Mulch in your Garden: Benefits and what to use
13 January

Mulch in your Garden: Benefits and what to use

By Cornelia Holten
Published: 13th January 2020

Our aim is to have our productive garden beds in the herb and vegetable gardens covered with mulch at all times, summer and winter, 12 months of the year. Here is why.

In summer mulch retains moisture in the soil and prevents it from drying out. Mulch is dead organic matter and provides a food source for bacteria and fungi, who kick start nutrient cycling. Once those get eaten by protozoa, earth worms and nematodes (bacterial and fungal feeding ones) the nutrients are released right where they are needed in the root zone for the plant to take up.
It also helps to control and suppress weeds in freshly planted garden beds and in spring, autumn and winter it prevents the heavy rain to damage the soil structure, which can result in a hard pan.
The only negative aspect that I can see is that mulch provides a breeding ground for slugs and snails, which can damage freshly planted seedlings. We keep Indian Runner ducks for that purpose (and they lay yummy eggs!) and we let them free range in the garden over the winter period and whenever needed.

Image above: Indian runner ducks in the herb garden working their way through the mulch to find slugs and their eggs.

Our garden has grown immensely over the past 6 years. We started off using bales of bought pea straw and linseeds straw, but certified organic options are not easy to find and are expensive. Over the last 3 years we have tried many options and I want to show what you can use to cover your soil.

Option 1: Plant residue from the crop that got harvested

Here we have taken down our pea frame as they have stopped producing peas. The empty bed was fed with one wheelbarrow load of compost and the pea plants were layered on top. No digging was done to not disrupt the soil food web, only feeding to boost fertility. To plant the next crop, we will simply make a hole in the mulch and plant the seedlings into the compost.

Option 2: Seaweed


Whenever we see seaweed washed up on the beach we take what we can (there is always bags and buckets in our truck for that purpose). After a storm we take our trailer. Seaweed is rich in nutrients and trace elements crucial for plant growth and nutrition. Our last soil test has indicated low sodium levels, therefore we do not wash the salt water off the seaweed, we put it straight on. If sodium levels are high in your soil, you might have to rinse it before using it.

Option 3: Woodchips

Pretty much any woodchips are fine. The more variety of the wood, the better. Woodchips provide a valuable food source for fungi. Beneficial fungi are generally lacking in our agricultural systems as they dislike fungicides of course and cannot deal with the frequent digging over of soil by tractor or hand. Detrimental fungi are the ones that bounce back faster after disruption and sprays and without competition from the good guys we see fungal diseases like rot, club root and mildew in agricultural settings and home gardens.

Option 4: Autumn leaves

Same applies as for the wood chips, the more variety the better. Leaves from trees with high lignin levels like oak, chestnut and magnolia can take 2-3 years to break down and some contain toxic substances like eucalyptus leaves, that prevents them from breaking down in the first year. Use them sparingly and mix them with poplar, willow, maple and ash leaves, which break down faster.

Option 5: Wild edible and medicinal plants aka weeds

Wild plants, that grow in abundance, make great groundcover and when uprooted they quickly dry in the summer sun to provide a protective mulch layer releasing nutrients right where they have taken them up. We let them grow freely in our garden and value their nutritional and medicinal benefits. They are harvest for meals, juice, smoothies and salads and we uproot them only when they start to take over or smother crops.

Option 6: Grass clippings

Grass clippings need to be spread out thinly so that they don't get hot and topped up frequently. They make great mulch for delicate crops like those freshly germinated carrots. If you get grass clippings from someone else please make sure they are from a spray (herbicide, fungicide, pesticide) free lawn.

Option 7: Comfrey

Comfrey makes fabulous mulch. It has a deep taproot, mining nutrients from the deeper layers of the soil, where your crop's roots might not get to. When cutting it back, the leaves break down and nutrients are released in plant available form. We grow it on the outer edge of the gardens and in the forest garden around fruit trees. It grows fast with lots of leafy growth and can be cut at least 5 times between early summer and late autumn. Above two freshly planted pumpkin seedlings and the mulch still standing tall behind it. Below it has been cut and layered around the seedlings.

Option 8: Hedge trimmings

Hedge trimmings provide mulch in the form of the leaves that fall off when they dry and the stalks provide protection from birds scratching around freshly planted seedlings. We have had great results with this method this year and used hedge trimmings on several occasions instead of bird netting. This works for seedlings that are not food for birds and are only getting damaged by blackbirds scratching around them wanting to get to the worms from the compost that has been applied before the seedlings were planted.

This list is by no means complete, but should give you inspiration that a lot of materials work as mulch and I hope you start looking around your garden now to find just the perfect "waste" material, that is well suited to protect your soil and feed your soil food web.

I hope you got some inspiration for mulch materials and find a way to stop using pea straw.

Did you know that a lot of conventional pea straw gets sprayed with roundup before harvest to make harvest of the peas easier?

Happy Gardening!

About Cornelia Holten

Cornelia Holten

Cornelia is an herbalist and slow food educator with a passion for simple living, DIY, herbs and self-sufficiency. A certificate in Organic Horticulture, the Soil Food Web, an Apprenticeship in Herbal Medicine and living on a farm in Pigeon Bay equip her with a lot of knowledge and experience with growing food and living a healthy life.

She is teaching workshops on sustainable food systems, whole foods, fermentation, primal diets and organic gardening. A thirst for knowledge and a passion for new scientific studies keep her well informed on those topics.