For a successful garden, know your soil

Understanding your soil is a critical first step in building a successful garden.

Courtesy of Doreen Howard
Despite soil that has a high pH and is rocky, my garden thrives, because I amend the top of the ground to ensure plants' vigor and longevity.

As you flip through seed catalogs assembling this year's wish list, think about dirt. It’s the most important element for success with fruit, vegetables, and landscape plants. Find out what type of soil is in your garden. It affects how and what will thrive for you.

Eons ago, the Rock River Valley, where I live in northern Illinois, was carved out by the Wisconsin Glacier, leaving deposits of silt, sand, loam, and clay, along with plenty of tumbled rocks and limestone. Because of the glacier's action, yards here may have more than one soil type. Mine does.

My acre is at the steep end of a glacier moraine. The front yard is the outwash of the moraine where plenty of silt was deposited. The 18-inch layer sits upon four feet of sandy clay loam. The rest of the yard is the moraine end with an eight-inch layer of loam, on top of two feet of clay loam and more than five feet of gravely loam underneath.

The pH (measure of acidity or alkalinity) is high, because 40 percent of the soil is calcium carbonate (limestone). The front yard is much lower in lime concentration, only about 16 percent. In short, I have good soil in the front and challenges elsewhere due to high pH. Click here to see what high pH does to plants.

I found this detailed soil analysis at a United States Department of Agriculture website. They’ve mapped the country, analyzed soils, and made the data available to all in a free comprehensive report.

Click on the big WWS green start button, then click on Address to enter yours. A map will come up of your neighborhood. Click on the AOI button and place the red box around your yard. Then click on the Soil Map tab and follow directions.

At the end, click on Shopping Cart to order your custom report. Download it immediately or have it sent later via email. It’s free.

Once you know your soil type or types, you may have to improve the ground before planting. Amending a planting hole is a limiting action. Plant roots won’t spread beyond the altered soil.

Instead, dig a hole, insert plant, and backfill with excavated dirt. Improve the top of the ground in a five- to 15-foot radius, depending upon the mature size of the plant. Sprinkle sulfur to lower pH or add lime to raise it.

Top with a half-inch layer of compost or a scattering of slow-release fertilizer. See package for recommended amounts. Top that with organic mulch – two to three inches of shredded leaves or wood chips. Nutrients will filter into the soil, enticing new plant roots to grow outward.

Consider rubbing a mycorrhizal fungi inoculant on plant roots before putting them in the ground. The fungi are symbiotic, attaching to the plant roots, growing 20 feet or more in every direction to gather nutrients and water to feed the plant. It also thwarts many plant diseases. Look for mycorrhizae at garden centers that stock organics or do an Internet search for mail order sources.

Doreen Howard is one of eight garden writers who blog regularly at Diggin' It. If it’s edible and unusual, Doreen figures out a way to grow it in her USDA Zone 4b garden. She’ll try anything once, even smelly Durian. A former garden editor at Woman’s Day, she writes regularly for The American Gardener and The Old Farmer’s Almanac’s Garden Guide.

Editor’s note: To read more by Doreen Howard, click here. The Monitor’s main gardening page offers articles on many gardening topics. See also our blog archive and our RSS feeds. You may want to visit Gardening With the Monitor on Flickr. Take part in the discussions and get answers to your gardening questions. If you join the group (it’s free), you can upload your garden photos and enter our next contest.

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