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Composting
Martha Maletta, Home Horticultural Consultant
Dated - October 05, 2004

What’s so good about compost? Gardeners generally seem aware that it’s beneficial to gardens, and making compost is an excellent way to dispose of yard and garden debris, including fallen leaves. But, what does compost actually do for gardens?

Compost, partially decomposed plant materials, is a source of soil organic matter, and organic matter is a vital component of healthy, productive soil. Most New Jersey soils will be improved with increased organic matter content. Organic matter affects physical, chemical and biological properties of soils.

Regular additions of compost to the garden will improve and help maintain good soil health, the soil properties that affect plant growth health. A healthy soil in good health is well-drained, well-aerated, fertile and “workable.” It is also less susceptible to erosion. Organic matter increases the nutrient-holding capacity of the soil and reduces fertilizer losses. It also increases the water-holding capacity of the soil and the amount of water that can be used by plants.

Organic matter is food for the very important soil bacteria, fungi and other organisms. It will help reduce some plant hazards such as excess fertilizer or other salts, some toxic substances, some disease causing organisms. Organic matter will supply some plant nutrients to the soil. However, compost is generally very low in readily available plant nutrients so may not substitute for fertilizer in the garden. Partially finished compost is a good mulch material, benefiting the soil in ways that non-organic mulches cannot, while controlling weeds and conserving moisture.

Why not add leaves and other plant materials directly to the soil instead of composting them? They will decompose in the soil, but the process takes time and may create a temporary nitrogen shortage for plants. Also, an active compost pile may heat up enough to kill many weed seeds and disease organisms, a benefit not realized from turning materials directly into soil.

Compost or some other organic matter source such as peat moss or composted manure should be added to gardens every year. Two to four bushels for 100 sq. ft. is a general guide. In areas that are not tilled regularly such as perennial gardens and shrub beds, use organic mulch materials. For lawns, leave the clippings instead of removing them; they provide organic matter and are a significant source of nitrogen, too.

Fall is the time to build a compost pile and use compost. Rutgers Cooperative Extension publications “ Home Composting”, “Backyard Leaf Composting” and “Using Leaf Compost” are available at county extension offices and on the web at There is also a new Cornell website on small scale composting that provides at lot of “how to” information:

The Cornell site addresses an issue not usually mentioned in home composting literature – human health and compost - and offers guidelines for minimizing potential risks, considered low, from bacteria and fungi in home-made compost. Do not compost “…raw poultry or meat wastes, pet feces, and plate scrapings from people who are ill.” Manage the pile so that it heats up and stays hot for a period of time. Wear gloves and wash hands after handling or working with compost. Those with weakened immune systems should use extra caution when working with compost. Let compost age for “…at least a year before use.”

October is a prime month for lawn and garden maintenance including lawn weed control. But, not all lawn weeds are created equal, at least in terms of susceptibility to weed control chemicals. Violets are a good case in point: None of the most widely used lawn herbicides are very effective against this plant. By contrast, dandelion is susceptible to all.

If you plan to do some chemical broadleaf weed control this fall while weeds are still growing and when day temperature is in the 70’s, be sure you know which weed…or weeds…you are dealing with in order to choose the best control product. The lawn should also be assessed for conditions that might be making it prone to weed invasion. At times there are factors beyond our control, such as drought, that lead to turf thinning and weed problems. But others such as improper fertility management, poor mowing or irrigation practices, or site conditions such as compacted soil or excess shade can lead to poor grass growth and weed invasion. Correcting these sorts of problems is the most important step in controlling weeds.

If the decision is made to use an herbicide, take the time to learn something about the materials and their proper use. Rutgers Cooperative Extension has three Fact Sheets that can help: Weed Control in Home Lawns; Broadleaf Weed Control in Cool Season Turfgrasses (includes herbicide susceptibility chart); Crabgrass and Goosegrass Control in Cool Season Turfgrass. These publications are available at or by sending a SASE to RCE Hunterdon County, PO Box 2900, Flemington, NJ, 08822. For help with weed identification, submit samples to the Rutgers Master Gardener Helpline office, located in Building 2 of the Rt 31 County Complex, M, T, Th, 9:00- 12:00 and Th, 12:30 to 3:30. To “do-it-yourself” visit and for photos of common weeds.

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