A 4x8 bed holds 32 square feet of planting and a 3x6 holds 18, and the square-foot method tells you exactly how many plants go in each one: 1 tomato, 4 lettuces, 9 beets or 16 carrots per square. Tall crops go on the north edge so nothing gets shaded.
Below is the spacing chart, four plans you can plant straight from — a summer and a fall plan for each bed size — plus path widths, soil depth and trellis placement.
Plants per square foot
One square foot is the unit. Divide it into 1, 4, 9 or 16 depending on how much room the mature plant needs, and plant on those centres rather than in rows. Rows waste the space between them; a raised bed is too valuable for that.
| Per square | Crops |
|---|---|
| 1 | Staked tomato, pepper, broccoli, kale, cabbage, cauliflower, eggplant |
| 2 | Cucumber, when trellised |
| 4 | Leaf lettuce, Swiss chard, basil, marigolds, strawberries |
| 8 | Peas and pole beans, trellised |
| 9 | Bush beans, spinach, beets, onions, garlic, turnips |
| 16 | Carrots, radishes |
Two things break the grid, and it is worth knowing before you plant them. Sprawling squash and pumpkins want two squares each or a trellis. Indeterminate tomatoes hold to one square only if you stake them and keep them pruned to a single stem — let one sprawl and it will take four.
Four plans you can plant from
Each square is one foot. The number in the corner is how many plants go in that square. North is the top edge in every plan, which is where anything climbing belongs.
4x8 bed — spring and summer
Tomatoes, cucumbers and peas along the north edge on a trellis. Peppers and basil behind them, then the low crops stepping down to carrots and radishes on the sunny south side. Marigolds at the end earn their square.
4x8 bed — fall and cool season
Brassicas take over the space the tomatoes had. Broccoli, cabbage and kale need a square each and will hold through light frost. Spinach and lettuce fill the middle, and the last three squares go to garlic, which sits over winter and comes out the following summer.
3x6 bed — spring and summer
Eighteen squares, and the same logic in less room. A 3-foot width means you can reach the middle from either side without standing on the soil, which is the main reason not to build wider than four.
3x6 bed — fall and cool season
A cool-season bed that keeps cutting well past the first frosts. Chard and kale in particular get sweeter after a cold night.
How much room to leave between beds
Measure between the bed edges, not between the plants — crops will lean out over the path by midsummer and eat whatever margin you left.
- 18 to 24 inches — enough to walk down and kneel beside.
- 36 inches — enough for a wheelbarrow, which you will want the day you bring in compost.
Soil depth by crop
Depth decides what you can grow more than width does. A 5-inch bed grows excellent salad and no carrots worth pulling.
| Depth | What it will grow |
|---|---|
| 6 in | Lettuce, spinach, radishes, most herbs, onions, garlic |
| 10 to 12 in | Carrots, beets, bush beans, peppers, cucumbers, brassicas |
| 18 in or more | Tomatoes, squash, potatoes, parsnips |
If a bed is sitting on open ground rather than a hard surface, roots will push down past the frame into the soil beneath, so a shallower bed goes further than the number suggests. On a patio or a deck, the depth you build is the depth you get.
Put the trellis on the north side
This is the cheapest mistake to avoid. Anything tall casts a shadow, and in the northern hemisphere that shadow falls north. A trellis on the north edge throws its shade outside the bed. On the south edge it shades everything behind it for the whole season.
If the bed runs north to south rather than east to west, put the trellis at the north end and accept a slightly shorter run of it.
Which bed to plant these in
The plans above map onto real beds like this.
| Bed | Size and depth | Plans it fits |
|---|---|---|
| Cedar Raised Garden Bed Kit — Deep | 36 x 72 in (3 x 6 ft). 5 in as two beds, 10 in stacked | Both 3x6 plans. Stack it for carrots and tomatoes |
| 2-Pack Metal Raised Bed, 8 x 4 x 2 ft | 4 x 8 ft, two of them. 24 in deep | Both 4x8 plans, with depth to spare |
| Farmhouse 4-Piece Elevated Planter Set | Four boxes, about 20 x 12 in each. 23.5 in tall | Herbs and salad at waist height, not a full plan |
One honest note on the elevated planter set: it is four separate boxes of about 20 by 12 inches, not a single 4x8 bed. It is genuinely good for herbs and cut-and-come-again salad at standing height, and it suits a patio or a balcony where a ground-level bed will not go. It is not what the plans above are drawn for.
Once the beds are in, overwintering your pots covers the containers that sit alongside them, and the five-zone backyard layout is a useful way to decide where the growing zone sits against everything else.
Common questions
How wide should a raised bed be?
Four feet at most, and three is better if you can only reach it from one side. The limit is your arm, not the plants — once you have to stand on the soil to reach the middle you are compacting the thing you just built.
How many plants fit in a 4x8 raised bed?
Thirty-two squares, so anywhere from 32 tomatoes at one per square to 512 radishes at sixteen. A realistic mixed summer bed holds roughly 8 to 10 large plants, a dozen medium ones and two or three squares of roots.
Do I need to leave space between the squares?
No. The spacing inside each square already accounts for the mature plant, and a closed canopy is an advantage — it shades the soil, holds moisture and crowds out weeds.
Can I plant a fall bed straight after pulling the summer one?
Yes, and you should. Top up with an inch or two of compost to replace what the summer crop used, then plant. The main constraint is your first frost date, not the soil.
See the full range of frames, kits and elevated planters in garden beds.