Two popular landscape plants for temperate-zone gardens include the crabapple (Malus spp.) and the plantain lily (Hosta spp.). Crabapple trees need full sun to flower well, while hostas look their best with protection from sunlight and soft, moist soil. In theory, planting hostas under crabapple trees will work, but issues of tree roots, low branches, access and falling debris can pose dilemmas.
Crabapple trees need at least six hours of direct sunlight daily for best tree shape and form as well as for prolific flowering and potential fruit crops. Conversely, hostas in general must be kept out of intense summer sunlight to prevent leaf browning, bleaching to white or scraggly looking plants with few leaves. As long as the crabapple tree is large enough to cast shade, protecting hosta foliage from the most intense sunlight from 11 a.m. to 5 p.m. during the growing season, hostas can be planted.
Both crabapples and hostas are hardy in regions with cold winters, in general in USDA Hardiness Zones 3 through 8. Certain select varieties of each may prove better suited to local growing conditions and climates.
Both crabapples and hostas will prosper in a fertile, organic-rich soil that is moist during the growing season. However, tree roots remain in the top 12 inches of topsoil in a broad matrix that will be in direct competition with any plants, including hostas planted under the tree canopy. Irrigation to planting beds with both plants in proximity, along with organic mulch, can allow for good growth of both crabapple and hostas.
If soils are compact or dry, both plants will drop foliage or have yellowed, less attractive foliage. In competition, an established tree will outpace a hosta plant for uptake of soil water and nutrients.
While the crabapple tree is physically seen year-round, the hosta plant goes dormant in fall and winter. When the tree flowers in spring, the hostas are likely not yet fully emerging their rolled leaves. Thus, as crabapples are admired close up, dormant hosta plants may be trampled. Moreover, some tree species retain their lowermost branches, making it difficult to see or maintain hosta plants under the canopy. If branches on the tree are to be pruned, access around the tree is needed so that understory hosta plants are not trampled and damaged.
Crabapple trees drop debris, including petals, twigs, foliage and small fruits. Depending on the season, this unsightly fallen debris can cover the hostas, and in some cases the twigs or fruits can puncture hosta foliage. In general, the debris is not detrimental to these two plants' compatibility, but a gardener may find seasonal litter troublesome, increasing the need for access around the plants for maintenance.