Mulch is generally applied on top of soil rather than mixed in, with a recommended depth of 50 -- 75 mm 5 0 - - 7 5 m m (2–3 inches) for most garden beds to suppress weeds and retain moisture. For improving soil structure, a 50 -- 100 mm 5 0 - - 1 0 0 m m layer of organic mulch can be mixed into the topsoil when rejuvenating beds.
Use the 2-3 inches of mulch recommended because this depth controls weeds and grass, and helps prevent the soil from drying out too quickly. Too little mulch and you get no benefits. Too much and you risk roots growing in the mulch and not the soil, as well as crown rot .
Typically, it would be best to lay mulch at least 40mm deep to achieve decent coverage. Any thinner, and it will look sparse, allowing you to see the ground through it. If you lay down a 40mm thick layer, your 1m3 of mulch would cover 25 square meters.
Too much mulch will suffocate your plants' roots. Just like you, they need air to breathe. Stick to a nice even layer of one to two inches thick.
There are 25 bags (40 litre) of mulch or bark per 1 cubic metre and 40 bags (25 litre) of soil per 1 cubic metre.
The volume of one 20kg bag is around 0.01m3 or 100 bags for 1m3.
Step-by-Step Guide to Preparing Topsoil for a New Lawn
Mulching's disadvantages include attracting pests (slugs, rodents, termites), promoting fungal diseases and root rot if applied too thickly or against stems, hindering water/oxygen penetration (leading to suffocation), potentially depleting soil nitrogen (with fresh wood), overheating soil in summer, and increasing initial costs and labor for large areas, with poor quality or fine mulches sometimes repelling water, say Ozbreed Plants and Real Simple.
Oxygen Starvation
Suffocation of the roots is the most common cause of tree and shrub death from over-mulching. Repeated applications of mulch in areas with high precipitation or high irrigation can contribute to waterlogged conditions.
Organic mulch doesn't just sit on the surface of your soil—it slowly breaks down, feeding the earth with organic matter and nutrients. This process improves soil structure and encourages healthy root development by increasing beneficial microbial activity.
It's almost always cheaper to buy mulch in bulk per unit (cubic yard) than in bags, especially for large jobs, saving significant money and reducing plastic waste, but bagged mulch offers convenience for small projects and easier transport in regular vehicles, with occasional deep sales making bagged mulch competitive with bulk. Bulk is best for bigger areas (think 1+ cubic yard), while bags are better for smaller tasks where convenience outweighs bulk savings, or if you lack a truck for delivery.
A commercial wheelbarrow is 100 litres and will require 10 loads to move 1 cubic metre.
Rake—A bow rake is the best option for spreading mulch because of its shorter, stronger tines. But you can use a handy leaf rake to get the job done as well. Flip it over and use the back side for a smooth mulch job with no bumps. Gloves—For protecting your hands when you're spreading mulch in hard-to-reach places.
When mixed with soil, bark mulch helps to improve the structure of the soil and provides a range of nutrients.
You don't need to remove the old mulch, as it will eventually break down and enrich the soil. Just remember to maintain a thickness of 2-3 inches of mulch to get maximum benefits for your plants. If the old layer is too thick, you can remove some of it to make room for the new layer.
Ideally, you would apply mulch in the spring after the soil has warmed and before weeds have emerged, but you can apply mulch anytime of the year. If you apply before the ground has thawed, it might delay your soil warming in the spring—but if winter is when you have time to apply mulch, then do it in winter.
There are some species that tolerate excessive mulch better than others. Some of the worst effected plants are grassy plants (iris, daylilies, liriope, etc.), Indian Hawthorn, Azaleas and Loropetalum.
Nitrogen excess
Gardeners often use baking soda as a fungicide to treat diseases such as powdery mildew, black spot on roses, and other fungal infections. How to Use: Mix 1 tablespoon of soda with 1 gallon of water, a drop of dish soap, and optionally a tablespoon of vegetable oil.
When mulching around trees and shrubs, don't pack it against the trunks and stems, where the moisture and wood-decaying organisms in most mulches can rot bark. Pay extra attention around the base of trees and shrubs.
While the material itself does not draw termites to the area, mulch spread over three inches deep creates an inviting habitat for the pests. Layers of organic matter trap heat and moisture next to the ground. Termites use this thick mulch as shelter from harsh weather. Some kinds of mulch may even repel termites.
Three key mistakes to avoid in raised bed gardening are using the wrong soil, building beds that are too wide or shallow, and overcrowding plants, which leads to poor drainage, nutrient depletion, and stunted growth, while neglecting proper spacing between beds also hinders access and maintenance. Focus on a quality mix (not just garden soil), keep beds accessible (under 4ft wide/12in deep), and respect plant spacing for a thriving garden.
Dig In, Dig Deep, and Till Your Soil
Start by tilling the soil down 8 to12 inches. You can do this the old-fashioned way with shovel, and a little sweat or cut down on the time and sore muscles by using a garden tiller. Also remember to pull out any rocks, weeds, dirty clumps and debris.
Incorporation. If the silt is not removed, then the best action is to get plants growing as quickly as possible to start the process of turning the silt into soil. Some perennial plants, such as kiwifruit and citrus have low tolerance of waterlogging and anaerobic soils.