Garden Bed Planner & Calculator
Size the bed once, then get the soil to fill it, the plants that fit, and the lumber to build the frame. Every number shows the assumption behind it.
Your bed
Soil mix
Plants
Frame lumber
Common questions
How much soil do I need for a 4x8 raised bed?
A 4 by 8 foot bed filled to 10 inches needs about 26.7 cubic feet, which is roughly one cubic yard, or 36 bags at 0.75 cubic feet. Fill an inch or two below the rim so watering does not wash soil over the edge, and add around 10 percent because a fresh mix settles hard in its first season.
How many tomato plants fit in a 4x4 garden bed?
Four. Square foot gardening allows one indeterminate tomato per square foot, but most growers give them more room than that, so four plants in a 16 square foot bed with sturdy support is realistic. Crowding tomatoes cuts airflow and invites disease faster than it adds yield.
What is Mel's Mix for square foot gardening?
Equal parts by volume of compost, peat moss or coco coir, and coarse vermiculite. The compost feeds, the peat or coir holds moisture, and the vermiculite keeps the mix open so roots get air. Blend it on a tarp before filling, and use compost from several sources if you can.
Write the numbers down
The free Backyard Project Planner has a materials table and an order of work to drop this estimate into.