A 4x8 raised garden bed is one of the most popular sizes for backyard vegetable gardens, and it is also one of the easiest to calculate soil for once you know the formula. Here is how much topsoil and compost you actually need, plus a few tips for buying in bulk instead of hauling home a trunk full of bags.

Calculating Cubic Yards for a 4x8 Bed

A standard 4x8 raised bed with sides 12 inches tall holds about 1.2 cubic yards of soil. If your sides are only 8 inches tall, you are closer to 0.8 cubic yards. The basic formula is length times width times height, then divide by 27 to convert cubic feet into cubic yards. Rounding up slightly is smart, since soil settles over the first few weeks.

Topsoil, Compost, or a Blend?

Straight topsoil alone tends to compact and drain poorly in a raised bed. Most gardeners get better results mixing roughly half screened topsoil with compost, which adds nutrients and keeps the mix loose enough for roots to spread. Some raised bed gardeners also blend in a smaller amount of coarse sand for drainage in heavier soil mixes.

Buying in Bulk vs. Bags

A single 4x8 bed does not always justify a bulk delivery on its own, but if you are filling more than one bed, bulk topsoil and compost from a local supply yard is almost always cheaper per cubic yard than bagged soil from a hardware store. Many Murrells Inlet gardeners combine a bulk order with neighbors or use it to fill multiple beds at once.

Filling the Bed Without Wasting Material

Lining the bottom of a raised bed with cardboard or a thick layer of leaves before adding soil can reduce how much topsoil you need to buy while still giving roots plenty of room to grow. This works especially well for taller beds where the bottom few inches do not need the same nutrient-rich mix as the top layer.

Get Your Soil from C-Scapes Mulch & More

C-Scapes Mulch & More LLC carries screened topsoil, compost, and garden soil blends by the bag or the bulk yard in Murrells Inlet, SC. Bring your measurements in and staff can help you figure out exactly how much to buy for your raised beds.