia semperflorens) or Impatiens (Impatiens walleriana), can be planted directly into a shallow layer of amended soil. Since they are temporary, their root systems remain small, requiring minimal soil disturbance during installation.
Annuals require consistent surface watering during establishment, but their shallow root structure supports quick, vibrant displays. Choosing annuals allows the gardener to refresh the color palette yearly without impacting the established root zone of the mature tree.
Safe Installation and Maintenance Practices
Successful underplanting relies heavily on proper installation. The most important practice is root avoidance; gardeners should never dig deep, uniform holes near the trunk. Instead, focus on finding natural pockets of soil between the large, structural tree roots where small plants can be inserted.
When planting bulbs or groundcovers, use a hand trowel to gently move soil aside, minimizing disturbance to the tree’s root system. The disturbed area should only be large enough to accommodate the plant’s root ball, which should be placed shallowly, perhaps slightly above the surrounding grade.
To give new plants an advantage, use a high-quality, lightweight soil amendment or compost mixed with the existing topsoil. This provides a temporary boost of nutrients and better water retention. Do not pile this material directly against the crabapple trunk, as this can lead to moisture issues and rot.
New plantings require attentive establishment watering, as they initially struggle against the tree’s superior ability to absorb moisture. Once established, the plants tolerate drier conditions, though occasional deep watering during extended dry periods benefits both the tree and the underplants. Maintenance should include light, low-nitrogen fertilization.