Give Your Garden a Boost with This Guide to Soil Amendments

Show your garden some love with these easy-to-use soil builders.

By Mark Wolfe | Published Jun 23, 2021 2:42 PM

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soil amendments

The most important part of gardening is building up and managing healthy soil. Rarely is native soil ideal for the plants we want to grow in our landscapes and gardens, so we add things to improve it. Soil amendments can convert poor soil into soil promoting a productive garden by improving drainage, water-holding capacity, aeration, nutrient-buffering ability, beneficial microbe levels, and more.

Soil amendments include a huge variety of organic and inorganic materials such as compost, mulch, perlite, and sand. Each kind offers a unique range of benefits that improve the structure, biology, or chemistry of the soil, which in turn leads to a better growing environment for plants. Ahead, learn how and why to use easy-to-find soil amendments.

Wood Chips

Wood chips come from tree trunks, limbs, and branches about 12 inches in diameter and smaller. They should be allowed to age before using them in the garden. As the material sits for at least 6 months, beneficial organisms colonize it and begin the slow process of turning it into soil. Earthworms thrive in gardens with wood chips.

Mulch the soil surface with wood chips in a 2- to 4-inch layer around established plants. You often can get a free truckload of wood chips delivered from most tree-pruning and removal companies.

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Grass Clippings and Leaves

Use these two lawn waste items independently or together. For passive soil improvement, use a mower with a mulching deck to mow the lawn. A thin layer of mulched leaves returns nutrients to the soil and helps to conserve water. Mulched leaves boost the soil’s carbon content and improve the ground 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 in a 6-inch layer on an empty garden bed to improve the soil over winter.

soil amendments guide

Bone Meal 

Bone meal is a traditional organic fertilizer that boosts a soil’s phosphorus level. It is available anywhere that gardening supplies are sold. Before adding bone meal and other fertilizers, it is best to perform a soil test to ensure that the soil needs this nutrient. Plants use phosphorus to grow roots, flowers, and fruit. Apply bone meal at the beginning of the growing season for season-long plant nourishment.


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

Wood Ash 

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

A little goes a long way and you can harm soil if you add too much at once. Scatter wood ash fertilizer over the garden at about 20 pounds (5 gallons) per 1,000 square feet. Or, sprinkle some on the compost pile every time you add new waste.

soil amendments wood ash


Whether you make your own or buy it from a store, compost is one of the most familiar and beneficial soil amendments. Companies and home gardeners make compost from virtually any organic material— from weeds and veggie scraps to cardboard and sewage sludge—so quality, texture, and nutrient loads vary significantly.

Till compost into the soil before planting. Add it as mulch on the soil surface after planting, or brew it into compost tea for foliar feeding.

soil amendments compost


With the massive growth in online ordering, it’s great to know there is a way to use some of that packing material in the garden. Paper or cardboard can work as biodegradable weed barriers by simply layering it on the garden bed and covering it with 4 to 6 inches of wood chips or other organic materials. You also can shred paper or cardboard to add to the compost pile as a carbon source.