Do you have mulch time on your hands this autumn?

Autumn is the perfect time to add some good quality mulch to your garden. Have you ever asked the question why we should mulch?

Why mulching is good

Mulching is good for many reasons. Mulch is a thin layer of organic or inorganic material that is placed on top of garden soil, around trees, bushes and surrounding plants. It can also be used as a surface for walkways and pathways, or as a substitute for turf.

It improves the soil condition around plants, reduces weeds, increases soil fertility, helps moisture retention and during winter can protect the roots of the plant from damaging frosts. Using the right mulch for your plants and trees can help eliminate the need for chemical pesticides and fertilisers which is great for your garden’s biodiversity.

A layer of mulch acts like a ‘lid’ that allows water into the soil but helps to minimise its evaporation. It also adds organic matter to the soil which breaks down to form humus, which can be thought of as the ‘life-force’ of the soil. Essentially, it is the end-product of the break-down of organic matter and it provides the ideal habitat and food source for many soil micro-organisms.

Which mulch do I need?

There are many different types to choose from so it is important that you choose the right mulch for your garden area.

1. Non-biodegradable Mulch

Inorganic mulch is mulch that doesn’t break down over time, such as stones, pebbles and slates. It can’t be used as a fertiliser but is usually superior at stopping the weeds as long as it is laid at a suitable depth.

Inorganic mulches are used to protect the soil around the plant and can also have an aesthetic edge to them. The benefits include locking in water to the soil, keeping weeds at bay and unlike some organic mulches it won’t wash away which is perfect if you are planting on a slope. It is also great for walkways.

2. Biodegradable or Organic Mulch

Organic mulches break down over time, such as bark or wood chips. As it decomposes, it helps the soil by adding more nutrients and by improving the overall structure of the soil, which improves drainage. Over time the mulch will degrade and replenish the soil’s nutrients. Organic material also promotes biodiversity and encourages insects such as worms and spiders, which will keep pests at bay while further enriching the quality of your soil.

Be aware that organic mulch needs to be replenished, and as a rough guide this should be done once every two to three years. Below you will find the different types of mulch and which one would be most useful to you.

Different types of organic mulch

Bark and wood chip

This organic mulch is attractive but also helps improve your soil’s nutrients and structure as it rots down. It allows water to flow through it without binding throughout the year and really is fantastic for pretty much all plants and circumstances. The only issue with it is that it is difficult to move or work around and so is best for around trees where you won’t be doing any more planting. Bark and wood-chippings will last you through the year and maybe even two depending on the grade, see how far it has broken down and replace if necessary.

Compost or soil improver

There are two main reasons why compost can make a great mulch:

  1. It is packed full of nutrients ready to leach down into the soil and
  2. It is something you can make yourself free of charge.

Additionally, it helps with keeping the soil moist and fending off weeds. One thing to look out for however is that no weeds have made their way into the compost as these will simply sprout up from the compost and steal your plants nutrients. PAS 100 compliant soil improver guarantees very good quality and it is high in nutrients.


When it comes to roses and other phosphate hungry plants nothing compares to some well-rotted manure. Like a compost that has gone through a far more strenuous decomposition process it is packed full of nutrients and its dense texture protects the roots and keeps the water locked in. It is also a really great mulch for trees and shrubs although to prevent waterlogging it may be worth mixing with some sand to allow for greater drainage

Leaf mulch

Leaf mulch or leaf mould is formed from decaying leaves and produces an invaluable soil conditioner. The best quality leaf mould is produced from the leaves of oak, beech or hornbeam, however, all types of leaves and needles can be used to make soil improver. Some thick leaves may need shredding before adding to the leaf mould pile. Gather the leaves, put them in a large bag such as a bin liner, create some small holes in the bottom and come next year you’ll have some quality (free) soil improver ready to be used.

When and how to mulch

The best time to apply a mulch is in autumn, as you come into bare-root season, and spring. You will need to apply the mulch when the ground is relatively warm and moist and avoid periods when it is frozen or waterlogged. When the ground is good to dig and plant, it will be good to mulch!

Mulch helps prevent weeds, but it doesn’t stop weeds growing entirely. You’ll still need to pick over your flower beds a couple of times a year, and it may be worth raking the mulch up a bit at the same time to maintain its appearance. To be totally effective, the applied mulch needs to be around 5cm (2in) thick, but mustn’t make direct contact with the plants.

Our mulch

Creating the perfect formula for great mulch takes time and at Earth Supply we’ve done all the hard work for you. Have a look at our mulch and wood chip range:

Leave a Comment