Guide to soil improvement

The most important part of gardening is building and maintaining healthy soil. Rarely, native soil is ideal for the plants we want to grow in our landscapes and gardens, so we add things to improve them. Soil improvements can turn poor soil into a productive garden by improving drainage, water retention, aeration, nutrient buffering ability, beneficial microbial levels, and more.

Soil improvers include a variety of organic and inorganic materials such as compost, mulch, perlite, and sand. Each species offers a unique set of benefits that improve the structure, biology, or chemistry of the soil, which in turn results in a better growing environment for plants. Know in advance how and why to use easy-to-find soil improvers.

Wood chips

Wood chips come from tree trunks, twigs, and branches that are about 12 inches and smaller in diameter. They should be allowed to age before using in the garden. While the material is dormant for at least 6 months, beneficial organisms colonize it and slowly begin to turn it into soil. Earthworms thrive in gardens with wood chips.

Mulch the soil surface around established plants with wood chips in a 2 to 4 inch layer. Most tree cutting and moving companies often give you a free truck load of wood chips.

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Cut grass and leaves

Use these two lawn waste independently or together. For passive soil improvement, use a lawnmower with a mulch deck to mow the lawn. A thin layer of mulched leaves will restore nutrients to the soil and help save water. Mulched leaves increase the carbon content of the soil and improve the soil for earthworms and other beneficial soil dwellers.

To improve a garden bed, mix one part fresh grass clippings with two parts dry, shredded leaves. Apply the mixture to an empty garden bed in a 6-inch layer to improve the soil over the winter.

Bone meal

Bone meal is a traditional organic fertilizer that increases the phosphorus content of the soil. It is available wherever gardening supplies are sold. Before adding bone meal and other fertilizers, it is best to do a soil test to make sure the soil needs this nutrient. Plants use phosphorus to grow roots, flowers, and fruits. Apply bone meal at the beginning of the growing season to feed the plants for a full season.


Biosolids are organic solids from sewage treatment plants. The material is stabilized through anaerobic digestion and composting to eliminate potentially dangerous pathogens and then packaged as commercial fertilizer. These fertilizers have been used in American agriculture, golf courses, and home gardens for more than a century. In addition to the added nutrients, this material increases the levels of beneficial microbes and organic matter in the soil.

Wood ash

If you are burning firewood in a wood stove or fireplace, the garden is a good place to dispose of the ashes. Wood ash can replace lime to increase the pH of the soil. It also increases potassium levels and many of the trace elements plants need.

A little goes a long way, and adding too much at once can damage the floor. Sprinkle wood ash fertilizer over the garden at about 20 pounds (5 gallons) per 1,000 square feet. Or, sprinkle something on the compost heap every time you add new trash.

Soil improver wood ash


Whether you make it yourself or buy it from a store, compost is one of the most famous and useful soil improvers. Businesses and home gardeners make compost from virtually any organic material – from weeds and vegetable scraps to cardboard and sewage sludge – so the quality, texture, and nutritional content vary significantly.

Compost in the soil before planting. Add it to the soil surface as mulch after planting or brew it into compost tea for foliar feeding.

Soil improvement compost

Paper carton

Given the massive increase in online orders, it is good to know that there is a way to use some of this packaging material in the garden. Paper or cardboard can serve as a biodegradable weed barrier by simply placing them on the garden bed and covering them with 4 to 6 inches of wood chips or other organic material. You can also shred paper or cardboard to add to the compost heap as a carbon source.

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