NiwaSquare foot gardening spacing chart
Square foot gardening reduces all vegetable spacing to four numbers: 1, 4, 9 or 16 plants per square. Here is the full chart, the logic behind it, and the crops that break the rule.
Mel Bartholomew's insight was that conventional row spacing exists to accommodate a hoe, not a plant. Remove the rows and you can grow the same yield in about twenty percent of the space, as long as you get the density right.
The whole system reduces to one question per crop: how many of these fit in a one-foot square? The answer is always 1, 4, 9 or 16.
Where the four numbers come from
Take the spacing on the back of a seed packet and divide twelve inches by it:
| Seed packet says | Per square foot | Grid |
|---|---|---|
| 12 in / 30 cm apart | 1 | Centre of the square |
| 6 in / 15 cm apart | 4 | 2 × 2 |
| 4 in / 10 cm apart | 9 | 3 × 3 |
| 3 in / 7.5 cm apart | 16 | 4 × 4 |
Ignore the "row spacing" figure on the packet entirely. That number assumes you are walking between rows. In a raised bed you are not.
The full spacing chart
1 plant per square foot
| Crop | Note |
|---|---|
| Tomato | Must be staked or caged to hold one square |
| Pepper & chilli | Both sweet and hot |
| Aubergine | Full sun, needs the heat |
| Broccoli | One head per square |
| Cabbage | Smaller varieties can be tight at 1 |
| Cauliflower | Heavy feeder |
| Rosemary, sage, oregano | Perennial: give it a permanent square |
| Potato | Or 1 per square in a deep bed |
| Okra | Tall: put it on the north edge |
| Sunflower (large) | Shade risk, plan for it |
4 plants per square foot
| Crop | Note |
|---|---|
| Lettuce (head) | Loose leaf can go to 4-9 |
| Swiss chard | Cut and come again |
| Basil | Pinch it or it bolts |
| Kohlrabi | Fast: good succession crop |
| Garlic (elephant) | Standard garlic goes at 9 |
| Marigold | Pest deterrent around tomatoes |
| Corn | Needs a block of squares for pollination |
| Parsley, thyme, coriander | Coriander bolts fast: succession sow |
| Strawberry | Perennial: runners need managing |
9 plants per square foot
| Crop | Note |
|---|---|
| Bush beans | Pole beans go vertical instead |
| Beetroot | Thin to 9; each seed is a cluster |
| Spinach | Cool season only |
| Turnip | Roots and greens both usable |
| Peas | Trellis them and 8-9 works |
| Garlic (standard) | Autumn planted, long occupancy |
| Rocket / arugula | Very fast, resow every 3 weeks |
16 plants per square foot
| Crop | Note |
|---|---|
| Carrot | Sow thickly, thin to 16 |
| Radish | 25-30 days: the best filler crop there is |
| Onion (bulbing) | From sets or transplants |
| Spring onion | Can push to 36 if you harvest young |
| Chives | Perennial clump |
| Parsnip | Slow: occupies the square all season |
Crops that break the rule
Some plants need more than one square, and pretending otherwise is the most common square foot gardening failure:
| Crop | Squares needed |
|---|---|
| Courgette / summer squash | 2 squares, or 1 with aggressive pruning |
| Winter squash, pumpkin | 4-9 squares, or trellis it |
| Melon | 4+ squares, or vertical with slings |
| Cucumber (bush) | 2 squares |
| Rhubarb, artichoke | 4 squares, permanently |
| Sweet potato | 4+ squares of vining |
A single unpruned courgette will cover nine square feet by August. If your bed is 32 squares, that is a quarter of your garden spent on a vegetable you will be leaving on neighbours' doorsteps by September.
Growing up instead of out
Anything that vines can be trellised, which converts a horizontal spacing problem into a vertical one. On a trellis at the north edge of a bed:
- Pole beans: 8 per square foot along the base
- Peas: 8 per square foot
- Cucumbers: 2 per square foot vertical, versus half a plant per square sprawling
- Indeterminate tomatoes: 1 per square, but three feet taller
- Small winter squash: 1 per square with fruit slings
Vertical growing roughly triples the yield of a small bed. It also improves airflow, which cuts fungal disease more than any spray will.
Where people get the chart wrong
- Sowing the final number of seeds. Germination is never 100%. Sow two or three seeds per position and thin to the target count. Thinning feels wasteful and is not optional.
- Filling every square on day one. Radishes are done in a month. Lettuce in six weeks. Leave a few squares for succession sowing or you get one enormous harvest and then an empty bed.
- Applying the chart to poor soil. These densities assume a rich, deep, well-drained mix. In thin or compacted soil, drop one density level or every plant competes and none produce.
- Forgetting the roots below. Sixteen carrots per square works only in eight or more inches of loose soil. In a shallow bed, use a shorter variety rather than a lower count.
Using the chart without looking it up
A chart is a lookup table, and lookup tables are what phones are for. In Niwa the density is a property of the plant, not something you apply.
Then work back the other way: as squares free up, Niwa still knows what grew there, so your follow-on crop respects both spacing and rotation.