Advanced options
Grid (square) spacing suits raised beds worked from the sides; traditional row growing uses wider gaps between rows for hoeing access, so fits fewer plants in the same area. Spacings shown are typical final spacings: sow closer, then thin. Offsetting alternate rows (diagonal planting) squeezes in roughly 10% more.
What The Plant Spacing Calculator Works Out
- Plants that fit: the bed length and width each divided by the crop's final spacing, rounded down, and multiplied together for an equidistant grid. A 3 m x 1.2 m bed takes 40 lettuces on a 30 cm grid where row culture would manage twenty-odd.
- Layout: the grid as columns x rows. The spacing encodes the mature plant's footprint plus its appetite: brassicas and courgettes command their half-metre-plus because they fill it, while the fierce thinning of carrots and beetroot is about giving each root an uncontested ration of water and nutrients.
- Custom spacing (advanced): use the figure from your seed packet or vary it deliberately. Spacing is a control dial: onions grown close yield more, smaller bulbs, and cabbages tighten from dinner-plate to dense mini-heads.
- Edge margin (advanced): keeps a strip clear at the bed edges for plants that would otherwise flop over the boards or sit in the dry zone against timber.
- Offset (diagonal) layout (advanced): alternate rows nested half a space apart, rows 0.866 x spacing apart (hexagonal packing). It usually squeezes in 10% to 15% more plants than the square grid; the card shows the exact gain for your bed.
- Traditional rows (advanced): plants close within a row and a wide alley between rows for the hoe, the Victorian walled-garden pattern seed packets still describe. Edit the row gap (45 cm is typical) and compare the count with the grid.
- Square-foot method (advanced): the per-30 cm-square headcount (16 carrots, 9 beetroot, 4 lettuce, 1 brassica) multiplied by the number of squares in the bed.
- Plants to buy or raise (advanced): the grid count across all your beds plus a percentage of spares for slug losses and failures, costed at your price per plant or set. Module-raised veg plants typically cost GBP 0.30 to GBP 1 each; onion sets a few pence.
- Crop table (advanced): grid, offset and row counts for every listed crop in your bed. Crowding breeds mildew and botrytis and gives slugs a canopy to commute through, so airflow-hungry crops (onions ripening, strawberries fruiting) repay generous spacing.
Further reading: RHS: growing vegetables.