Mulching is the simplest way to protect, feed and improve your garden over winter, ready for stronger growth next spring. Ecologist and gardener Becky Searle shares why mulching matters and how to pick the right mulch for your soil:
Mulching Matters
The curtain is closing on another growing season, and as we reflect on the year gone by, we are also looking towards the year ahead. We all want to feel as though we are doing something positive for our gardens and allotments. They give us so much, and we want to love them in return.
One of the best things you can do for your gardens this autumn is to look after the soil. As we bring home armfuls of beautiful flowers, or baskets full of tasty fruits and vegetables, we are removing organic matter from our plots. The plants create this organic matter, and when it is not, at least in part, returned to the soil, the soil is deficit. So, if you want to show your soil some love this autumn, I recommend mulching.
What is mulching?
Mulching is the process of laying organic matter, usually in the form of compost or well-rotted manure on the surface of the ground. It is then gradually incorporated into the soil by the organisms that live within, as they come to the surface to feed. These creatures then distribute the organic matter through the layers of the soil and form organic glues. These glues, made primarily by bacteria and fungi help to bind the particles of sand, silt and clay within our soil, pulling them together into aggregates, and opening spaces called pores.
Aggregates act like tiny subterranean sponges, clinging onto water, while pores allow water and air to filter through the soil.
When we dig in the organic matter to our soil, we break up fungal hyphae, disturb the soil ecosystem, and dissolve the glues holding together soil particles.
So, what’s the catch? Can it really be as simple as adding organic matter to your beds and then walking away?
Well actually, it is that simple. Doing this will help to suppress weed growth, feed your plants, increase the water holding capacity of your soil and aerate it, without you needing to do anything else. It’s the ultimate gardening “hack”. Of course, like everything in nature, it takes time. One cannot expect an army of microscopic organisms to build good soil structure overnight. This therefore makes it difficult to see the difference that your making, as the change is slow and subtle.
So, to make sure you’re doing it right, here are a few tips from me, author of Grow a New Garden, on how to mulch in the right way for your garden. Before we begin, you will need to understand what soil type you have:
Simple soil test
Go into your garden or allotment and dig down a few inches. Take a handful of soil and hold it in your hand. See if you can shape it into a rough ball. If you cannot shape it because it falls apart too easily, you likely have sand or silt soil. Sandy soil will feel grainy, where silt soil feels smooth and soft. If you can shape it into a ball, now take your thumb and forefinger and squeeze the ball. If it crumbles when pinched, you likely have a loamy soil, but if it just indents, or splits rather than crumbling, you have clay. Other clues are:
- Sandy soil: well-drained, easy to dig, often light in colour.
- Silt soil: very light and dusty, feels soft to touch, water can sometime run straight off the surface rather than soaking in.
- Clay soil: sticky and slippery when wet and hard, sometime cracking when dry.
- Loam: often a dark chocolatey colour, feels crumbly and is easy to dig.
We should note that all of these soil types exist in a spectrum, and will consist of sand, silt, clay and organic matter, in differing quantities. Your soil may look like something in between two or more of these soil types.
Choosing your mulch
When you know what kind of soil you have you can choose the right mulch for your garden. I always choose Dalefoot Composts as they are organic, high-quality products that help to support conservation work and sustainable farming in the Lakeland fells. I have been using Dalefoot for many years and always find it excellent to work with. It doesn’t contain slow-release nutrients, but rather a suite of naturally occurring nutrients that help to feed your plants, and support the insect and microbial communities in your soil.
Mulching on sandy or silt soil
Sandy and silt-based soils are well-drained, and don’t hold onto water very well. As water can drain through them quickly, nutrients can be washed away, meaning that sandy and silt soils are often less nutrient-rich than clay or loam. So, when you choose your mulch you will want to choose one that is rich in nutrients, like Dalefoot’s Wool Compost Double Strength, with added nutrients from comfrey. This is a soil improver, and while not suitable for young seedlings, if applied in autumn can help to bolster the health of your soil before the new season begins. I would recommend covering the soil too, either with a cover crop or green manure, or with cloches to help minimise nutrient loss. If you want to be able to plant straight into your mulch, try using the Wool Compost for Vegetables and Salads, as this works very well as a mulch and isn’t too strong for seedlings when used as a mulch.
As sand and silt soils are so free-draining they will likely need a thick layer of mulch if you want to reduce the amount of watering needed. After a few years of consistent mulching, you should be left with much-improved soil that holds water and feeds your plants effectively.
Mulching on clay soil
As clay soils can hold a lot of nutrients, but lack drainage, the aim of your mulching should be to improve the structure of the soil. This will help it hold water in the summer and not dry and crack, and help it not get slimy, sticky and waterlogged in winter. However, to improve the structure of clay soil, it is important to choose a mulch that contains lignin. Lignin is a protein found in wood and bracken. It’s very hard and breaks down slowly, and as it does so it forms glues that help to bind soil particles. As such, lignin is excellent at adding structure to clay soils. That’s why for my clay soil I choose Dalefoot’s Lakeland Gold compost, which is made with bracken from the Lakeland fells, adding lots of lignin and feeding my soils.
Mulching loamy soil
Loamy soils don’t need a lot of mulch as, by their very nature they are rich in organic matter already. However, it is important to treat them with care, minimising disturbance, and putting back what you take. If you are harvesting from loam soils, be sure to apply a layer of mulch to replenish their organic matter content, but you will not need to do this as much or as often as you would with soils containing less organic matter.
Other ways to improve your soil
If you want other ways to improve your soil this winter, why not consider planting cover crops. Field beans are an excellent choice of cover crop that will help to add nitrogen to your soil, and if you let them go to seed, will also provide you with a crop. They make large plants that add bulk to your compost pile, and they are easy to remove once you are ready to use the space. You simply need to snap or cut them off at ground level. Other cover crops include Daikon Radish that can help to decompact heavy soils. Mustard, rocket, and phacelia are also easy to work with in a no dig system, and do not require you to dig them in, rather remove the top part of the plant, leaving the root in the soil, and use the tops to add to the compost. In the summer, sunflowers also act to decompact heavy soils with their deep roots, giving you the perfect excuse to grow more of them!
So, if you want to give back to your garden this winter, give it some mulch and make sure it’s the right sort for your soil type. And if possible, try growing some green manures and cover crops as well, your garden will thank you next year!
About the author:
Becky Searle is an ecologist and gardener best known for her Instagram account @sow_much_more. Her new book Grow a New Garden takes an ecological approach to planning, designing and creating a garden from scratch, or transforming your existing space. With a whole chapter on soil, and lots of information on balancing your garden ecosystem, this book is a mine of information for new and experienced gardeners alike.