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Compost adds heap of nutrients to raised-bed gardens

Getting the right soil mix for your raised-bed garden can make all the difference in the success of your efforts.

Raised-bed gardens have a lot of advantages. They raise the plants up so it’s easier to work with them. The soil stays loose and friable with fewer weeds so plant roots can grow easily.

Why not use ordinary garden soil to fill a box? Ordinary garden soil is loaded with weed seeds as well as diseases and even bugs – all of which can make a mess out of your efforts. Ordinary garden soil may also contain a large amount of clay or silt that packs down in the box, closing off pore spaces that are needed to hold water and air for the roots.

Raised beds should therefore be filled with a weed-free mix of sand, loamy soil and compost. Known commonly as three-way mix, it is sold in bulk by soil companies for about $20 to $25 a cubic yard. A 4-by-8-foot box, 8 inches deep, will take just under a cubic yard of mix to fill. Three-way mix can however be heavy and a little short on nutrients. It may be advisable to add an equal amount of compost to the mix to improve its texture.

Compost is created from a wide variety of decomposed organic material. As interest in gardening and efforts to repurpose organic waste has grown, composts made from specific forms of organic waste have made their appearance in the market, giving gardeners a choice as to what to add to the soil mix. Locally we have at least four or five name brand composts available.

Eco Green Compost has been around the area for years. It is produced by the city of Cheney from clean green material and biosolids collected by the city.

If you are looking for a “certified” organic compost, Royal Organics is listed by the Washington State Department of Agriculture for use in organic production. It is made from clean green waste collected by a number of cities around the Northwest.

The ultimate form of recycling is available with Barr-Tech’s new offering of compost. The company is now handling all of the clean green waste from Spokane and turning it into compost at its facility near Fish Trap.

Cows in the dairy industry create a lot of manure. Organix Power Plant is made from manure, bedding and barn sweepings from dairy farms in the region. It is screened to remove water and then aged to create compost.

Lastly, a new “high tech” compost made from the anaerobic digestion of dairy manure will be available this spring. The waste from dairy cows in the Yakima area is run through the digester to pull off methane that is then used to generate electricity. The leftover material becomes compost.

These composts will be available at several local soil companies, so ask which ones they carry when you place an order. Prices will vary but are in the range of $30 to $48 a yard.

Pat Munts has gardened in the Spokane Valley for more than 35 years. She can be reached at pat@

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