Project guide
Filling raised beds without paying planting-soil prices for the bottom two-thirds.
The mistake is filling a two-foot raised bed entirely with bagged planting mix. It costs several times what it needs to, and plants never use the bottom foot anyway. Layer it instead, and buy the bulk portion by the cubic yard.
Fill dirt for the bottom half if the bed is deep, screened topsoil for the growing layer on top. For beds under twelve inches, skip the fill and use topsoil throughout. Add your own compost to the top six inches; we do not sell amended planting mixes.
A 4 by 8 ft bed at 18 inches deep is 4 x 8 x 1.5 / 27 = 1.78 cu yd. Split it: roughly 1 cu yd of fill dirt below and 1 cu yd of topsoil above, ordering 2 of each if you are doing two beds. Topsoil settles, so order slightly heavy.
Set the bed frame on level ground and line the base with cardboard to smother grass. Add fill dirt to roughly half the depth and water it in so it settles now rather than in June. Top with screened topsoil, mixing compost into the upper six inches. Water thoroughly and let it stand a week before planting, because fresh fill always drops an inch or two.
Raised Garden Beds — common questions
Fill dirt or clean subsoil for anything below about twelve inches. Plants do not root that deep in a raised bed, and filling the whole depth with topsoil or planting mix is money spent on nothing.
At 18 inches deep, 1.78 cubic yards. Round to 2 and split it between fill below and topsoil above.
No. Our topsoil is screened native soil with rock and root removed. It is a base to amend, not a finished planting mix. Add your own compost.
Yes, one to three inches in the first month. Water it in when you fill, and plan to top up before planting.
Pick your material, enter how many cubic yards and see the delivered number before you talk to anyone.