Garden Bed Spacing & Soil Calculator

How to Calculate Soil Volume for Raised Beds

Multiply length × width × depth, all in feet. A 4×8 bed that is 12 inches (1 ft) deep is 4 × 8 × 1 = 32 cubic feet. Divide by 27 to get cubic yards (32 ÷ 27 ≈ 1.2), which is how bulk yards and dump trucks price soil. For lumber, add up the perimeter — 2 × (length + width) — multiply by the number of board courses your depth needs, then divide by board length. Our deck and fence material calculator handles the same board-counting math for bigger builds, and if you plan to seal the outside faces of the frames, our paint and stain estimator will tell you how much finish to buy.

The Magic of Mel’s Mix: Why Square Foot Gardening Works

Mel’s Mix is one-third blended compost, one-third peat moss or coco coir, and one-third coarse vermiculite. The compost feeds, the peat or coir holds moisture while staying airy, and the vermiculite keeps the whole blend fluffy so young roots can push through easily. Combined with dense square-foot spacing, beds crowd out weeds, need less watering, and produce far more per square foot than rows. It costs more up front than topsoil, but the blend lasts for years with a simple compost top-up each season.

Plant Spacing Guide: Maximizing Yield in Small Spaces

Square-foot gardening replaces row spacing with a grid: 16 carrots per square foot (a 4×4 mini-grid), 9 bush beans (3×3), 4 lettuce heads (2×2), and 1 tomato or pepper per two square feet. Think of it as the baker’s-percentage logic of gardening — every input scaled to a fixed area. Dense planting only works in loose, rich soil, which is why the mix matters as much as the math. And when the harvest lands faster than you can eat it, our meal prep macro calculator helps you build it into the week’s menu.

Topsoil vs. Garden Soil vs. Potting Mix: What’s the Difference?

Topsoil is cheap screened dirt with inconsistent organic matter — fine for leveling, too dense for beds on its own. Garden soil is topsoil amended with compost, meant to be blended into beds (or used up to 50% of a raised bed mix). Potting mix is soilless and fluffy, designed for containers — excellent in pots but far too expensive and lightweight to fill a deep bed by itself. For raised beds, blend your own: a soil-based 50/30/20 mix or the soilless Mel’s Mix.

How to Protect Raised Beds from Weeds and Burrowing Pests

Start from the ground up: clear the area, lay overlapping cardboard to smother existing grass, then staple ½-inch hardware cloth across the entire bottom (bending it a few inches up the walls) before any soil goes in — the only reliable defense against gophers. After planting, a 1–2 inch straw mulch keeps weed seeds from germinating and slows evaporation. If you are also hardscaping a gravel work area around the beds, our patio and flooring calculator estimates base and surface material for that pad.