The many facets of mulch


Crocuses poke through leaf mulch in spring.


Straw keeps the weeds down at this flower farm.


Wood chips make the maintenance of this long bed much easier.


Homeowners use rock to mulch tree and shrub beds.


Biodegradable plastic keeps the weeds from poking through the surface.


Recycled jute-backed carpet works as an effective weed barrier.

Mulch is a material that covers the soil and/or plants. When spread on soil in summer it preserves moisture, keeps weeding to a minimum and maintains a constant soil temperature. In late fall and winter mulch is used to cover the roots and sometimes stalks of tender plants, protecting them from the extreme cold and changing temperatures.

Many different materials can be used as a mulch, some being organic, others man made. Cost, availability, aesthetics, ease of use are all important when choosing a mulch.

Mulch is not completely maintenance free. Dust, dirt and seeds will blow into any mulch. It is important to remove weeds as soon as they germinate to keep the mulch pristine.

Peat moss

Peat moss works best in vegetable gardens, annual and perennial beds as the plants will keep the peat moss in place. Works well as a winter mulch. It is best used mixed in soil or with another mulch such as straw or grass clippings.

Advantages

• Readily available in two or four cubic foot bails
• Light weight and easy to spread
• Improves soil structure
• Absorbs and holds moisture
• Easy to work into the soil
• Rarely weedy

Disadvantages

• Light weight; blows in the wind if it is dry
• Hard to moisten once it becomes dry
• It is widely considered a non-renewable resource, though new peat accumulates naturally in more than replacement amounts

Coconut fiber or chips

Coconut husk is starting to be used to replace peat moss. Like peat moss it can be used to insulate plants during the winter months. It is best used incorporated in soils that need hydration and in containers.

Advantages

• Light weight and easy to spread
• Improves the soil structure
• Absorbs and holds moisture – up to three times as much as peat.
• Easy to work into the soil
• Never weedy
• Breaks down very slowly (five to seven years)
• A renewable resource
• Winter mulch can be worked into the soil
• Easier to rehydrate than peat moss

Disadvantages

• Light weight and blows in the wind if it is dry
• Expensive unless recycled from a hydroponics operation
• Not always available

Wood chips

Wood chips are ideal for spreading around shrubs, trees and long-term perennials.

Advantages

• Readily available from sawmills, pruning companies or garden centres
• Easy to spread
• Chippers can be rented or purchased to produce your own product
• Can be spread thickly to keep weeds out
• Small chips will break down producing humus
• Attractive

Disadvantages

• Small chips will break down and need to be refurbished
• When chips decompose they use the nitrogen in the soil, slowing plant growth
• After a number of years the chips pack, making it hard for water or air to penetrate
• Hard to weed without getting slivers
• Larger chips sold in bags are expensive

Straw

Straw is often used in market gardens or vegetable gardens between rows of produce or around fruit and melons to keep the produce clean. Straw can also be used as a winter mulch.

Advantages

• Inexpensive
• Keeps produce clean
• Can be dug into vegetable bed soil in the fall

Disadvantages

• Straw can contain weed /grain seeds
• Unsightly
• Grain seeds attract rodents
• Wet straw can become moldy

Compost

Compost can be used around any plant.

Advantages

• Easy to spread
• Improves the soil structure
• Adds nutrients to the soil
• Absorbs and holds moisture
• Easy to work into the soil
• Easy to make

Disadvantages

• Contains weed seeds
• Can be hard to find
• Often expensive
• Requires room to make
• Nutrient content unknown

Manure

Manure must be well rotted before being applied to the garden. Green manure has obvious odour and the urea content will burn plants. Well-rotted manure from domestic animals can be used around any plants. Manure can also be used as winter mulch.

Advantages

• Readily available in bulk or bag
• Easy to spread
• Improves the soil structure
• Adds nutrients to the soil
• Absorbs and holds moisture
• Winter mulch can be worked into the soil
• Easy to work into the soil

Disadvantages

• Contains weed seeds
• Not always constant texture
• Nutrient content is often unknown

Leaves

Leaves are often used to cover tender plants during the winter.

Advantages

• Free for the taking
• Do not attract rodents or pests
• Can be composted in the spring
• Light and easy to move

Disadvantages

• Light and blow away
• Take nitrogen away from plants during the growing season if not thoroughly rotted
• Bulky

Grass clippings

Grass clippings can be used around most plants and as winter mulch.

Advantages

• Inexpensive/free
• Constant supply
• Will quickly form a mat, blocking out the most obnoxious weeds

Disadvantages

• Care needs to be taken not to use sprayed grass
• Not pleasing to the eye
• Attracts pests

Rocks

Rocks or gravel are used extensively as ground cover in commercial landscaping. Homeowners use it to mulch tree and shrub beds.

Advantages

• Attractive
• Comes in several different colours and sizes
• Never breaks down

Disadvantages

• Traps the heat
• Heavy to work with
• Hard to weed
• Needs to be placed on a barrier or it will sink in the soil
• Expensive
• Does not condition the soil

Biodegradable Weed Barrier

This is a commercial product made primarily from corn products. It should not be confused with a plastic product that breaks into small plastic particles that stay in the soil forever. Biodegradable Weed Barrier comes in rolls and can be easily used in vegetable and annual beds. It only lasts a season, which makes it impractical for perennials, trees and shrubs.

Advantages

• A great weed barrier
• Warms the soil
• Can be dug into the soil or a compost pile

Disadvantages

• Does not stand up to traffic
• Must be stretched smooth or it breaks down quickly
• Must be replaced each spring
• Must be ordered from specialty houses
• Does not let air or water penetrate the surface
• Does not add nutrients to the soil

Paper

Paper is usually used in combination with another material.

Advantages

• Usually free for the taking
• Makes an excellent weed barrier

Disadvantages

• Not pleasing to the eye
• Can become messy if not covered by another material
• Tears easily when wet
• Needs to be used in combination with another mulch
• Chemicals in the ink can be a problem
• Must be wet when applied

Landscape fabric

Quality differs between types and brands of landscape fabric. It is important to purchase one with a tight weave that will not let the light penetrate. Even so, all perennial weeds must be eliminated before installing the fabric. Landscape fabric is used as a barrier under rock or wood chips.

Advantages

• Allows air and water to penetrate.
• Works as a weed barrier
• Readily available
• Lasts for many years
• Pleasing to look at when used with chips or rock

Disadvantages

• Can be expensive
• Quality varies with brand
• Will not block perennial weeds
• Breaks down quickly when exposed to the sun

Plastic

Plastic is often used under rock or wood chips to work as a weed barrier. Thin plastic can be used to cover the ground to warm up the soil in the spring and to protect tender plants from spring frosts. Thicker plastic can be used between the rows in the garden or orchard to keep weeding and tilling to a minimum.

Advantages

• Heats the ground
• Keeps in moisture
• Effective barrier against weeds
• Fairly economical
• Readily available

Disadvantages

• Needs to be covered by another material or it rots in the sun
• Water and air can not penetrate the surface
• Does not add nutrients to the soil
• Small pieces will become part of the soil

Carpet – jute-backed

Recycled jute-backed carpet works as an effective weed barrier. It is best used between rows in a vegetable garden or orchard.

Advantages

• Allows water and air to penetrate
• Often free for the taking
• Will last more than one season

Disadvantages

• Not always pleasing to the eye
• Chemicals can leach out of the carpet
• Bulky to move and store