Jean Keuhn, UM Extension Master Gardener in Anoka County, July 25, 2015
Composting is the natural breaking down of various organic materials (grass, leaves) into a dirt-like material that is beneficial to plant growth. Compost is dual purpose. It helps sandy soil retain moisture and clay soils drain better. While backyard composting is simple, it is not necessarily easy. It is work, but the end results are worth it.
First, select an area for your compost. Most city ordinances require it be 3 to 5 feet inside your property line. Up against your or your neighbor’s wood fence is NOT a good plan. The area should be at least partly sunny and open to rain and air circulation. Commercial bins work fine, but are not necessary. A 4 to 5 foot diameter circle of fencing will work, or a similar-sized square. Smaller than that will not heat up properly, and larger is harder to work.
What to put into your compost? In addition to grass and leaves, other organic matter such as small twigs, spent flowers and trimmings, straw, coffee grounds, eggshells, fruit peelings and vegetable scraps, shredded newspaper (black and white print), and very small amounts of wood ash. Most of us no longer bag our grass on a regular basis, so in the fall much of what we put into our compost is leaves. Leaves are great, but we need more nitrogen-rich items, so when your grass has gotten excessively long and you rake up the excess, toss that in the bin.
Layering is the key to a good working compost pile. You can start with 8 to 10 inches of leaves. Then add grass and other organic matter. Water until thoroughly wet, but not soggy, and then add more leaves, etc. Add 1/3 cup of 10-10-10 fertilizer and a shovel full of your garden soil to get your pile off to a good start. Avoid adding too much grass at any one time, as grass clipping compact tightly and limit air circulation, decomposition is restricted, and your pile may smell foul. The pile can be 4 to 5 feet high, watering between layers.
Never put any meat, bones, grease, dairy products or pet droppings into your compost. They attract rodents and other animals. Also avoid diseased or insect-infested plants and weeds with seeds as the pile may not heat up enough to destroy the problems.
Composing requires air, water and sun, so it is helpful if oxygen is added to the pile by turning it monthly. This is where having a second or even a third bin helps. Shovel the partially decomposed material into the second bin, pulling the cooler outer edges into middle and add moisture if needed. Mixing helps the pile decompose more quickly, heat up more completely and reach higher temps. It will take at least twice as long to decompose if it is not mixed.
Water the compost pile periodically to keep it moist but not soggy. Add finished compost to your gardens and enjoy the lovely results.
For more information, see: http://www.extension.umn.edu/garden/yard-garden/soils/composting-and-mulching-guide/