Seed Spacing Calculator
Plan your vegetable garden layout with correct plant and row spacing. Shows how many plants fit, seed packets needed and accounts for germination rates.
Using 80% default
Total Plants Needed
4
Seeds to Buy
Spacing Guide
Space seeds 45cm apart in rows 60cm apart. Account for germination failure by buying extra packets.
How Vegetable Spacing Works
Every crop has two spacings: between plants in a row, and between rows themselves. Carrots want 5cm between plants and 30cm between rows. Beans need 15cm and 45cm. Tomatoes go to 45cm and 60cm because their canopy is wider and the airflow gap matters for blight prevention. Get either dimension wrong and you either waste bed space or smother the plants.
Punching the bed dimensions and crop into the tool returns the row count, plants per row, and total plants. For a 2m by 1m bed of carrots that comes out at 3 rows of 40 plants, so 120 carrots in a small raised bed. The same bed planted with courgettes (90cm spacing both ways) fits just one plant - which is plenty, because each plant produces about 4kg of fruit over a season.
Why You Need More Seeds Than Plants
Germination rates aren't 100%. Parsnips germinate at around 60%, onions at 70%, carrots at 75%, beans and lettuce at 85%, potatoes at 90% (these are tubers, not seeds). To get 120 carrots in the ground you actually need to sow around 160 seeds. The calculator factors this in automatically using the typical rate per crop, but you can override it if you have fresh, professionally produced seed (often higher) or older packet stock from your shed (often lower).
A standard British seed packet contains roughly 50 to 200 seeds depending on the crop. The tool assumes 50 seeds per packet for the conservative estimate. Old seed loses viability fast: parsnip and leek seed is essentially dead after 12 months, while tomato and bean seed stay viable for four to five years if stored cool and dry. Always do a paper-towel germination test on packets older than two years before relying on them.
Frequently Asked Questions
How many tomato plants in a 1m by 2m bed?
Tomatoes need 45cm between plants and 60cm between rows, so a 1m by 2m bed fits one row of four plants. That is enough for a household of four to five through summer. If you cordon-train them up canes you can drop the plant spacing to 40cm and squeeze in five, but yield per plant drops as competition increases.
Can I plant closer than the recommended spacing?
Square Foot Gardening tightens spacings considerably (carrots at 7.5cm both ways, lettuce at 15cm) but it relies on enriched, deeply dug soil and consistent watering. Standard packet spacings are conservative and assume average soil. Closer planting works in raised beds with good compost; in heavy clay you should respect the recommendations or you will see disease and stunted growth.
Do I need to thin seedlings?
Yes for most direct-sown crops. Carrots, beetroot and parsnips are sown thicker than needed because germination is patchy, then thinned to final spacing once the seedlings have two true leaves. Snip the unwanted seedlings at soil level rather than pulling, which can disturb the roots of those staying. Thinnings of carrots and beetroot are edible.
How deep should a raised bed be for these crops?
Most veg are happy in 30cm of soil. Carrots, parsnips and longer beetroot want 45cm. Salads, radishes and herbs cope in 20cm. If you are planning a new bed see the [Raised Bed Calculator](/raised-bed-calculator) for soil volume and material costs.
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