Sheet mulching is a no-till method for starting a new garden or reigning in a garden that has been overtaken with weeds. It consists of layering organic materials over cardboard. The cardboard smothers plant matter and weed seeds while simultaneously attracting worms and other soil organisms attracted to the decomposing cardboard and the plant residue underneath it.
First, cut back vegetation in the area to be sheet mulched. Leave as much of the cut plant matter as possible on the ground, but remove weed seed heads and vines. Dig up any woody plants in the area. Next, use a digging fork to aerate the area and put down a healthy application of fertiliser and water in well. Now cover the area with wet pieces of cardboard. To effectively smother weeds, the ends of the cardboard pieces should be overlapped and again water this. Next, layer organic matter on top of the cardboard and again water in well. Organic matter could consist of food scraps, grass clippings, or manure, followed by shredded leaves or straw.
The organic material on top of the cardboard can reach as high as three feet. As it decomposes, the contents of the sheet mulch will shrink in size.
Sheet mulched areas should sit for at least two weeks before planting, and ideally for three months. This will allow the organic matter to decompose so that its nutrients are bioavailable to plants.
If planting immediately create a hole into the organic matter place 2 good handfuls of compost or good soil into the hole and plant your seedling. They will power away and you will be rewarded.
Ways to Improve your soil quality
Many of us inherit gardens and yards that consist of lifeless or hardpan soil unfit for growing edibles. Good quality soil is essential for an abundant garden and reducing the incidence of pests. While there are many ways to improve soil quality for the purpose of growing food, these are the some of the easiest methods that have been successful for me.
Tilth refers to the physical condition of soil–how suitable it is for planting crops. Healthy soil with good tilth will include lots of organic matter. It will be well-aerated and well-drained, but retain enough moisture to feel like a wrung-out sponge.
To revive lifeless soil, we will aim to improve its tilth.
Gardens that need a boost of vitality will benefit from the addition of organic matter
Organic matter has many benefits to soil depending on the specific material used. In general, organic matter will help to improve soil structure, attract beneficial soil organisms, and make nutrients more bioavailable. Organic matter is a great place to start when improving soil quality, simply because it is inexpensive and because most garden soils are lacking in it.
Again, adding organic matter in the autumn (or at the latest two weeks before planting) will be beneficial for starting the spring garden season on a good note.
Some Animal-based Amendments
These are just some examples of the many kinds of amendments that can be found in large quantities for free or very inexpensively. Use a combination of animal- and plant-based amendments whenever possible, but don’t fret over specifics–just use what’s available to you.
Take a couple of years to add a heavy layer of organic material to your garden beds each fall. Use a digging fork each spring to aerate soil and turn in the amendments. After a couple of years, a soil test is a good next step. A soil test will inform you of any lacking nutrients that need to be supplemented through store-bought products. The organic matter and soil organisms that you’ve added can now help break down the store-bought nutrients and make them bioavailable to your crops, ensuring that you get your money’s worth.
After the second year, continue to add organic matter each fall. However, a high volume of organic matter will not be as essential once you are happy with the quality of your soil, unless you are market gardening and require intensive production.
Mulching protects healthy soil tilth by retaining moisture and nutrients. Mulching saves time by reducing the need for weeding, watering, and fertilising.
The practice of mulching will be different depending on the climate. For example, heavier mulches will be beneficial in hot, dry climates where moisture evaporation is high, while lighter mulches will be more appropriate in cool, rainy climates where soil benefits more from the warmth of the sun.
For most gardeners, a heavy mulch in the off season will provide protection against the elements for beneficial soil organisms and reduce soil erosion from heavy rains. For gardens that sustained pest outbreaks, it is best to discard all affected plant material and NOT apply mulch over the winter. While protecting soil organisms is beneficial, providing winter protection for pests is not.
There are many ways to mulch and many types of materials that can be used.
Dynamic Nutrient Accumulators
Dynamic nutrient accumulators are perennial plant species that are often used in permaculture gardens. These accumulators reach into the soil and collect specific nutrients. We can take advantage of these nutrients by chopping these plants back and mulching with them, or planting them around perennial edible crops. This saves us money by reducing the number of soil amendments we need to purchase. Growing them also improves biodiversity.
Some examples of nutrient accumulators are comfrey, many kinds of weeds, black locust, yarrow, and chives.
There are many ways to improve soil quality, but at the heart of it is reducing compaction, amending soil with organic matter, and taking advantage of the off-season.
We know that “traditionally grown” fruits and vegetables we see in supermarkets are both lacking in vitamins and minerals and have added chemicals from fertilisers and pesticides. These toxic additions have fuelled the demand for organic produce but that has not completely addressed the lack of nutrients.
More things to do!
Cover crops can provide organic matter and nutrients, improve drainage and aeration, attract beneficial soil organisms, and act as an overwintering mulch. While cover crops can be grown in rotation with other crops at any time throughout the year, they are most popularly planted in the late summer or early fall, growing over the winter. Many are killed by the winter cold making spring planting easy. Others are turned under before planting.
It is important to choose the right cover crop for the no-till garden because some cover crops are difficult to kill without tilling. I made the mistake of planting winter rye in one of my first years of gardening. Although I used my digging fork to turn it under before planting, it has continued to sprout in that same area of the garden every year since. This is because winter rye is a grass.
Other examples of grass-type cover crops are winter wheat, oats, barley, sorghum, corn, and millet. While beneficial to the soil, I would recommend skipping them if you do not till.
Instead, choose other cover crops, such as legumes like red or sweet clover, alfalfa, hairy vetch, or sweet peas. Alternate legumes every other year with other cover crops such as buckwheat, daikon radish, forage turnip, or calendula, or try mixing a variety of cover crops together.
If cover crops aren’t winter-killed, use a digging fork (or chickens!) to turn them under about three weeks before planting in the spring. Many of these cover crops can be fed to livestock. Daikon radishes–if not winter-killed–can be harvested for human consumption.