If you’ve ever tried planting something beneath a tree—or grow grass there for that matter—you’ve probably wondered if it was actually possible to grow anything successfully in such a shady, full-of-roots location.

While it’s true that planting under a tree does present challenges, that doesn’t mean it’s more trouble than it’s worth.

Any plants sharing soil will compete with one another for resources, whether that’s water, nutrients, or even a place to spread their roots. Since trees are just very big plants, they’re likely going to win that competition compared with those of much smaller size growing beneath them. The trick is to provide enough of what they need for both a tree and its companions to share and grow successfully.

Sometimes, the problem isn’t just competition for resources. Some trees are allelopathic, meaning that they produce a substance that actively discourages the growth of other plants. Black walnut trees (Juglans nigra)—roots, leaves, and nut hulls—secrete a toxin called juglone which does just that. Even so, plants such as wild ginger (Asarum canadense), ostrich fern (Matteuccia struthiopteris), and serviceberry (Amelanchier spp.) are suitable to grow beneath black walnut trees. 

Of course, if your tree is not among those that are allelopathic, you’ll have more options in choosing shrubs, perennials, and groundcovers that are shade-tolerant, drought-tolerant, and have shallow root systems.

Consider small spring-blooming bulbs such as snowdrops (Galanthus), grape hyacinth, (Muscari armeniacum), and squill (Scilla siberica) for flowers and color in early spring before trees are fully leafed out. Small bulbs, planted individually, can be easily nestled among tree roots with little disruption. 

Shade tolerant perennials such as hosta (Hosta), lady's mantle (Alchemilla mollis), fringed bleeding heart (Dicentra eximia), foamflower (Tiarella), or coral bells (Heuchera) can produce attractive displays as a mass planting or as part of a mixed group with a variety of color, leaf shape and texture. Selecting perennials, rather than annuals, can avoid the need to repeatedly disturb roots by replanting each year.

A tree is surrounded by a mulched area planted with many different varieties.
A garden established under a mature tree can create interest to a home landscape. Photo by Amy Simone. 

Once you’ve selected what you’d like to plant beneath a tree, hand-pull any weeds and use a hand trowel to remove grass.

Keep in mind that the planting area may be congested with roots of various sizes and that the health of the tree depends on them. Avoid using spades, shovels, or other large digging instruments that could cut, nick, or otherwise damage those roots. Don’t cut or remove larger roots. While thin, fibrous roots can regrow, damage to larger roots takes much longer and risks the health of the tree through disease or insect infestation. 

For best results, select starter-sized plants and dig a hole just large enough to accommodate the root ball. If the tree’s roots present a barrier to digging, try another area nearby. Plant, then fill the hole with soil and water well. 

After you’ve finished planting beneath the tree, apply a thin layer of mulch to help retain moisture. Be sure to avoid covering any above-ground roots and leave an area at least 3 inches (or more) from the trunk free from mulch to protect the root flare.

During the hot summer months, a weekly, deep watering will help ensure there will be enough water to satisfy thirsty young plants and the tree, too.

When you’re done, pull up a chair, sit back, relax, and enjoy the shade and the new plants there.

For answers to your home gardening questions, contact the University of Vermont Extension Master Gardeners Helpline online at https://go.uvm.edu/gardenhelpline or by phone at 802-656-5421 on Thursdays from 9 a.m. to 12 p.m..