Mulch is one of the greatest aids that a gardener can use. It may just be a layer of something put on the surface of the soil, but oh how that layer can improve what you grow! And who wouldn’t want to reduce some garden tasks – like weeding and watering for starters.

BY JOYCE RUSSELL

This article was featured in our Home & Garden 2026 supplement – you can read the full supplement here!

Some types of mulch provide several benefits for the garden and gardener, others only one, but the trick is to start mulching and use what you can.

Put different types of mulch in layers on top of each other if you want.

You will soon become a devoted fan of using any available mulch in your garden.

Five Reasons to Mulch

To feed the soil. A good organic mulch, like compost, will break down and release nutrients into the soil.

This is particularly good for poor soils, greedy plants, and for ones that have established roots that would suffer from disturbance.

To reduce weed growth.

A thick layer of mulch will supress annual weeds and will slow the growth of many perennial problem weeds.

Weeds that do grow through a mulch are usually easier to pull, or dig out, when their roots are growing in loose mulch material.

A mulched bed needs way less weeding than an un-mulched one.

To retain moisture. Soil can dry out fast in hot weather and water supplies can be restricted if there’s a drought.

Trap moisture in a damp soil by covering with a thick layer of mulch and you won’t have to water as often.

To improve soil structure. Worms pull organic material from a mulch layer down into the soil.

And if you turn the bed over, later in the year, you are adding in bulk material to loosen a heavy soil.

Alternatively you can try no-dig methods and just keep adding layers of mulch without digging the soil over.

Last but not least – some mulches look nice.

Mulch can provide a consistent, attractive, weed-free layer to give a clean, neat look to beds.

Other mulches aren’t so good to look at, but they serve other purposes.

What to use – Some things you can get for free

Grass Clippings – Spread a 3cm layer of clippings between rows of vegetables each time you mow. They are particularly good between rows of peas and beans and can be used to earth up around potatoes. It’s best not to use clippings that are full of seeds.

Photo: Ben Russell

Compost – Garden compost can contain weed seeds if it hasn’t heated enough. Top with a layer of a light-blocking mulch to keep weeds down. Bought compost is sterilised and weed free.

Manure – Should be well-rotted so it doesn’t harm plants. Use around nitrogen-greedy plants like blackcurrants and leafy green vegetables.

Cardboard – Weight down sheets so they don’t blow away. Cardboard will rot over a few months exposure to rain.

Recycled black plastic – Is perfect for covering over other layers of mulch like manure or compost. Cut holes through in order to plant onions. The bed will stay damp underneath, much longer than uncovered ground, even in a hot summer.

Leaves – Can be piled on empty beds in the autumn. They will slowly break down to improve soil structure and, in the meantime, they help to shed water from the soil.

Stones – Look pretty in pots and containers. Water can run through, but evaporation is reduced and cats and birds can’t scratch in the compost.

Wood shavings/sawdust – Used fresh these can rob nitrogen from soil. Use them to cover paths over soil between beds.

Pine needles – An acid mulch that can be used to deter slugs if piled around vulnerable plants.

Seaweed – An excellent feed for any soil. Lots of gaps for weeds to grow through so pile on thickly, or add a layer of a different mulch to reduce the problem.

What to use –  Some things you can buy

Cocoa shell/Coir – Buy in bags to use as clean, attractive, decorative mulches. Good on flower beds. 

Bark chip – Makes an excellent path-covering although it will have to be topped up each year.

Compost – Provides nutrients for a couple of months. It looks clean and attractive in flower beds and will help grow healthy blooms. Buying bags of compost can be an expensive way to cover large beds – use as a topping over garden compost to reduce cost and keep weeds down.

Manure – can be bought by the bag or the trailer load. Leave it in a covered pile to break down if it is fresh. Gives an excellent nutrient boost to any poor soil.

A word of warning: Slugs can hide under mulch layers. You can use organic-approved pellets or only mulch around larger plants where slug damage is less of a problem.