Why I mulch

Published on May 26th 2019
A wheelbarrow in front of a pile of mulch
Being a gardener, I'm at my busiest in spring, with post-winter tidy ups, planting this year's crops, cutting grass and weeding out everything growing in the wrong place. Keeping on top of my own allotment is a struggle, and the weeds take every opportunity to steal a march, producing seeds to increase my workload for the next 7 years.
My Grandmother's approach was to plant so many things in the border, the weeds didn't have a chance to move in, but I prefer to mulch.
A gloved pair of hands holding shredded garden waste

Stopping weeds.

Applying a thick layer of mulch helps to prevent weed seeds from germinating. The lack of oxygen as well as fighting their way up through the equivalent of a Tower block of duvets soon exhausts the seeds reserves. On the downside, it has the same effect on Spring bulbs, sometimes preventing them from growing. I have to remember not to mulch the daffodil and tulip patches, waiting until the summer before mulching there.
There are also other benefits to mulching.


My allotment is on the site of an old brickworks. Some areas are very stony and free draining while parts still have clay very close to the surface. The mulch helps to deal with both. The impact of raindrops on soil creates a surface crust which can lead to further rainfall running off down the slope to my allotment neighbours instead of being absorbed into my waiting patch.
A good thick mulch will slow down the passage of water and reduce impaction, helping to prevent moisture from evaporating too quickly. It will hold onto a percentage of the water, all of which reduces how frequently I have to water, but not the quantity, the water has to further go through to reach the plant's roots.
Mulch between plants on a garden border
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Frost protection.

I don't plant much on my plot that needs winter protection, preferring to grow hardy perennial flowers or annual vegetable crops, but I do have several fruit bushes and a Fig whose roots benefit from not being lifted up and down by the effects of frost on soil, known as Frost Heave.

Soil structure

If you've used manure, wood chip, bark, hay, straw, compost, leaf mould or grass clippings the worm population will do the hard work of incorporating the decaying matter into the soil with the added benefit of opening up the structure. This makes it easier to dig for planting or harvesting root crops.
Potato plants growing up through straw mulch


Biodegradable materials can also provide nutrients to the soil. Although I create my own compost, I never produce enough and always have to bring something into finish covering the beds. This year I found a local source of well-rotted horse manure, but a recent conversation with a volunteer at Shumei Natural Agriculture has made think about dropping the animal fertilisers in future.

When to apply it?

The books say to apply it in mid to late spring and autumn when the soil is moist and warm, trapping those beneficial conditions beneath a layer between 5 and 8cm deep. I have to admit I do most of my mulching in winter because it's when I have the time to do it. It takes a little longer for the worms to start working their way through, but they do eventually. If you don't have enough, don't spread the mulch thin as it won't provide the benefits you are after. Instead, mulch where you can and prioritise the other areas next year.
A close up of pebbles being used as mulch

Decorative mulches

I have several containers where I've used non-biodegradable mulches purely because they're lovely to look at when I'm sat in the garden. In particular, my Acer has a layer of shells collected with my little one during our seaside holidays, which bring back lovely memories every time I'm watering. But you can use all sorts of things, such as slate, shingle, pebbles, glass beads or stone chippings, the list is extensive.


Make sure the mulch does not come into contact with the stems of trees or specimen shrubs as it can cause them to soften, making them vulnerable to diseases.


As with most things, there are a few disadvantages to using mulches. They provide slugs and snails with a place to survive, and bad quality mulch can introduce perennial weeds. I mulch my veg beds every year as it gets incorporated into the soil throughout the season as I plant and crop.
My fruit bush patch doesn't have this and mulches can build up into hard layers that prevent water and feed from getting to the roots. I wait until it has broken down completely before putting on a fresh layer.
Pink gardening gloves, laying mulch over a young tree

My next mulch

Have you heard of Strulch? I hadn't until this week. It's a lightweight, organic garden mulch made from wheat straw that the manufacturers say will last two years and can be used throughout the garden. I have to admit it piqued my interest as an organic material that won't breakdown too quickly, and now is the perfect time for me to mulch around my strawberries. A trip to the garden centre is today's plan.
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