How to Grow Grass and Plants Under Trees

Having a lush green lawn and vibrant garden beds is the dream for many homeowners. However, this can be challenging to achieve when you have large trees on your property. Trees provide wonderful shade and beauty, but their dense canopy and extensive root systems often make it difficult for grass and plants to thrive underneath them. With some planning and care, it is possible to grow a healthy landscape around your trees.

Test the Soil

The first step is testing your soil to understand what you are working with. Soil samples should be taken from multiple spots under the tree canopy and sent to your local agricultural extension office for analysis. This will provide details on the soil pH, nutrient levels, and composition.

Soil under trees tends to be deficient in nutrients and organic matter. It is also often compacted from the tree’s roots and acidic from fallen leaves and needles. Getting a soil test allows you to identify any problem areas and amend the soil properly to support lawn and plants.

Improve Drainage

Poor drainage is one of the biggest obstacles to growing plants under trees. With their deep roots taking up moisture, tree canopies blocking rainfall, and natural compaction, these areas are prone to becoming waterlogged.

Improving drainage should be a priority. For lawns, core aeration can help punch holes in the soil to allow better water movement. For garden beds, adding organic materials like compost to the soil creates a lighter texture. Consider using raised beds filled with an amended soil mix to provide better aeration and drainage.

French drains or drain tiles can also be installed to help move excess water away from tree root zones more quickly. Level any sloped areas to prevent runoff pooling under trees.

Amend the Soil

Most trees have a web of fine feeder roots that spread right under the soil surface. These are easily damaged by digging and soil amendments. The best way to improve the soil without harming tree roots is to simply apply organic materials on top.

Aged manure, compost, leaf mold, and wood chips are fantastic options. Apply 2-4 inches over the soil surface under trees, keeping materials a few inches away from the trunk. Over time, this mulch will decompose and nourish the soil. Worms and beneficial microbes will also move it down into the ground naturally.

For new garden beds, raised beds with imported soil are another method to give plants better growing conditions. Just be cautious installing these near trees, as any digging risks cutting major roots.

Fertilize Appropriately

Your soil test report will provide fertilizer recommendations tailored to what nutrients are lacking in your soil. When fertilizing under trees, some special considerations are needed:

Use organic or slow-release fertilizers that won’t easily leach or burn sensitive roots. Mixed into the soil amendments, compost and manure provide slow but steady nutrition.
Avoid excessive nitrogen, which can promote invasive surface roots. A balanced fertilizer with macronutrients and micronutrients is ideal.
Focus on the tree’s root zone outward from the trunk when fertilizing. This is where feeder roots are most concentrated.
Reduce fertilizer amounts compared to open lawns and garden beds. Too much can overload the soil profile.
Avoid fertilizing around trees in late summer/fall when they are storing nutrients for dormancy. Focus on spring/early summer feeding.

Select Shade-Tolerant Species

When choosing lawn grass, groundcovers, flowers, and other plants, make sure to select varieties labeled as shade-tolerant. Each plant has different light requirements, so do your research. As a rule of thumb:

Lawn grasses: Fine fescues, acadian grass, and yarrow are low-maintenance options. Avoid sun-loving bluegrass.
Groundcovers: Sweet woodruff, foamflower, ginger, and lilyturf grow well in shade.
Perennials: Astilbe, coral bells, hostas, bleeding hearts, and hellebore thrive in shade.
Annuals: Begonias, impatiens, coleus, and caladiums add color.

Placing shade plants where they will get morning sun and afternoon shade is ideal. Avoid Regimented rows; instead, let plants intermingle to form natural-looking drifts.

Provide Supplemental Lighting

For plants that need more sunlight than what filters through, supplemental lighting can help. Installing full-spectrum LED grow lights in nearby trees or posts gives you flexibility. Use a timer to set the lights to turn on before sunrise and turn off after sundown, extending daylight hours. This extra lighting is especially useful for vegetable gardens under trees.

Use Containers

Container gardening is an excellent way to give plants the soil, moisture, and light conditions they need in shady tree spots. Use large self-watering pots, raised beds, and even half whiskey barrels for vegetables and ornamentals. Grouping containers together creates a lovely intimate garden.

Focus on shade-loving edibles like lettuce, spinach, kale, chard, and herbs. Containers can always be shifted around as needed to give plants the best light exposure.

Grass Alternative Groundcovers

If you are struggling to grow a lush lawn under dense tree canopies, alternative groundcovers may be the solution. These plants tolerate shade, foot traffic, and require less maintenance than traditional grass. Some options include:

Clover: Available as white and Dutch clover, mixes well with grass and fixes nitrogen.
Creeping thyme: Dense, cushion-forming thyme has edible leaves and flowers. Tolerates light foot traffic.
Wild ginger: Low, spreading wild ginger has pretty heart-shaped leaves. Grows well in dry shade.
Creeping phlox: Evergreen phlox forms a colorful carpet of flowers in spring.
Sweet woodruff: Fragrant groundcover for shady spots. Provides excellent weed suppression.

Use groundcovers alone or mix with resilient grass varieties. They offer habitat for pollinators and add visual interest. Just be sure selected plants are not aggressive spreaders that will take over.

Use Organic Weed Control

Weed control is always a challenge when growing plants under trees. Deep tree roots often prevent typical chemical herbicides from working well, plus the shade provides ideal conditions for weeds to thrive.

Organic methods are the best approach under trees:

Apply 2-4 inches of mulch to smother weeds and block light. Replenish as needed.
For lawns, corn gluten meal provides natural pre-emergent weed control. Apply early spring and fall.
Pull weeds by hand frequently to prevent them from setting seed.
For persistent perennial weeds, use a spade to cut roots below soil surface.
Maintain healthy plantings that can outcompete weeds. Address bare or thin areas quickly.
For driveway and patio cracks, use a propane weed torch to kill weeds organically.

Vinegar-based sprays, soap-based herbicides, and clove oil can selectively spot treat tougher weeds. But be cautious using any weed killer under treas to prevent root damage.

Prune Carefully

To maintain plant health and aesthetics under trees, occasional pruning is needed. Take care to do this without harming the tree:

Do not top trees or remove large branches without an arborist’s advice. Improper pruning stresses trees and can lead to disease.
Make clean cuts just outside branch collars and avoid leaving stubs.
Only prune dead, damaged or crossing/rubbing branches. Never remove more than 25% of living canopy in a season.
Paint wounds over 2 inches diameter with tree-pruning sealer to prevent infections.
Disinfect pruning tools between trees/plants to prevent disease spread.
Prune in late winter to shape and improve form. Avoid major summer pruning.
Space cuts apart evenly and avoid removing inner foliage to maintain outward canopy shape.
Shaping and thinning inner growth helps sunlight filter through to plants below.

Provide Adequate Water

Trees and plants under them need supplemental water when rainfall is insufficient. Soaker hoses, drip irrigation, or sprinklers on low pressure settings are best for deep watering without runoff.

1-2 inches of water per week is needed for lawns, ideally split into 2-3 sessions.
Established trees require deep monthly soaking from spring through fall (10-15 gallons per inch of trunk diameter).
Hand water containers and new plantings, avoiding tree trunks and major surface roots.
Water early morning to reduce evaporation and mold/mildew.
Mulch gardens to retain moisture and reduce watering needs.
Adjust amounts based on weather and soil drainage.

Consider Professional Care

If you are still struggling to grow healthy plants under mature tree canopies, engaging a professional may help. Consulting an ISA certified arborist and landscape designer can provide tailored solutions for your unique property.

Services may include:

Strategic limb removal/thinning to improve light penetration while protecting tree health.
Air spading radial trenching that oxygenates soil without damaging roots.
Vertical mulching techniques that drill holes and backfill with amendments.
Radial mulch applications that spread materials away from trunks.
Targeted soil de-compaction and drainage improvements.
Custom plant selection and placement for optimal growth.

While spending some money up front, the right professional improvements will pay off for years to come by establishing better growing conditions. A thriving landscape under your trees adds tremendous value and enjoyment to any property.

Frequently Asked Questions About Growing Grass and Plants Under Trees

How do I grow grass under pine trees?

Choose shade-tolerant grass varieties like fine fescue and apply acid fertilizers formulated for pine trees. Aerate soil, top-dress with compost, and dethatch to remove fallen needles. Grasses may still be thin or sparse under dense pines. Consider alternative groundcovers like clover or phlox.

Should I remove tree roots to plant flowers?

Removing large woody roots risks destabilizing or killing the tree. Digging also damages the tree’s root system. Instead, build raised planting beds over surface roots, amending just the soil inside them. Or use containers for flowers and small shrubs near trees.

How close can I plant to an existing tree?

Avoid planting right against tree trunks where dense feeder roots grow. Leave a surrounding open ring 2-3 feet out from the trunk unplanted. For saplings, leave at least a 3 foot radius clear. Any digging should be shallow and avoid severing major woody roots.

What is the best fertilizer to use under trees?

Choose organic slow-release fertilizers like compost, manure, bone meal, worm castings, or mixed natural formulas. Apply over the soil surface under the tree’s dripline instead of digging in. Reduced nitrogen levels balanced with other nutrients are ideal.

Can I grow vegetables and herbs under trees?

Yes, with proper care many vegetables and herbs can grow in moderate shade. Try lettuce, kale, chard, spinach, arugula, radishes, beets, Brussels sprouts, mint, parsley, oregano, garlic, and chives. Make sure plants get some early morning or late afternoon sun.

What causes bare spots under trees?

Compacted soil, poor drainage, thick roots near the surface, and dense shade cause lawns to thin out under trees. Core aerate, top dress with compost, and overseed with shade-tolerant grass. Alternatives like clover or groundcovers may work better than traditional lawn grasses.

Conclusion

Growing a beautiful landscape under mature trees is very achievable with the right approach. The keys are correcting issues like poor soil, drainage, and light penetration while selecting plants adapted to the unique environment. Patience and persistence are required, as is a tolerance for less than perfection. But the benefits of healthy plants and lush grass around your trees are well worth the effort. With some planning and care, your landscape can gradually transform into an enviable oasis that adds enjoyment, property value, and curb appeal.