The importance of mulch

There is one job I rate as more important than any other in the garden; mulching. The application of a thick layer of organic matter to your beds will have multiple benefits and the garden will reap the benefits for years to come. 

At the moment, the leaves are still falling and the trees and shrubs are applying a thick layer of their own organic matter to the beds, but this will soon slow down. Now that all my bulbs have been planted, and the leaves will soon be cleared (where necessary) I will spend the next few weeks giving all the beds a dressing of composted bark mulch. This has many benefits for the soil. The thick layer of organic matter will act as a blanket, retaining warmth and keeping its biological processes at work long into the winter. It will provide protection from the erosion and leaching caused by winter storms. The blanket effect will also help to reduce the number of weed seedlings that appear as the soil warms again in the spring. Over the next 12 months it will gradually be incorporated into the soil by worms. Mulches generally have little nutrient content to add to the soil, but they will slowly improve the structure of the soil, making it less prone to compaction, able to retain more moisture, and making the ideal home for an even more diverse selection of beneficial fungi and bacteria.

It doesn’t just have practical benefits. After the storms of autumn have taken their toll on the borders, this is the ideal opportunity to dress the garden. The recent frosts have meant tender annuals and soft-stemmed perennials have melted into an indistinguishable sludge leaving just the sturdier plants with their handsome winter outlines and attractive seed heads. Filling in the gaps in the border with a protective coating of mulch provides a uniform background to display all those structural plants to their absolute best.  

There is a huge choice of substrates that can be used for mulching. My personal favourite is composted bark. It is light, easy to spread evenly, conditions the soil beautifully and is relatively inert, so you wont get a huge bloom of weed seedlings on top of it. On the veg patch I like to use the well-rotted compost from the bottom of our enormous heap. It doesn’t contain as much nutrients as animal manure, but it does provide some nutrition, and will quickly bulk up the soil. In the hot, Mediterranean garden we apply a layer of limestone chippings each spring, which don’t provide much in the way of nutrients for the soil, but are excellent for improving drainage and reflecting heat, meaning it is consistently the warmest part of the garden.

On amenity plantings, coarse bark chippings are often used as they breakdown much slower and will protect the soil from wear and compaction for a longer period before they need to be replaced. Mushroom compost is a popular option for veg growers. This is an animal manure which has been processed, then used for growing mushrooms. It is high in nutrients and excellent for the veg patch. I have also previously used recycled green waste on my allotment. You need a sharp eye to watch out for any household items which may have made it through the composting process but, apart from the teaspoons, it certainly helped to improve the soil structure. I have also used strulch, a mineralised composted straw. It takes a while to break down, and the minerals can affect the nutrient balance of the soil if used over a long period, but it does give a very even appearance, and is very light to move and spread.

Recently, I have become interested in the idea of using plants as ‘living mulches’. The use of green manures has gained momentum in recent years. In the winter, rather than leaving soils bare, or covering in manure, a secondary crop is sown, grown, then dug into the soil just prior to the next planting season. Legumes like beans, phacelia or clover are popular for increasing nitrogen, and mustard has become popular to act as a ‘soil sterilant’, reducing the incidence of pests and diseases. The climax of this idea must be the techniques advocated by Japanese horticultural researcher Masanobu Fukuoka in his book “The One-Straw Revolution”. In the book he describes his natural system of farming. Cereal crops such as rice, root crops like radish and vegetables such as squashes, are sown in mixed fields using clay pellets, through a living mulch layer of legumes like clover that feed the crop as it grows. When the field is harvested the waste straw is left in the field to compost where it grew, and the next crops are sown directly through it. The system tries to mimic natural systems as closely as possible and it was claimed that his farm achieved yields comparable to his neighbours with no inputs of fertiliser or any use of pesticides. As yet, I haven’t yet been able to initiate a ‘one-straw revolution’ system on my allotment beds, and I’m not entirely sure the allotment committee would look benevolently on such an experiment, but over the next few years I am hoping to see how I can use the principles of this system to inform my own growing, and hopefully find a way to make my plot as self-sustaining as possible.


Author: jlrobbins

I grow plants

3 thoughts on “The importance of mulch”

  1. I’m accidentally using forget me nots as a living mulch on my veg plot this year. Just hope I can dig them out before they flower. Pretty as they are- they are so invasive. Where do you get your bark mulch from? All the best. Karen

    Liked by 1 person

    1. The forget me nots certainly work at smothering out any weeds in the borders, and are so pretty with tulips in the spring. I get my composted bark from Thompsons of crews hill. I need about 25m2 to do all the beds so it is cheapest to get it loose.

      Liked by 1 person

      1. Thanks James. It’s interesting what we find out by making mistakes. It’s working amazingly well at protecting the soil. I’m now sourcing local supplies of bark mulch. Thanks for the information.

        Liked by 1 person

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