Plant spacing calculator

Square grid or offset rows?

In a square grid every plant sits directly beside and behind its neighbours, which is easy to mark out and to weed between. In offset rows (also called triangular or staggered spacing) each row is shifted by half a spacing, so every plant is the same distance from six neighbours. The rows sit closer together, 0.866 of the spacing, and the pattern packs about 15.5 % more plants into the same area.

Offset rows are the standard for groundcovers and mass plantings, where the aim is an even carpet with no bare lanes. Square grids suit vegetables and anything you walk between. Either way, spacing is measured centre to centre, from the middle of one plant to the middle of the next.

Worked example: a groundcover bank

A 6 m × 2 m bank planted with groundcover tubestock at 40 cm in offset rows:

1. Density: 1.155 ÷ 0.4² = 7.2 plants per m². Times 12 m², that is 87 plants if the pattern ran right to the edges.
2. Real layout, keeping the outer plants 20 cm in from the edges: 17 staggered rows of 5 and 4 across the 2 m width, which is 77 plants. A square grid at the same spacing gives 75. On a narrow bank the offset pattern gains little.
3. With 10 % spare for losses, 85 plants. At $4 per tube that is $340.

The per-m² figure is what landscapers quote and what planting plans specify. The layout count is what you will actually plant. The calculator shows both.

Typical spacings

Always check the plant label first. It gives the mature width, and spacing at or a little under the mature width means neighbours just touch when fully grown. As a starting point:

Per-m² figures are for offset rows. Vegetable spacings assume a raised or well-prepared bed; in poor soil, or with plants bred to grow large, go to the wide end of the range.

Hedges: single or double row

A single row is enough for most garden hedges and is the easiest to maintain. A double staggered row puts a second row alongside the first, shifted by half a spacing, so the plants zigzag. It gives a denser, wider hedge faster and is common for windbreaks and wildlife hedges, but it needs almost twice as many plants and a wider strip of ground.

Hedge spacing is deliberately closer than the plants' mature width, so neighbours grow into each other and form one continuous screen. The calculator starts each row half a spacing in from the ends. If you want a plant right at both ends, against a post or a corner, divide the length by the spacing, add one and round up: a 10 m row at 60 cm becomes 18 plants set slightly closer together.

Closer spacing costs more, and saves time

Plant count rises with the square of the spacing. Halving the spacing from 60 cm to 30 cm needs four times as many plants. That trade-off is worth doing deliberately:

• Tubestock planted closer is often cheaper than larger potted plants at wider spacing, and it establishes faster in Australian conditions because the roots are not yet circling in a pot.
• Closer spacing shades out weeds sooner. Mulch the gaps in the meantime; the mulch calculator works out how much.
• Too close means competition for water and light, more disease in humid summers and a thinning-out job later. For vegetables, crowding is a false economy.

Spacing questions