Planting Under Trees: What Grows Well Beneath a Canopy

Why planting under trees is hard

The ground beneath a tree is a tough place for other plants. They face shade, roots that take up most of the available water, and soil that may be dry, compacted or full of roots. At the same time, the tree has its own needs. Most of its feeding roots lie in the upper layer of soil, where disturbance and added soil can do harm.

The goal is to add plants that tolerate dry shade while making as little change to the soil as possible.

Protect the roots first

Avoid cutting large roots. If you hit a thick root while digging, move the planting hole rather than cutting it. A common guideline is to avoid cutting roots larger than about the thickness of a pencil, and to leave large structural roots alone. Cutting them can destabilize the tree and open it to decay.
Use hand tools. A trowel is gentler than a spade, which can nick roots and bark.
Do not use herbicides to clear the area. Chemicals can be taken up by the tree roots.
Do not rototill. Tilling tears the shallow roots.

Prepare the area

Clear grass and weeds by hand. Use a trowel or hand tools.
Do not build a raised bed. Piling soil or compost over the roots can reduce the oxygen they need. Extension guidance generally recommends adding no more than about 2 inches of soil or compost, if any.
Keep the trunk clear. Leave roughly a foot of space around the trunk free of added soil, and never bury the root flare. Wet soil against the bark can cause rot.
Choose small plants. Plugs and small pots (quart size or 4-inch) need smaller holes than gallon-size shrubs and are easier to place between roots.

Plants that tolerate dry shade

Look for plants labeled for dry shade, and check that they suit your region. Once established, these often cope well.

Perennials: hostas, barrenwort (epimedium), brunnera, Lenten rose (helleborus), bigroot geranium and coral bells (heuchera).
Ferns: Christmas fern and other tough, drought-tolerant ferns.
Sedges and grasses: many carex species are used as a lawn-like cover.
Groundcovers: ajuga, creeping raspberry and barrenwort. Some groundcovers spread aggressively, so check how a plant behaves in your region before using it.
Spring ephemerals: woodland plants such as bloodroot, Virginia bluebells and bleeding heart emerge and bloom before the tree leafs out, then go dormant.
Bulbs: spring-flowering bulbs such as snowdrops and daffodils also bloom before the canopy closes.

Planting a few types in drifts looks more natural, and is easier to maintain, than many different plants scattered around.

Trees that need extra thought

Black walnut. The roots and other tissues produce a compound that harms many plants. Choose plants known to tolerate walnut.
Shallow-rooted trees. Species with roots at the soil surface, such as many maples, leave little room for digging, and the roots can outcompete new plants. Often a layer of mulch is the better choice than planting. See are maple trees messy for how maple roots behave.
Young trees. A newly planted tree is still establishing; give it its own space and mulch before adding other plants.

Planting and watering step by step

Place the plant, still in its pot, where you want it to check the spacing.
Dig a hole just large enough for the root ball, shifting it if you hit a large root.
Set the plant at the same depth as it grew in the pot and backfill with the soil you removed.
Water well. New plants beneath trees need regular watering through the first season or two because the tree takes much of the moisture.
Mulch lightly, keeping it away from the trunk.

Mulch or plants at the base?

Right against the trunk, a ring of mulch is usually better than plants. A layer of organic mulch a few inches deep, pulled back from the trunk, protects roots and limits weeds. For choosing mulch, see our guide on cedar mulch around fruit trees, which covers general mulching practice too.

About the rules of thumb

Readers often ask about the “10/20/30 rule” and the “3-5-7 rule”. These names are used inconsistently in landscaping, and we could not find a single standard definition for either. The 3-5-7 idea usually refers to grouping plants in odd numbers for a balanced look. For anything about tree health, rely on the root-protection guidelines above: limited added soil, no cutting of large roots and a clear zone around the trunk.

Timing

Spring and fall are generally good times to add understory plants, when cool weather reduces stress. See our guide on seasons for planting for more on timing.

Frequently asked questions

What is the best thing to plant under a tree? Dry-shade perennials, ferns and sedges suited to your region are common choices. Which is best depends on the tree, the light and your climate.

How deep can I add soil? Extension guidance generally says no more than about 2 inches of soil or compost, and none within about a foot of the trunk.

Can I plant grass under a tree? Grass struggles in dense shade and competes with tree roots. A shade groundcover or mulch is usually easier.

What is the best thing to put around the base of a tree? A ring of organic mulch, a few inches deep and pulled back from the trunk, is a standard answer.