Mulching

Mulching enriches and 

protects soil, helping provide a

better growing environment.

In your backyard

Mulching is one of the simplest and

most beneficial practices you can

use in the garden. Mulch is simply a

protective layer of a material that is

spread on top of the soil. Mulches

can either be organic--such as grass

clippings, straw, bark chips, and similar materials--or inorganic--such as

stones, brick chips, and plastic. Both

organic and inorganic mulches have

numerous benefits.

Mulch:

• protects the soil from erosion

• reduces compaction from the

impact of heavy rains

• conserves moisture, reducing the

need for frequent waterings

• maintains a more even soil temperature

• prevents weed growth

• keeps fruits and vegetables clean

• keeps feet clean, allowing access

to garden even when damp

• provides a "finished" look to the

garden

Organic mulches also improve the

condition of the soil.As these

mulches slowly decompose, they

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Conservation Districts

Wildlife Habitat Council

April 1998

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One in a series of 10 tip sheets on backyard conservation

Backyard

Conservation

Mulching works in gardens, around

trees and shrubs, and in other areas.
provide organic matter which helps

keep the soil loose.This improves

root growth, increases the infiltration

of water, and also improves the

water-holding capacity of the soil.

Organic matter is a source of plant

nutrients and provides an ideal environment for earthworms and other

beneficial soil organisms.

While inorganic mulches have their

place in certain landscapes, they lack

the soil improving properties of

organic mulches. Inorganic mulches,

because of their permanence, may

be difficult to remove if you decide

to change your garden plans at a

later date.Therefore, this tip sheet is

limited to the use of organic

mulches.

Mulch materials

You can find mulch materials in your

own yard! Lawn clippings make

excellent mulch.While not particularly attractive for a flower bed, they

work wonderfully in the vegetable

garden.The fine texture allows them

to be spread easily even around

small plants. However, grass clippings are becoming scarce because

of the increased popularity of

mulching lawnmowers that provide

many of the same benefits of

mulching to lawns. Newspaper, as a

mulch, works especially well to control weeds. Leaves are another readily available material to use as mulch.

Leaf mold, or the decomposed

remains of leaves, gives the forest

floor its absorbent spongy structure.

Compost makes a wonderful mulch

if you have a large supply. Compost

not only improves the soil structure

but provides an excellent source of

plant nutrients.

Bark chips and composted bark

mulch are available at garden centers.These make a neat finish to the

garden bed and will eventually

improve the condition of the soil.

These may last for one to three years

or more depending on the size of

the chips or how well composed the

bark mulch is. Smaller chips tend to

be easier to spread, especially

around small plants. Depending on

where you live, numerous other

materials make excellent mulches.

Hay and straw work well in the vegetable garden, although they may

harbor weed seeds. Seaweed mulch,

ground corn cobs, and pine needles

can also be used. Pine needles tend

to increase the acidity of the soil so

they work best around acid-loving

plants such as rhododendrons and

blueberries.

When to apply

mulch

Time of application depends on

what you hope to achieve by

mulching. Mulches, by providing an

insulating barrier between the soil

and the air, moderate the soil temperature.This means that a mulched

soil in the summer will be cooler

than an adjacent unmulched soil;

while in the winter, the mulched soil

may not freeze as deeply. However,

since mulch acts as an insulating

layer, mulched soils tend to warm up

more slowly in the spring and cool

down more slowly in the fall than

unmulched soils.

If you are using mulches in your vegetable garden or flower garden, it is

best to apply them after the soil has

warmed up in the spring. Cool, wet

soils tend to slow seed germination

and increase the decay of seeds and

seedlings.

If adding additional layers of mulch

to existing perennial beds, wait until

the soil has warmed completely.

Mulches used to help moderate winter temperatures can be applied late

in the fall after the ground has

frozen but before the coldest temperatures arrive. Applying mulches

before the ground has frozen may

attract rodents looking for a warm

over-wintering site. Delayed applications of mulch should prevent this

problem as, hopefully, the creatures

would already have found some

other place to nest! 

Mulches used to protect plants over

winter should be loose material such

as straw, hay, or pine boughs that will

help insulate the plants without

compacting under the weight of

snow and ice. One of the benefits

from winter applications of mulch is

the reduction in the freezing and

thawing of the soil in the late winter

and early spring.These repeated

cycles of freezing at night and then

thawing in the warmth of the sun

cause many small or shallow rooted

plants to be heaved out of the soil.

This leaves their root systems

exposed and results in injury or

death. Mulching helps prevent rapid

fluctuations in soil temperature and

reduces the chances of heaving.

Applying mulch

1. Begin by asking yourself the following questions.

a.What do I hope to achieve by 

mulching? 

Weed control?

Moisture retention?

Soil improvement?

Beautification?

b. How large is the area to be 

mulched?

c. How much mulch will I need to

cover the area?

Mulch is measured in cubic feet.

As an example, if youhave an area

10 feet by 10 feet and you wish

to apply 3 inches of mulch, you

would need 25 cubic feet.

(10' x 10' x .25' = 25 cu. ft.)

2. Determine what mulch material to

use and purchase or accumulate

what you need.

a. Mulch can often be purchased

bagged or bulk from garden centers. Bulk may be cheaper if you

need large volumes and have a

BACKYARD Mulching

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way to haul it. Bagged mulch is

often easier to handle, especially

for smaller projects. Most bagged

mulch comes in 3-cubic feet

bags.

b. Compost--

Refer to the tip sheet on composting for information on how

to make your own compost.

c. Leaves--

1. Collect leaves in the fall.

2. Chop with a lawnmower or

shredder.Whole leaves tend to

compact if wet or blow away if

dry. Chopping will reduce the

volume and facilitate composting.

3. Compost leaves over winter.

Some studies have indicated that

freshly chopped leaves may inhibit the growth of certain crops.

Therefore, it may be advisable to

compost the leaves over winter

before spreading them.

d. Grass clippings–

1. Spread them immediately to

avoid heating and rotting.

e. Newspaper–

1. Save your own newspapers.

BACKYARD Mulching

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Bark mulch 

Wood chips

Leaves

Grass clips

Newspaper

Compost

Mulch materials

Notes 

Smaller chips are easier to spread, especially around small plants. Excellent for use

around trees, shrubs, and perennial gardens.When spreading mulch around trees,

keep the mulch an inch or two away from the trunk.A couple inches of mulch is

adequate.There is no need to apply the mulch 6 or 8 inches high, as often is seen.

Similar to bark mulch. If using fresh wood chips that are mixed with a lot of

leaves, composting may be beneficial.

Best to chop and compost before spreading. If using dry leaves, apply about six

inches deep.

Thicker layers tend to compact and rot, becoming quite slimy and smelly. Add

additional layers as clippings decompose. Do not use clippings from lawns treated

with herbicides.

Apply sheets of newspaper and cover lightly with grass clippings or other mulch

material to anchor. If other mulch materials are not available cover edges of paper

with soil. Applying on a windy day can be a problem.

Excellent material for enriching soil.

Amount to Apply

2-4 inches

2-4 inches

3-4 inches

2-3 inches

1/4 inch

3-4 inches
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2. Use only newspaper text pages

(black ink); color dyes may be

harmful to soil microflora and

fauna if composted and used.

3. Use 3 or 4 sheets together,

anchored with grass clippings or

other mulch material to prevent

blowing away.

3.The amount of mulch to apply will

be determined by the mulch material

you are using.

General Guidelines:

a. Do not apply mulch directly in

contact with plants. Leave an

inch or so of space next to plants

to help prevent diseases flourishing from excessive humidity.

b. Remove weeds before spreading

mulch.

Bark mulch and wood chips are

sometimes used with landscape fabric or plastic.The fabric or plastic is

laid on top of the soil and then covered with a layer of bark chips.A

caution to this practice: while the

plastic or fabric may initially provide

additional protection against weeds,

as the mulch breaks down, weeds

will start to grow in the mulch itself.

The barrier between the soil and the

mulch also prevents any improvement in the soil condition and makes

planting additional plants more difficult.

For sources of

mulch

Check under mulches or garden centers or nurseries in the Yellow Pages.

Your local community may also have

wood chips from the removal of

street trees that are available free to

residents.

On the farm

Farmers use mulches in many ways.

Conservation tillage is a common

practice that creates a mulch on the

soil surface. Unlike the once common practice of plowing all crop

residue into the soil, conservation

tillage leaves the crop residue on top

of the soil.These pieces of corn

stalk, straw, or bean stems help protect the soil against wind and water

erosion. Corn crops harvested for

grain return large amounts of residue

to the soil surface and are more

effective in preventing soil erosion

than crops with less residue such as

soybeans.

Mulching is a common practice

among strawberry growers in northern climates. In this situation, mulch

is used to protect the crop during

the winter and to help prevent early

blooming of the plants. Plants that

bloom too early are more likely to be

damaged by spring frosts.The mulch

also helps keep the berries cleaner,

protecting them from soil splashing

on them in the rain.

Inorganic mulches are also widely

used in commercial agriculture. Clear

plastic mulch can be particularly

beneficial in giving warm season

crops a head start.The clear plastic

acts as a mini-greenhouse, warming

the soil underneath it. Particularly

where early sweet corn brings a premium price, this practice can give a

grower a couple of weeks head start.

Also, research is showing that leaving crop residues helps hold carbon

in the soil and aids in reducing

greenhouse gases.

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