Compost

A transformational experience for your garden

By Marsha Goldberg, Fairfax Master Gardener
Ask a seasoned gardener to reveal the key to ensuring a bountiful garden, and their answer may very well be, “Compost!” Compost is the crumbly, nutrient-rich product that results when living matter decays and decomposes. So beneficial is it to plants that compost is often referred to as “gardeners’ gold.”

When you work compost into the soil of a new bed or use it as a top dressing on an existing bed, it can improve the texture or “tilth” of either sandy soil or soil with too much clay. Compost can also correct the pH level of the soil (a measure of its acidity), transforming ordinary garden dirt into an almost-perfect medium for growing most plants. The nutrients that compost contains become available to plants and may eliminate the need for additional fertilizer or other amendments. Another benefit: when you eat vegetables you grow using compost, you also ingest the vitamins and minerals that were in the compost. The process goes full circle when you put the vegetable scraps from your meal right back into your compost pile to begin the cycle anew.

So how do you get this garden miracle worker? You can buy bags of compost at a big-box store or garden center or have it delivered in bulk. Unless you are buying from a reputable dealer, however, the compost may contain fillers or, worse, pesticides or insecticides if the material from which it was made came from fields or trees that were sprayed. The good news is you don’t have to buy compost; the ingredients to make it are right at your fingertips, in your kitchen and your garden.

The amount of work you put into making compost will determine how long it takes for the raw materials to turn into the rich, brown material that your garden craves. If you pile up your lawn clippings in a corner of your yard and do nothing, it will decay in a year or two, depending on factors such as weather. Turning it for aeration will speed the process, as will adding chopped or shredded leaves that you collect in the fall. (Leaves that are not chopped will mat and impede air flow through the pile; small pieces of material will always decay faster than large pieces.) Garden debris such as grass clippings and spent plants that you cut back can supply nitrogen, while leaves and other woody materials supply carbon, so it is good to have a mixture of both. When building your pile, you should try to add about equal amounts of carbon materials and nitrogen materials by volume to your pile. That is, for every bushel of e.g., grass clippings, you can add one bushel of straw or shredded leaves or paper. If there is too much carbon, the pile will be slow to decompose while excess nitrogen can make your compost a bit stinky. If anything, err on the side of adding more carbon materials, as much as two parts carbon to one part nitrogen, to keep it from smelling bad. And, if you notice a smell at any time during the process, go ahead and add more brown ie., carbon materials. You may be confused by information that the ideal carbon-to-nitrogen ration is 25 or 30 parts carbon to one part nitrogen. However, this refers to the materials by weight, not volume, which is more difficult for gardeners to measure.

Kitchen scraps–including fruit and vegetable peelings–eggshells, tea bags, and coffee grounds are all great candidates for the compost pile, but do not use dairy products or meat, as these may contain unwanted bacterial. Fish, which will decompose quickly and attract helpful worms, is okay, but bury it deeply in the pile so as not to attract animals.

If you do not want to leave your compost exposed in your yard, you have many options to contain it. A bin of some sort makes sense because it is easier to turn compost in a bin. You can buy a commercial composting bin starting at about $100 online or at a big-box store, but it is easy to make one. The ideal size is a four-foot circle or cube. You can buy wire mesh, fasten it into a circle, and fill it with materials. To turn the pile, remove the mesh, move it next to the current pile, and fork the material from the pile back into the mesh circle. Another option is to make wooden bins from pallets that many stores provide for free. Fasten pallets together into a single cube to contain a small pile, or set up three in a row. In the latter case, put your raw materials in the first bin, fork it into the second one a week or two later, and then turn it into the third. The first bin becomes the repository for raw materials, the second contains the semi-decayed material, and the third stores the finished compost.

Other alternatives are buying the lumber for a bin and putting it together yourself, making a sturdy bin by stacking cinder blocks, or using bales of straw that will last a few years and can then be added to the compost pile. If you are concerned about animals getting into your pile, consider a closed plastic bin or make sure that your homemade bin has a base made of wire, use wire on the sides, and construct a cover for it. Hardware cloth, a type of wire screening with holes that are about 1/2 inch square is a good choice, although a bit pricey.

Remember, the more you turn and aerate a compost pile, the more quickly it will decompose. Wet it each time you turn it to keep it moist but not soggy. The compost is ready to use once you can no longer recognize the raw materials.

You can find more information and many ideas for building bins and making compost online. Try the Virginia Cooperative Extension and the University of Missouri Extension.

Resources
Backyard Composting, Ed Rishell, Master Gardener, Virginia Cooperative Extension
Making Compost From Yard Waste, Ed Rishell, Extension Master Gardener, Virginia Cooperative Extension
How to Build a Compost Bin, University of Missouri Extension
Composting, Diane Relf, Alan McDaniel, Virginia Tech
Compost: What Is It and What’s It To You, Virginia Cooperative Extension