Sandra Mason: Give soil a boost by adding organic matter

Sandra Mason: Give soil a boost by adding organic matter

As gardeners, we always want to add something to the soil. Like frustrated cooks looking for the perfect chili recipe, we add a dash of this and pinch of that. Before adding anything, it is best to get to know your soil. So tonight put your ear to the ground and listen carefully.

OK, just kidding on that one. First, get to know your soil with a soil test. Soil tests measure soil pH and the major nutrients used by plants (nitrogen, phosphorus and potassium). The results also may include calcium, sulfur and magnesium as secondary nutrients. Also, ask for organic matter levels, which should run 3 to 5 percent. Assorted soil testing labs are listed at

Generally, you can't go wrong by adding organic matter, as it adds important nutrients and microbes to the soil and helps with soil drainage. Think of feeding the soil rather than feeding plants with fertilizer. If possible, add organic matter to whole gardens rather than just the planting hole. Good soil in the planting hole but lousy soil all around encourages plant roots to stay in their happy planting hole, never to venture out into the cruel world.

However, some plants grow better without a lot of organic matter. Perennials with runners or rhizomes such as mint can get downright invasive if they are planted in soils with high organic matter. Lavender and baby's breath prefer a sandy, rocky soil.

Some common organic matter products added to soil:

Peat moss

Peat moss is partially decomposed sphagnum moss harvested from Canadian peat bogs. Peat moss is often recommended but comes with a huge environmental cost. Peat harvesting permanently changes the water relations of the bogs so that natural regeneration is impossible. It also degrades the area for the plants and animals that call the peatlands home.

Coco fiber

It is an environmentally sound byproduct of the coconut industry and makes a good substitute for peat moss. Coco fiber is sold in bricks, literally the size of house bricks, which are easy to transport and store. Once wet, the coco fiber swells to 3 cubic feet. Coco fiber is free of weed seeds and diseases and does a good job of holding nutrients and water in the soil. Add warm water and wait at least one hour to wet products thoroughly.


Ah, the elixir of the garden gods, also known as black gold, adds important nutrients and microbes to the soil. It also is the best solution for improving the drainage of clay soils. Make your own compost or buy local. Check with your city for municipal sources such as the Landscape Recycling Center, 1210 E. University Ave., U; phone 344-5323. Contact local livestock producers, but be sure to get composted manure such as Ewe Poo Compost (

Mushroom compost

Mushroom growers use their own special recipes to grow edible mushrooms. Once their harvest season is complete, the old compost is sold to garden centers, nurseries, etc. Mushroom compost can be good for garden soil; however, it can be too much of a good thing for seeds and seedlings.

Soluble salts and other nutrients in fresh mushroom compost may be too concentrated for seeds, immature plants and acid-loving plants such as rhododendrons and blueberries.

Be sure to mix mushroom compost with garden soil or check to see if your supplier has allowed the compost to continue to "ripen" for a couple months before usage.

Sale at Lincoln Square

The Grand Prairie Friends Native Plant Sale will run from 8 a.m. to 1 p.m. May 11 inside Lincoln Square Village in Urbana. The C-U Herb Society and other groups also will be there.

Plant sale in Danville

The Vermilion County Master Gardener Plant Sale will run from 7 a.m. to 1 p.m. May 11 at Crossroads Church, 3613 N. Vermilion St., Danville. Help fund local community garden projects.

Sandra Mason is unit educator, horticulture and environment, for the UI Extension, Champaign County. Contact her with questions or comments at 801 N. Country Fair Drive, Champaign, IL 61821, call 333-7672, email or fax 333-7683.

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