Soil for Greenhouse Gardening - Ask Extension
I have a greenhouse new this year in Muskegon, Michigan. Inside there are raised beds, 18 inches deep. What would be the best soil mix to fill them? W...
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Soil for Greenhouse Gardening #894368
Asked March 13, 2025, 11:00 PM EDT
I have a greenhouse new this year in Muskegon, Michigan. Inside there are raised beds, 18 inches deep. What would be the best soil mix to fill them? We have a local landscape company that has mulch, topsoil, manure, peet moss, sand, dolomite, etc. The beds are pretty big so I would prefer to get my supplies in bulk if possible. When I had raised beds outside, I just used a 50/50 mixture of topsoil and manure and everything grew fine, but I don't know if that was "correct" or would work in this situation. Thanks for the help!
Muskegon County Michigan
Expert Response
Hi Courney, Thanks for contacting Ask Extension.
Probably your best solution is a good topsoil topped off with one to two inches of compost. If the topsoil is sandy consider an additional inch of compost. Too much organic matter can be problematic by taking up too much nitrogen needed by the plants. It can also retain more water that the plants can withstand. Ask supplier if they have tested the properties of the soil and compost if not have get soil test (Home | MSU Soil Test).
Check out the following links:
Soil to Fill Raised Beds | University of Maryland Extension
FS1328: Soil for Raised Beds (Rutgers NJAES)
I hope this helps.
