How to Landscape Around Trees Without Killing Them

A bare tree trunk sticking out of a lawn looks unfinished. The dirt ring where the mower can’t reach, the exposed surface roots that trip people, the scraggly grass that dies every summer in the shade. Landscaping around your trees fixes all of that. But do it wrong and you’ll slowly kill the tree you’re trying to make look better.

I’ve watched neighbors pile 8 inches of topsoil over their oak roots to plant flowers, then wonder why the tree died three years later. The tree didn’t die from the flowers. It died because 8 inches of fill soil suffocated the roots. The right approach protects the root zone while making the base of every tree in your yard look intentional.

The root zone rules

Before you do anything around a tree, understand what’s underground. Tree roots spread far wider than most people realize, typically 2-3 times the width of the canopy. Most feeder roots sit in the top 12-18 inches of soil. Everything you do in that zone affects the tree.

UF/IFAS Extension identifies incorrect planting depth and root zone disturbance as the most common causes of tree decline. The damage is slow. A tree with suffocated roots may take 3-5 years to show obvious stress, and by then it’s often too late to save it.

What you can safely do in the root zone:

• Spread mulch (at the right depth)
• Plant shallow-rooted perennials and groundcovers
• Set stepping stones on the surface
• Install low-voltage landscape lighting

What will damage or kill the tree:

• Adding more than 2 inches of soil over existing roots
• Digging trenches for edging, irrigation, or wiring
• Compacting soil with heavy equipment or repeated foot traffic
• Removing soil to lower the grade
• Piling fill soil against the trunk

How to mulch around trees correctly

Mulch is the single best thing you can do for a tree. The Arbor Day Foundation reports that a proper mulch ring retains soil moisture, moderates root temperature, suppresses weeds, prevents mower damage, and adds nutrients as it decomposes.

The rules are simple, but almost everybody breaks them:

Depth: 2-4 inches. Not 6. Not 8. Penn State Extension warns that deep mulch applications prevent water and air from reaching roots, promote fungal disease, and can kill trees.

Shape: Donut, not volcano. Leave 3-4 inches of bare space between the mulch and the trunk. The root flare (where the trunk widens at the base) must be visible and exposed to air. Mulch piled against the trunk holds moisture against the bark, which causes decay.

Width: As wide as practical. A 3-foot ring is the minimum. Extending mulch to the drip line is ideal but not always realistic in a small yard. Even a modest ring eliminates mower and trimmer strikes, which are a major source of bark damage on young trees.

Material: Shredded hardwood bark is the standard. Arborist wood chips (free from tree service companies) work well and cost nothing. Avoid dyed mulch, rubber mulch, and rock (rock reflects heat and doesn’t add organic matter). Pine needles work for acid-loving plants but lower soil pH over time.

Why mulch volcanoes kill trees

You see them everywhere: cone-shaped piles of mulch banked 12-18 inches up the trunk. Landscaping crews do this because it looks “finished.” It’s actually the most damaging thing you can do to an otherwise healthy tree.

Penn State Extension documents the cascade of problems:

Bark decay. Tree bark is designed for air exposure, not constant moisture. Wet mulch against bark causes the inner bark (phloem) to decay. The phloem carries sugars from the leaves to the roots. When it dies, the roots starve.

Root suffocation. Excess mulch blocks oxygen exchange. Roots deprived of oxygen stop growing and eventually die. The tree may look fine for a year or two because it has stored energy, but once reserves run out, decline is rapid.

Disease entry. Fungal cankers and root rots thrive in the warm, moist conditions under thick mulch. Cankers can girdle the trunk, cutting off nutrient flow completely.

Rodent damage. Mulch piled against the trunk provides shelter for voles and mice that chew bark in winter. Girdled bark from rodent feeding kills more young trees than most people realize.

Temperatures up to 140 degrees F have been measured inside decomposing mulch piles. This heat can directly kill the phloem of young trees.

If you already have a mulch volcano around your trees, pull the mulch back to expose the root flare. Do it today. It’s the single fastest improvement you can make.

Planting flowers and groundcovers under trees

Planting under trees works if you follow two rules: use shallow-rooted plants and don’t disturb the tree roots.

Clemson HGIC recommends these shade-tolerant perennials for planting under trees:

Hostas are the classic shade plant. They range from miniatures (a few inches tall) to giants (4 feet tall with 20-inch leaves). Clemson’s hosta guide notes they’re long-lived perennials that may outlive their gardeners. Plant them on the north or east side of the tree where they get morning light and afternoon shade. Deer eat hostas aggressively, so if deer visit your yard, choose something else.

Ferns handle full shade better than almost any other plant. Clemson Extension suggests hay-scented, ostrich, and southern shield ferns as groundcovers in shady areas. Cinnamon and royal ferns tolerate more sun if the soil stays moist.

Astilbe produces feathery plumes of pink, red, white, or lavender flowers in partial shade. Clemson notes it’s hardy in zones 3-9 and deer-resistant, making it a solid choice where hostas get eaten.

Lenten Rose (Helleborus orientalis) blooms in late winter when nothing else is flowering. Evergreen foliage, deer-resistant, and thrives in dry shade under established trees. One of the toughest shade perennials you can plant.

Barrenwort (Epimedium) is an excellent choice specifically for dry shade under trees, per Clemson’s shade garden guide. The delicate flowers appear in April, and the heart-shaped foliage stays attractive all season.

Spring bulbs (crocus, snowdrops, scilla, species tulips) work under deciduous trees because they bloom and finish before the tree leafs out. They get full sun in spring when they need it and go dormant before the canopy closes.

For more shade-tolerant species including trees and large shrubs, our shade-tolerant trees guide covers the full range.

How to plant under trees without damaging roots

The biggest risk when planting under trees is cutting through roots with a shovel. A single severed major root can destabilize the tree or introduce disease.

The right method:

1. Scrape back the mulch in the area where you want to plant
2. Use a hand trowel or narrow spade, not a full-size shovel
3. Work between roots, not through them
4. Plant small plugs or 4-inch pots, not gallon containers (smaller plants need smaller holes)
5. Don’t add more than 1-2 inches of compost over the existing soil grade
6. Replace the mulch around the new plants

Do not rototill under a tree. Do not bring in a truckload of topsoil. Do not build a raised bed with sides that trap soil against the trunk. All of these common approaches damage or kill the tree over time.

If you want a more structured look, our article on landscaping and decorating around trees covers border walls, rock gardens, seating areas, and lighting options that don’t require digging into the root zone.

Dealing with surface roots

Surface roots are normal for many tree species. Maples, willows, poplars, and large oaks frequently develop roots that grow above the soil surface, especially in compacted or shallow soils.

The Arbor Day Foundation advises against cutting surface roots or adding soil on top of them. Both approaches damage the tree:

Don’t cut them. Removing a major surface root can destabilize the entire tree and create an entry point for disease. If a surface root is less than 25% of the trunk diameter, it may be safe to remove, but consult a certified arborist first.

Don’t bury them. Adding more than 2 inches of soil over surface roots suffocates them. The roots need air exchange with the atmosphere. Burying them under fill soil is a slow death sentence.

Do mulch lightly. A 2-3 inch layer of mulch between and over surface roots is the safest approach. It smooths out the trip hazards, suppresses weeds, and doesn’t suffocate roots.

Do plant groundcovers. Low-growing plants like vinca, pachysandra, sweet woodruff, or creeping Jenny planted between surface roots soften the look without harming the tree.

For tips on which trees to avoid planting near structures in the first place (the ones with the worst surface root problems), our guide to trees to never plant in your yard covers the usual suspects.

Edging and borders around trees

A clean edge between the mulch ring and the lawn makes the tree base look intentional. But how you create that edge matters.

Safe edging options:

• Steel or aluminum landscape edging set at the soil surface (not dug in deep)
• Natural edge created by cutting a shallow V-trench with a half-moon edger (1-2 inches deep)
• Stacked stone or brick set on the surface or barely recessed

Avoid:

• Concrete curbing that requires a trench through the root zone
• Landscape timbers staked with rebar driven through roots
• Retaining walls that trap fill soil against the trunk

The simpler the better. A clean edge cut with a half-moon edger takes 15 minutes per tree, costs nothing, and looks sharp. Refresh it twice a year (spring and fall) and you’ll never need a hard border.

Soil compaction: the invisible tree killer

Soil compaction is one of the most overlooked causes of tree decline. Compacted soil contains little oxygen, restricts root growth, and prevents water infiltration. UF/IFAS Extension identifies heavy foot traffic, lawn mowers, and construction equipment as the primary causes.

If you’re planning landscaping around a tree, don’t drive equipment over the root zone. Don’t park vehicles under the canopy. Don’t stage building materials on the roots during a construction project.

For trees near patios, walkways, or other high-traffic areas, a generous mulch ring (6-10 feet in diameter) keeps feet off the root zone. Stepping stones set on the surface (not recessed) provide a path without compaction. For broader guidance on seasonal yard care and project scheduling, that month-by-month checklist helps you stay on top of tree maintenance alongside other property tasks.

What about raised beds around trees

Raised beds built against tree trunks are one of the most common landscaping mistakes. The bed walls trap soil and moisture against the bark, the fill soil buries the root flare, and the irrigation for the bed plants keeps the trunk constantly wet.

If you want raised planting near a tree, leave at least 3-4 feet of clearance between the raised bed and the trunk. Build the bed outside the root zone drip line, or use a low, open design (6-8 inches of soil without solid walls) that allows air circulation.

Our spring tree care checklist covers the full routine for maintaining healthy trees, including mulch refresh, fertilizer timing, and when to call an arborist. If you combine good landscaping practices with annual tree maintenance, every tree in your yard should thrive for decades.

Frequently asked questions

What can I plant around the base of a tree? Shade-tolerant perennials like hostas, ferns, astilbe, Lenten rose, and barrenwort. Spring bulbs (crocus, snowdrops) work under deciduous trees. Groundcovers like vinca, pachysandra, and sweet woodruff fill in between surface roots. Avoid plants that need full sun or deep planting holes.

How much mulch should I put around a tree? Two to four inches, spread from 3-4 inches away from the trunk out to the drip line. Never pile mulch against the trunk (mulch volcano). University extension services consistently recommend this range for both moisture retention and root health.

Will planting flowers under a tree kill it? Not if you plant correctly. Use small plants (4-inch pots), dig with hand tools between roots, don’t add more than 1-2 inches of soil, and don’t cut or sever roots. The flowers themselves won’t hurt the tree. The digging and soil addition is what causes damage when done carelessly.

My tree has surface roots everywhere. What should I do? Spread 2-3 inches of mulch over and between the roots. This is the safest approach. Don’t cut the roots and don’t bury them under fill soil. Plant low groundcovers between roots for a finished look. If roots are causing structural damage to walkways or foundations, consult a certified arborist.

Should I fertilize the area around my tree after landscaping? Mulch provides slow-release nutrients as it decomposes. Additional tree fertilizer is only needed if the tree shows signs of nutrient deficiency (yellowing leaves, slow growth, small leaves). Over-fertilizing is more common than under-fertilizing and can push weak growth that’s susceptible to pests and disease.