Posted 18 March 2016 - 03:34 AM
What soil mix are you using?
1/3 - 1/3 - 1/3
prominent raised bed gardening expert, Mel Bartholemew (author of the popular gardening classic Square Foot Gardening), recommends that you fill your raised beds with something he calls Mel’s Mix.
Mel’s Mix is (by volume) 1/3 coarse horticultural vermiculite, 1/3 peat moss, and 1/3 blended compost.
He recommends mixing the ingredients thoroughly and using at least 5 different sources of compost to provide a variety of nutrients (bagged compost often comes from a single source, such as cotton burrs or chicken manure, so it is a good idea to get a variety of sources and of course make your own compost at home to serve as one of your five sources).
Mr. Bartholemew says that the compost in his mix provides all of the fertilizer or nutrients that the plants will ever need, and that the only thing you will need to add to his mix over time is a little more compost each season (as the original compost breaks down and is used up by your plants).
He also says that his mix only needs to be 6 inches deep, never needs to be tilled, and that your raised bed bottom can be lined with landscaping fabric or cardboard so that the roots of the plants don’t even reach into your native soil.
As an aside, I might note here that some sources would call Mel’s Mix “soilless” because it does not contain “field soil”, like that found in your yard or garden. Other sources say that if a mix contains compost (as Mel’s does), then it cannot be considered soilless.