Plant Spacing Calculator
Give it your bed size and a crop and it tells you how many plants fit, draws the layout to scale, and shows the spacing you actually end up with. Row spacing and square foot gardening are both covered, and they give different answers on purpose.
Bed size and crop
How this is calculated
Row spacing mode uses two different numbers, because plants are not round holes in a grid. In-row spacing is how far apart plants sit along a row. Between-row spacing is how far apart the rows sit, and it is almost always larger, because it has to carry your feet, a hoe and the plant's mature spread.
With the recommended half-spacing edge allowance the arithmetic is rows = bed width divided by between-row spacing, rounded down, and plants per row = bed length divided by in-row spacing, rounded down. That reserves half a spacing at each edge so the outermost plants get their full share of room. With the tight allowance it becomes rows = (width minus 4 inches) divided by between-row spacing, rounded down, plus one, which fits more plants but leans the outer ones over the edge of the bed.
Square foot mode ignores between-row spacing entirely. That is the whole idea of the method: with no paths inside the bed, the only number that matters is the in-row spacing, applied in both directions. So the plants per square is 12 divided by the in-row spacing, rounded down, then squared. A 3 inch crop gives 16 per square, 4 inches gives 9, 6 inches gives 4 and 12 inches gives 1. Crops needing more than 12 inches take a block of squares instead.
Square foot mode will always fit more plants, sometimes several times more. That is not free. It assumes a deep bed of rich compost-based mix, vertical support for anything that climbs, and consistent feeding and watering. In ordinary garden soil those numbers produce small plants.
Every result shows the spacing you actually achieved as well as the spacing the crop wanted, because the rounding always leaves a little slack, and knowing where it went is the difference between a plan and a guess.
Spacing for every crop
This is the same table the calculator runs on, so the two can never disagree. Figures are typical ranges from US cooperative extension guides. Your seed packet may differ and it knows your specific variety.
| Crop | In-row | Between rows | Square foot | Notes |
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Keep planning
Spacing decides how many plants. These decide everything else about the bed.
Common questions
Why do seed packets and extension guides give different spacings?
Because they are answering different questions. Seed companies usually publish the spacing that produces the best individual plant of that variety under good conditions. Extension guides tend to publish spacing for a whole planting, which factors in machinery, airflow and disease pressure across a bed rather than one perfect specimen. Neither is wrong. This tool uses the extension figures and shows a range in the table, because a confident single number here would be false precision.
What actually goes wrong if I crowd plants?
Airflow, mostly, and airflow is the main lever a home gardener has over fungal disease. Leaves that stay wet for hours after dew or rain are where powdery mildew, downy mildew, early blight and septoria get started, and crowded plants stay wet far longer. Beyond that, crowded plants compete for light, water and nutrients, which shows up as smaller fruit, later maturity and a harvest that arrives all at once instead of over weeks. The plant count is easy to increase. The airflow is not.
Can I really fit 16 carrots in one square foot?
Yes, and it works, provided the bed is genuinely deep, loose, compost-rich mix rather than ordinary garden soil, and you thin honestly. Carrots at 3 inches apart in both directions are a standard intensive spacing. Where square foot numbers fall down is with the large crops. One tomato in a single square foot is possible with a strong cage, relentless pruning and regular feeding, and it is not what most people should attempt on their first bed.
Should rows run along the length or the width of the bed?
This tool runs them along the length, which is the usual choice and normally fits more. If your bed is wider than it is long, swap the two numbers you enter and compare. It is also worth running rows north to south where you can, so the plants shade each other less through the day, though bed shape usually wins that argument in a small garden.
What is a good bed width?
Four feet is the standard for a reason: most adults can reach the center from either side without stepping in, and standing on the soil is what compacts it. If your bed is against a fence or wall and reachable from one side only, 2 to 2.5 feet is the honest limit. A 5 foot bed looks efficient on paper and turns into a bed you tread on.
Does the tool account for a trellis?
Partly. Cucumbers appear twice, on the ground and trellised, because the difference is large and real. For beans and peas the figures already assume vertical support, since almost nobody grows pole beans flat. For anything else, going vertical mainly buys you between-row space rather than in-row space, so use the tight edge allowance and expect a modest gain rather than a transformation.
My bed is narrower than the between-row spacing. Now what?
The recommended allowance will report zero rows, which is accurate rather than helpful, so switch to the tight allowance and you will get one row down the middle. A single row of a wide crop in a narrow bed is a perfectly good plan, and it is what most people do with tomatoes in a 2 foot bed against a wall.
Where do these spacing figures come from?
They are typical published ranges from US cooperative extension vegetable guides, which is why the reference table shows a range rather than one number. Where sources genuinely disagree, and they do, the table shows the spread instead of picking a winner. Your own seed packet is more specific than any general table because it knows your variety, and it should win.