Layered garden design: canopy to ground

Layered garden design -- also called vertical layering or forest layering -- is the practice of designing a planting that includes multiple vertical levels of plant life, from tall canopy trees down to ground-layer plants. Per Cornell Cooperative Extension, this mirrors the structure of natural.

Layered garden design — also called vertical layering or forest layering — is the practice of designing a planting that includes multiple vertical levels of plant life, from tall canopy trees down to ground-layer plants. Per Cornell Cooperative Extension, this mirrors the structure of natural forest and woodland edges, which are among the most productive and biodiverse ecosystems in temperate North America.

The principle is both ecological (wildlife habitat requires all vertical layers) and practical (more layers = more plants per square foot = more visual interest per unit area).

The five layers

Per USDA Natural Resources Conservation Service and Xerces Society woodland garden guidance:

Layer 1: Canopy trees (30—80+ ft)

The dominant upper layer. In residential landscapes, this is typically limited to one or a few existing trees, or one new tree added as an investment in future structure.

Ecologically valuable native canopy trees (eastern US):

• Quercus (oak) — per Tallamy's research via Xerces Society, oaks support more caterpillar species than any other North American tree genus
• Carya (hickory) — high wildlife value; hard mast for mammals; per Xerces, supports 200+ caterpillar species
• Ulmus (elm) — disease-resistant varieties available; important host tree
• Betula (birch) — canopy for smaller spaces; important for caterpillars

Layer 2: Understory trees (15—30 ft)

Smaller trees growing beneath the canopy layer. This is where most of the ornamental flowering trees sit.

• Cornus florida (flowering dogwood) — native; high wildlife value; per Xerces, fruit eaten by 30+ bird species
• Amelanchier (serviceberry) — native; early spring bloom; fruit
• Cercis canadensis (redbud) — native; early spring bloom; important pollen source
• Ilex opaca (American holly) — native evergreen; important winter berry

Layer 3: Shrub layer (3—15 ft)

The most designable layer for most homeowners — what most planting is focused on. Per NC State Extension, the shrub layer provides:

• Nesting sites for birds
• Fruit and seed production
• Wind protection for lower layers
• Transition between vertical layers

Ecologically valuable native shrubs:

• Vaccinium (blueberry, huckleberry) — native; high fruit value; important Lepidoptera host
• Viburnum spp. — native species; fruit for migratory birds
• Sambucus canadensis (elderberry) — native; very high wildlife value
• Ilex verticillata (winterberry) — native; spectacular winter fruit
• Lindera benzoin (spicebush) — native; host for spicebush swallowtail; shade tolerant
• Morella (Myrica) pennsylvanica (bayberry) — native; highly deer resistant; high bird value

Layer 4: Herbaceous layer (1—3 ft)

Perennials, ferns, and bulbs growing beneath the shrub layer.

Shade-tolerant native perennials:

• Aquilegia canadensis (columbine) — early spring; hummingbird nectar
• Mertensia virginica (Virginia bluebells) — spring ephemeral; blue flowers
• Trillium spp. — woodland wildflowers; very slow to establish from transplant
• Cimicifuga (Actaea) spp. — late summer; tall; white flowers
• Polemonium reptans (Jacob's ladder) — spring bloom; shade tolerant
• Geranium maculatum (wild cranesbill) — self-seeds; lavender flowers

Layer 5: Ground layer (0—12 in.)

Creeping or very low plants that cover bare soil. Per Penn State Extension:

Native ground covers:

• Carex pensylvanica — best native dry-shade ground cover in eastern US; slow to establish but dense once established
• Gaultheria procumbens (wintergreen) — native; low; red berries; zones 3—7; acid soil
• Pachysandra procumbens (Allegheny spurge) — native alternative to invasive Japanese pachysandra; per NC State, more deer resistant
• Asarum canadense (wild ginger) — native; heart-shaped leaves; slow; very effective in shade

Optional: Vine layer

Vertical integration using climbing plants on trees, fences, or structures:

• Parthenocissus quinquefolia (Virginia creeper) — native; spectacular fall color; very high bird value
• Lonicera sempervirens (trumpet honeysuckle) — native; hummingbird plant; non-invasive unlike L. japonica
• Campsis radicans (trumpet vine) — native; hummingbird; aggressive; use only with space to spread