How much soil for a 3×3 raised bed

A 3×3 raised bed 12 inches deep needs 9 cubic feet of soil: 5 bags of 2 cubic feet, or about 0.3 cubic yards.

Fill it with a 1:1 mix of compost and garden soil or topsoil (University of Illinois Extension): 4.5 cubic feet of each. Illinois Extension also notes the bed settles as the compost breaks down, so plan to top it up each year.

At 3 feet wide this bed is reachable from both sides, within Illinois Extension's 4-foot limit for beds you can walk all the way around.

Soil for a 3×3 bed (3 by 3 feet)
DepthCubic feetCubic yards2 cu ft bags1.5 cu ft bags1 cu ft bags
6 in4.50.17335
8 in60.22346
10 in7.50.28458
12 in90.33569
18 in13.50.507914
24 in180.6791218

Cubic feet = length × width × depth in inches ÷ 12; cubic yards = cubic feet ÷ 27; bags rounded up. Bed sizes and fill: Ken Johnson, University of Illinois Extension, “Raised Bed Gardening” (July 2023). Soil calculator for any size.

What fits in a 3×3 bed

A raised bed has no rows, so we space plants the USDA in-row distance apart both ways, in a grid (our method, not USDA's). The range runs from USDA's widest to its closest spacing.

Plants that fit in 3 by 3 feet
CropSpacingPlants
Asparagus18 in4
Beets2–3 in144–324
Broccoli14–24 in1–4
Brussels Sprouts14–24 in1–4
Cabbage14–24 in1–4
Cantaloupe6 feet0
Carrots2–3 in144–324
Cauliflower14–24 in1–4
Celery4–6 in36–81
Chervil and Chives2–3 in144–324
Chinese Cabbage8–12 in9–16
Collard Greens1½–2 feet1–4
Corn Salad12 in9
Cucumbers3 feet1
Dandelion Greens8–12 in9–16
Eggplant3 feet1
Endive12 in9
Fennel4–6 in36–81
Garlic2–3 in144–324
Green Beans3–4 in81–144
Head Lettuce12–15 in4–9
Horseradish1½–2 feet1–4
Kale12–15 in4–9
Kohlrabi5–6 in36–49
Leeks2–3 in144–324
Lettuce6 in36
Lima Beans3–4 in81–144
Mustard Greens12 in9
New Zealand Spinach18 in4
Okra2 feet1
Onion Seed2–3 in144–324
Onion Sets2–3 in144–324
Onions2–3 in144–324
Parsley4–6 in36–81
Parsnips2–3 in144–324
Peas1 in1,296
Peppers1½–2 feet1–4
Potatoes10–18 in4–9
Radishes1 in1,296
Rhubarb3–4 feet0–1
Rutabaga2–3 in144–324
Salsify2–3 in144–324
Shallots2–3 in144–324
Sorrel5–8 in16–49
Soybeans3 in144
Spinach3–4 in81–144
Summer Squash (Zucchini)15–18 in4
Sweet Corn14–16 in4
Sweet Potatoes12–14 in4–9
Swiss Chard6 in36
Tomatoes1½–3 feet1–4
Turnips2–3 in144–324
Upland Cress2–3 in144–324
Watermelon2–3 feet1
Winter Squash2–3 feet1
Witloof Chicory6–8 in16–36

Spacing: USDA Home and Garden Bulletin No. 9 (1967), “Suburban and Farm Vegetable Gardens,” table 2. Plan this bed for your town · Spacing chart.

Updated