compost bin susan ask garden climate change
Compost helps recycle nutrients and adds organic matter to the soil. (photo by susan ask)

Compost is an excellent soil amendment for building healthy soil. Anyone interested in healthy, economical or do-it-yourself landscapes should explore the easy benefits of using compost. Compost will help replenish and rejuvenate the soil in your lawn and garden. Like commercial fertilizer, compost contains nutrients that feed the soil and help all of your plants. But—compost has other benefits, too.

what is compost?

compost is the material created from the decay of organic material through a controlled process. The result is a rich soil amendment.

benefits of compost

Organic matter in compost helps the soil hold on to water, nutrients and air—the building blocks of a healthy plant community. Worms and other good bugs thrive in compost, to the benefit of your garden, and microbes in the compost can also help suppress plant disease. Compost improves soil condition—helping loosen clay soil while helping sandy soil hold on to nutrients and water.

Compost add organic matter to the soil, which helps store moisture and nutrients. (photo by susan ask)

Compost also contains the three big soil nutrients—nitrogen, phosphorus and potassium—along with essential micronutrients. The nutrients are released slowly, unlike synthetic fertilizers which tend to be fast-release. Fast release fertilizers can cause a quick green-up, but the nutrients aren’t available for long-term health. And quick release fertilizers can cause significant water pollution when the nutrients wash away with rainwater and irrigation runoff.

And, compost has a smaller carbon footprint than synthetic fertilizer.  Plus, composting food scraps and yard waste keeps valuable resources out of landfills and reduces the greenhouse gases that go along with transporting and burying waste.

how to get compost

You can make compost at home, or buy it in bags or in bulk at most hardware stores or garden centers.

If you are making your own compost, you’ll know that it is ready to use when it is dark and crumbly. It should smell good and earthy, without mold or ammonia. If you can still recognize leaves and food scraps in the compost— mix the material and let it sit and work a little longer. If there are twigs in the compost, consider sifting the compost through a screen (use a screen with holes that are ¼” to 1” wide; hardware cloth works well) to separate the slow-to-break-down woody material from the finished compost.

Keep your soil in good shape with compost. Here’s how.

On new garden beds and new turf

Dig or rototill in 1-3 inches of compost when you’re making new beds or planting new lawns on bare soil in the spring and fall.

In garden beds

Add up to 3 inches of compost to your vegetable or flower garden before you plant new plants. You can also ‘side dress’ with compost by adding a bit of compost near existing plants that have been in the ground for a month or two.

Some gardeners and professional landscapers recommend putting some compost in the freshly-dug holes when transplanting. There isn’t much research on the effect and some people are concerned that the roots won’t grow out of this crumbly-textured ‘teacup’. If you decide to use this technique, aim for a mix of 25% compost and 75% soil when you fill in the hole around your new plant.

As mulch

Spread a layer of compost 1 – 3 inches thick around trees and shrubs. Don’t pile up the compost around the trunk; instead, spread the compost in an even layer to avoid creating a ‘volcano’ looking pile of compost. You can cover the compost with woodchips if you prefer the look of woodchips.

On existing lawns

With a rake, spread a thin layer of compost (1/4 inch is good, but up to 1/2 inch is fine) onto grass to enhance nutrient supply, increase aeration and water holding capacity, and promote the development of beneficial soil organisms. It’s best to do this in the spring and fall. Ideally, this should be done after core aerating the lawn.

If you have a standard Chicago lot, it’s easy to make enough compost for your lawn. If you have a big suburban lawn, you’ll probably have to buy compost. Consider shrinking your lawn so that it’s big enough for picnics and playing ball, then investing in natural lawn care to keep it healthy. You can convert the rest of your yard to low maintenance gardens and habitat.

For houseplants

Use a mix of 25% compost and 75% peat-free potting soil to help houseplants hold water, nutrients and air. Houseplants lead a tough life, being confined to a pot, so you’ll want to give them a boost with some compost or compost tea every year.

last updated April 2015