Garden Q&A: Improve your garden soil this fall

QUESTION: I have heard fall is a great time to amend soil. Is this true, and how do I do it? - D.A., Rockford

ANSWER: Amending soil means improving the texture and organic nutrients in the soil, which are necessary to support ideal plant growth.

Depending on where you live, you may find the quality of soil in your gardens less than ideal. Particularly in areas of new construction your soil, like mine, may be heavily compacted limestone chunks with a scant layer of topsoil.

It's always best to test the soil to find out the nutrient and pH levels of your soil. Simple kits are available at home and garden centers. More extensive tests can be done through your local extension office. The tests will tell you what and how much to add to improve your soil. The fertility of your soil depends on the essential nutrients as well as its pH range.

Nitrogen is needed for healthy leaf and stem growth. It is water-soluble and therefore depletes readily from the soil. Phosphorus is required for healthy root growth and is essential for flower formation. Potassium helps sustain overall plant health by aiding in the development of the plant's immune system. It is also water-soluble and depletes over time.

The pH of your soil is the measure of how acidic or alkaline it is. This directly affects how well the plants can uptake the nutrients from the soil. Most plants prefer ranges between 5.5 and 7.5, or low acid to neutral soils.

Amending the soil texture means making the size of particles more like a bread-crumb mixture or sandy loam. It should be light and airy to allow movement of water, air and nutrients to the roots of the plants. You can accomplish this by adding organic material, such as "homegrown" compost, peat moss, composted barks, leaf or mushroom compost, straw, sawdust or cocoa shells. Add three to four inches of it to garden beds, working it into the top six to 12 inches of soil.

Composting is a great way to provide your soil with the organic nutrients it needs, as well as a great way to reuse and recycle common household trash like grass clippings, leaves, vegetable peels, coffee grounds and even newspapers. Compost is a great soil conditioner. It loosens the soil as well as increases worm activity and adds beneficial bacteria. You can get more specifics on how to compost from your local extension office.

This week's answer comes from Catherine Baer-Mirza, University of Illinois Extension Master Gardener, Winnebago County. Master Gardeners can be contacted weekdays at the University of Illinois Extension office at 815-986-4357. You can also bring your questions to the plant clinic on Thursday evenings from 6 to 8 p.m. at Sinnissippi Gardens, just south of the greenhouse.