How to Mulch Trees, Shrubs and Garden Beds Correctly

Why Mulch Matters

A properly applied layer of mulch can help conserve soil moisture, moderate soil temperature, reduce weed growth and protect landscape plants from lawn equipment.

Mulch also gives landscape beds a clean, finished appearance. Natural mulch gradually breaks down and contributes material to the surface of the soil.

Mulch is beneficial, but more is not better. Excessive mulch or mulch piled against trunks and stems can retain too much moisture, restrict air movement and conceal developing plant problems.

Remember: wide, shallow and away from the trunk

Maintain approximately 2 to 3 inches of mulch, spread it over as much of the root area as practical and leave visible space around trunks, stems and plant crowns.

Benefits of Mulch

Conserves Moisture

Mulch reduces evaporation from the soil surface, helping the soil remain evenly moist for longer periods.

Moderates Temperature

A proper layer helps protect plant roots from rapid changes in soil temperature during hot summers and cold winters.

Reduces Weeds

Mulch blocks sunlight from reaching many weed seeds and makes young weeds easier to remove.

Protects Trees

A broad mulch ring keeps lawn mowers and string trimmers away from vulnerable tree trunks and surface roots.

Supports the Soil

Natural mulch slowly decomposes and contributes material to the soil surface.

Improves Appearance

Mulch provides an attractive, coordinated finish around trees, shrubs and garden beds.

How Deep Should Mulch Be?

For most trees, shrubs and established landscape beds, maintain a total mulch depth of approximately 2 to 3 inches.

Always measure the mulch already in the bed before adding more. If 2 to 3 inches remain, loosen and rake the existing material instead of applying another full layer.

Planting Area	Recommended Depth	Important Consideration
Established trees	Approximately 2 to 3 inches	Keep mulch several inches away from the trunk and leave the root flare visible.
Newly planted trees	Approximately 2 to 3 inches	Spread mulch over the planting area without placing it against the trunk.
Shrubs	Approximately 2 to 3 inches	Keep mulch away from the main stems and shrub crown.
Perennial beds	Approximately 1 to 2 inches	Use a lighter layer around small plants and emerging shoots.
Annual flower beds	Approximately 1 to 2 inches	Avoid burying stems or covering newly planted flowers.

Measure the existing mulch before adding more

Do not automatically add a complete new layer every spring. Loosen the existing mulch and add only enough to restore the proper overall depth.

How to Mulch Around a Tree

Create a wide, flat mulch ring around the tree. A wider ring protects more of the root area, reduces competition from grass and helps prevent lawn-equipment damage.

Tree-mulching steps

Carefully remove weeds and grass without damaging the trunk or surface roots.
Locate the root flare, where the trunk naturally widens before meeting the main roots.
Pull away any soil or old mulch covering the root flare.
Spread mulch in a wide, reasonably level ring.
Maintain an overall depth of approximately 2 to 3 inches.
Pull the mulch several inches away from the tree trunk.
Extend the mulch ring outward instead of making it deeper near the trunk.

The finished mulch ring should look like a flat doughnut with an open center—not a volcano or pyramid.

How to Mulch Around Shrubs

Spread mulch evenly beneath and around shrubs while leaving space around their main stems. Avoid burying lower branches or allowing mulch to collect inside the center of the shrub.

Maintain an even layer approximately 2 to 3 inches deep.
Leave visible space around the main stems and shrub crown.
Do not cover the original soil line.
Extend mulch throughout the bed instead of creating individual piles.
Check drip-irrigation lines before covering them.

How to Mulch Garden Beds

In mixed shrub, perennial and annual beds, spread mulch between the plants without covering stems, crowns or emerging shoots.

Remove established weeds before spreading mulch. Mulch can suppress many new weed seedlings, but it will not eliminate mature perennial weeds already growing in the bed.

Keep mulch away from perennial crowns.
Do not bury low-growing plants or groundcovers.
Use a thinner layer around small and newly emerging plants.
Do not pile mulch against fences, siding or wooden structures.
Complete edging before spreading the final layer.

Why Mulch Volcanoes Are Harmful

A mulch volcano is a tall mound of mulch piled directly against a tree trunk. Although this is commonly seen, it is not a correct mulching technique.

Tree trunks are not roots and should not remain buried in damp mulch. Mulch piled against a trunk can keep the bark wet, conceal decay, encourage roots to grow into the mulch and make the tree’s original soil level difficult to identify.

If the trunk looks like a telephone pole entering the ground

The root flare may be buried beneath soil or accumulated mulch. Carefully uncover the flare before adding more mulch, taking care not to damage the trunk or roots.

What to Do With Existing Mulch

Existing natural mulch does not necessarily need to be removed every year. Inspect its depth and condition first.

Pull old mulch away from trunks, stems and plant crowns.
Measure the total depth in several parts of the bed.
Break apart areas that have become crusted or matted.
Remove material if the existing layer is too deep.
Add only enough new mulch to restore the proper depth.

If the bed already contains 3 inches of mulch, adding another 3 inches can create a damaging 6-inch layer.

How Much Mulch Do You Need?

Basic calculation

Multiply the bed’s length by its width to calculate square footage. Multiply that number by the desired depth in feet and divide by 27 to convert the result to cubic yards.

Cubic yards = length × width × depth in feet ÷ 27

For a 2-inch layer, use 0.167 feet. For a 3-inch layer, use 0.25 feet.

Mulch Amount	Coverage at 2 Inches	Coverage at 3 Inches
1 cubic yard	Approximately 162 square feet	Approximately 108 square feet
2 cubic yards	Approximately 324 square feet	Approximately 216 square feet
3 cubic yards	Approximately 486 square feet	Approximately 324 square feet
5 cubic yards	Approximately 810 square feet	Approximately 540 square feet

Irregular beds, existing mulch and changes in grade can affect the final quantity. Measure each section separately and subtract patios, walkways and other areas that will not receive mulch.

Should Landscape Fabric Be Used Under Mulch?

Landscape fabric may be useful beneath decorative stone in certain applications, but it is generally less useful beneath natural mulch in active planting beds.

Natural mulch gradually breaks down, and weeds can eventually germinate in the material that collects above the fabric. Fabric can also become difficult to work around as plants spread and roots grow.

Never wrap landscape fabric tightly around trunks or stems. Fabric should not be used as a substitute for removing weeds and preparing the bed correctly.

Common Mulching Mistakes

Piling mulch against tree trunks
Creating tall mulch volcanoes
Applying more than the recommended depth
Adding new mulch without measuring the existing layer
Burying the tree’s root flare
Covering shrub stems and perennial crowns
Spreading mulch over established weeds
Allowing mulch to touch siding or wooden structures
Damaging surface roots while removing grass
Depending on mulch instead of properly watering new plants

Maintaining Mulched Beds

Inspect mulched areas several times throughout the growing season. Pull mulch away from trunks and stems, remove weeds before they produce seeds and loosen any areas that have become compacted.

Natural mulch gradually decomposes. Replenish it only when necessary to restore the proper depth—not simply because another season has begun.

Mulch does not replace watering

Newly planted trees and shrubs still require regular moisture checks and deep watering. Check the soil beneath the mulch instead of judging moisture by the appearance of the surface.