To put it simply, a mulch is a layer of material that you put around your garden plants, on the very top of the soil. This can range from homemade compost to leaf mold, gravel, and more, and all have their benefits.  To get the most out of your mulching, there are some handy pointers to bear in mind, including when and how to do it. We’ve put together everything you need to know to get started, with plenty of tips from the experts. 

What are the different types of garden mulch?

Broadly, there are two different types of mulch: biodegradable and non-biodegradable.  Biodegradable (otherwise called organic) mulches decompose over time. Aaron Green, Founder of Essential Home And Garden (opens in new tab), lists compost, grass clippings, shredded leaves, and bark as examples. It’s easy to spread, and has the benefit of improving the soil as it breaks down. ‘However, this type of mulch does need to be replaced every few years,’ he says.

What are the benefits of mulching?

Mulching is beneficial for more reasons than one. Suppressing weeds: One of the top benefits of mulching your plants is that it slows down the need to get rid of weeds, as it blocks out the sunlight they need to grow. As Deborah Niemann, the owner of Thrifty Homesteader (opens in new tab) says, ‘Even though some people talk about weeding as if it’s wonderful zen time, it gets old fast! I absolutely love mulch because it reduces weeding time down to almost zero.’ Retaining moisture: Mulching keeps water from evaporating from the soil too quickly, which means you won’t need to water plants as often, Deborah says. This is particularly useful if you expect periods of drought. ‘When you can’t rely on Mother Nature to water your garden, you suddenly realize how much water it really needs. So, preventing water from evaporating becomes really important.’ Improving your soil: As mentioned, biodegradable mulches break down. Some types, particularly leaf mold and homemade compost, will improve the nutrient content of your garden soil as they do so. They will also benefit the structure of the soil, by improving aeration and drainage. Providing winter protection: Think of mulch as a blanket that protects your plants against inclement winter weather. ‘The most important task to perform going into the winter is to have the plants well mulched with compost, wood chips, salt hay or a similar organic biodegradable material,’ says Chris Kemp, an arborist, plant healthcare specialist, and Manager of the Plant Healthcare and Treecare divisions at Piscataqua Landscaping & Tree Service (opens in new tab) in Eliot, Maine. ‘This layer will protect the roots of your plants during cold snaps and dry spells by moderating soil temperatures and keeping moisture around the roots,’ he says. If you grow dahlias and live somewhere with relatively mild winters, a layer of protective mulch can substitute having to lift and store the tubers until warmer weather arrives. Upping aesthetic appeal: Last, but not least, mulching can improve the overall look of your borders. Bark chippings and gravel can give them a much more orderly appearance in contrast to bare soil, for instance.

How to mulch

Mulching is a must for a low-maintenance border – simply cover the entire bed. But, you can also apply mulch around individual plants. If the latter, aim to extend the mulch to match the diameter of the plant. Try to remove all weeds before you apply it, as well as watering the area if it’s dry: that way, it will lock in the moisture. ‘Keep it off the crown as it may collect moisture when it rains, which can cause the crown to rot,’ says John Negus, a gardening expert from Amateur Gardening magazine. If you’re using landscaping fabric over a flower bed, you don’t necessarily need to remove weeds from the soil first, as it will quickly smother them. Simply cut crosses in the fabric to plant through. You can then top the fabric with mulch for a more aesthetically-pleasing finish.

How thick should a layer of mulch be?

‘When laying down mulch [aside from landscaping fabric], put down a layer two-to-three inches thick. Any thinner and you won’t be getting the full benefits of the mulch, but any thicker and it could play host to harmful pests,’ says Aaron Green.

When should you mulch your borders?

You can mulch at any time of year, but most gardeners treat it as a late spring or early fall job, or both, depending on whether it needs a top-up. Mulching at the beginning of the gardening season can suffocate the baby weeds before they have a chance, says Deborah. Mulch applied in fall will offer that all-important winter protection. Apply it before the soil hardens with frost, advises John Negus. ‘Additionally, worms, which are still active now as the soil has retained some warmth from the summer sun, will integrate the mulch into the soil and improve its beneficial humus reserves,’ he adds.

Avoiding problems with mulching

Watch out for pests: Mulch can sometimes attract pests, particularly slugs and snails. Be vigilant, and if you spot them, use a natural slug control method, such as a beer trap.Leave a gap around the stems of woody plants: If you don’t, the mulch can cause them to weaken and rot.Keep it tidy: ‘A freshly mulched bed or border is irresistible to birds. It’s a soft area for them to poke around in and discover juicy grubs and other delicious food,’ says John. ‘Apart from raking the mulch back onto the garden, all you can do is erect a mini fence around the site so that the material stays on the soil.’ Luckily, there are lots of stylish garden edging ideas to choose from.