When people ask what they can do to improve their gardens, to increase yields or grow healthier ornamental plants, the answer is almost always: Improve your soil by adding organic matter.
Making compost is the best way to create organic matter. It is cost-effective, and we have the ingredients right at home. Making leaf mulch or leaf mold is the easiest option in fall, but composting leaves produces higher organic matter.
Autumn is a good time to get compost piles off to a quick start because a key ingredient is in ample supply: leaves. Leaves are rich in carbon, phosphorus and potassium, nutrients plants need. Grass clippings and other green materials are sources of nitrogen. The best organic matter is created from a combination of brown and green materials. Compost also needs oxygen and moisture.
Finished compost takes between a month and a year, depending on how often it is turned and how well moisture is maintained, the Wisconsin Department of Natural Resources (DNR) says in its Home Composting guide.
January will mark the 20th anniversary since the state banned leaves, grass clippings, garden debris, twigs and brush from landfills or incinerators in 1993. More than 300,000 tons of yard materials are recycled each year. Choose one of these options:
“Hot” or fast composting is ideal for those with much yard material, limited space for a compost pile, who want a finished product in a short amount of time. It requires active work and frequent turning. A hot pile can make finished compost in two to six months.
“Slow” composting simply involves layering green and brown yard materials as they accumulate. Be sure to cover or mix in food scraps, and keep moist. After one or two years, the material in the bottom and center of the pile will be ready to use.
Here are tips and answers to common questions about home composting:
*– The fastest-cooking compost recipes call for two-thirds brown material, such as leaves, dried plants and vines, straw, and wood chips. Use one-third green material, such as grass clippings, fresh vegetable and fruit scraps, green garden debris and coffee grounds. Think of this 2:1 brown-to-green ratio by volume, not weight.
*– A compost pile can be started any time. In fall, save several bags of leaves so you can add carbon to your pile the following summer when grass and garden debris are abundant.
*– Turn materials every one to two weeks if using an enclosed bin, or every two to three weeks if using a pile or open bin, the DNR guide advises.
*– Water compost so it is moist as a wrung-out sponge. Materials become inactive if they are too dry.
*– Home compost piles usually freeze during Wisconsin winters. They will restart on their own when they thaw in spring. The DNR says 64 cubic feet of materials is needed to prevent freezing. Even then, decomposition slows.
*– When adding food scraps, bury them eight to 10 inches in the center of the pile, by turning the material. Or cover food scraps with a layer of dried leaves, hay or other carbon.
*– Be cautious about adding weeds to compost. Dry them on pavement, then add later. Avoid adding diseased plant material or highly invasive plants to compost. If your compost pile does not get hot enough, it might not kill the pathogens or seeds.
*– Invasive plants like garlic mustard or glossy buckhorn should be double-bagged and placed in the garbage.
*– Small amounts of native plants and weeds that produce toxins, such as black walnut or butternut leaves, nightshade and monkshood, can be added to compost.
*– Low-nitrogen material such as sawdust, straw and ground corn cobs may be added.
*– Crush egg shells, and grind or chop corn cobs. Mixing them with shredded leaves helps them break down faster.
*– Avoid adding ashes from charcoal grills or wood stoves. They’re acidic and break down slowly. If you do add small quantities, mix well with shredded leaves.
Limit use of pine needles in compost. They are high in acid and resin and difficult to compost. The best use of pine needles is to leave them under the tree where they fall to condition the soil and protect the shallow root system of their parent tree, the DNR says. Pine needles are good mulch for acid-loving plants such as lilies of the valley, blueberries, raspberries, blackberries, roses and conifers.
*– Do not compost dog, cat or other pet waste, meat or meat products, dairy products, and oil or grease.
*– Dryer lint and small amounts of newspaper and cardboard can be composted. Tear or shred the paper products, and wet all three of these materials when adding.
*– Some compost recipes include small amounts of garden soil; others say more than half a shovel of soil slows the composting process. No composter starter or activator is needed.
*– Coffee grounds are considered green material, a source of nitrogen. Coffee filters are brown material.
*– Grind or shred your leaves to speed the compost process. A mower or hoe can be used.
Depending on the time of year, you may have too much of one type of material, and not enough of another. The DNR offers these suggestions for balancing compost:
Not enough grass – Add another nitrogen source, such as two inches of livestock manure per 25 square feet of surface area. If you don’t have manure, consider nitrogen supplements such as dried blood, cottonseed meal or bone meal. Add roughly two cups of natural nitrogen supplement to each wheelbarrow of leaves.
Not enough leaves – Grass is high in nitrogen and compacts easily. Mix with bulking material such as wood chips, twigs or dried plant stalks to provide a carbon source and allow air to circulate.