How do I work out how many plants I need?

Divide the bed's area by the area each plant takes. On a square grid each plant takes spacing × spacing, so a 12 × 6 ft bed (72 sq ft) at 1.5 ft spacing needs 72 ÷ 2.25 = 32 plants.

What is triangular spacing?

Rows are offset by half a space, like a honeycomb. Each plant takes spacing² × 0.866, so the same bed holds about 15% more plants and fills in with fewer gaps.

Which spacing should I use?

Use the spacing on the plant tag or in our plant pages: it is the centre-to-centre distance at which neighbours just touch when mature. Closer spacing fills in faster but costs more.

For a single plant filling the whole bed, yes: the calculator rounds up so there is no gap. When several kinds share a bed, round each group to the nearest whole plant instead; rounding every group up is how beds end up crowded.

Free tool

Plant spacing calculator

Work out how many plants fill a garden bed from its size and the plant spacing, on a square or triangular grid, with a spacing table per 100 sq ft.

You need

32 plants

72 sq ft ÷ 2.25 sq ft per plant = 32, rounded up.

How it works

Every plant needs a patch of bed to itself. On a square grid that patch is spacing × spacing. On a triangular grid (rows offset by half a space) it is spacing × spacing × 0.866, so the same bed holds about 15% more plants and fills in with fewer gaps. Divide the bed's area by the patch size and round up.

If the plant shares the bed with others, set the share: a groundcover along a 12 ft front edge might take 25% of a 12 × 6 ft bed. Our plant lists do this for every plant at once, from each plant's own spacing.

Worked example

A 12 × 6 ft bed is 72 sq ft. At 1.5 ft spacing on a square grid each plant takes 1.5 × 1.5 = 2.25 sq ft, so you need 72 ÷ 2.25 = 32 plants. On a triangular grid each takes 1.95 sq ft, so 36.95 rounds up to 37 plants.

Plants per 100 sq ft

Spacing	Square grid	Triangular grid
0.5 ft (6 in)	400	461.9
0.75 ft (9 in)	177.8	205.3
1 ft (12 in)	100	115.5
1.5 ft (18 in)	44.4	51.3
2 ft (24 in)	25	28.9
2.5 ft (30 in)	16	18.5
3 ft (36 in)	11.1	12.8
4 ft (48 in)	6.3	7.2
5 ft (60 in)	4	4.6
6 ft (72 in)	2.8	3.2

More on spacing and bed layout: How many plants do I need for a garden bed?

Plant lists by condition

Sample beds of 12 × 6 ft with quantities worked out the same way as this tool.

All plant guides

Questions and answers

How do I work out how many plants I need?: Divide the bed's area by the area each plant takes. On a square grid each plant takes spacing × spacing, so a 12 × 6 ft bed (72 sq ft) at 1.5 ft spacing needs 72 ÷ 2.25 = 32 plants.
What is triangular spacing?: Rows are offset by half a space, like a honeycomb. Each plant takes spacing² × 0.866, so the same bed holds about 15% more plants and fills in with fewer gaps.
Which spacing should I use?: Use the spacing on the plant tag or in our plant pages: it is the centre-to-centre distance at which neighbours just touch when mature. Closer spacing fills in faster but costs more.
Should I round up?: For a single plant filling the whole bed, yes: the calculator rounds up so there is no gap. When several kinds share a bed, round each group to the nearest whole plant instead; rounding every group up is how beds end up crowded.