How many plants do I need at 12 inch spacing?

One per square foot in a square grid — 100 plants for 100 sq ft, matching the University of Illinois Extension chart. Staggered (triangular) at 12 in it is 100 ÷ 0.866 = 116 plants.

How do I calculate plant spacing?

Square grid: plants = area ÷ (spacing in feet)². Triangular grid: plants = area ÷ (spacing² × 0.866). An 18 in spacing is 1.5 ft, so 100 sq ft takes 100 ÷ 2.25 = 45 plants square, or 52 staggered.

Is triangular spacing better than square spacing?

For ground covers and mass plantings, usually. Every plant is the same distance from its six neighbours, so the bed fills evenly with fewer bare gaps; it takes about 15% more plants. Illinois Extension recommends a staggered pattern for ground covers.

How far apart should I plant a hedge?

Closer than the shrubs' mature width. WSU Extension (C132) suggests about 18 in for low hedges 3–4 ft high and 3–4 ft for tall hedges. A 20 ft row at 18 in takes 14 plants (240 ÷ 18 = 13.3, so 13 spaces plus the end plant).

How many plants do I need at 9 inch spacing?

1.78 per square foot in a square grid — 178 plants per 100 sq ft (Illinois Extension's chart), or about 206 staggered.

Landscaping

Plant Spacing Calculator

Spacing decides how many plants you buy and how fast a bed fills in. In a square grid each plant takes spacing × spacing; stagger the rows in a triangular pattern and each takes spacing² × 0.866, so the same bed holds about 15% more plants and closes over sooner. Enter the bed or the row, the spacing on the plant tag and the pattern, and the calculator returns the plant count, plants per square foot and the gap between rows.

Worked example: 20 × 5 ft bed at 12 in

Step	Working	Result
Area	20 × 5	100 sq ft
Square grid	100 ÷ 1²	100 plants
Staggered (triangular) grid	100 ÷ (1² × 0.866) = 115.5, rounded up	116 plants
Row gap, staggered	12 × 0.866	10.4 in

Plants per 100 sq ft

Spacing	Square grid	Staggered grid
6 in	400	462
8 in	225	260
9 in	178	206
12 in	100	116
18 in	45	52
24 in	25	29
36 in	12	13

The square-grid column matches the University of Illinois Extension ground cover chart (400, 225, 178, 100 and 45 plants per 100 sq ft at 6, 8, 9, 12 and 18 in). Illinois recommends planting ground covers in a staggered pattern; staggering each row by half a space pulls the rows to 0.866 × the spacing, which is where the extra plants come from.

How far apart?

Use the spacing on the plant tag, which is set from the mature spread. WSU Extension's guide C132, “Spacing of Landscape Plants”, spaces low hedges (3–4 ft) about 18 in apart and tall hedges 3–4 ft apart, keeps small shrubs at least 2 ft from a foundation, and notes that 100 ground cover plants at 12 in cover about 100 sq ft. Closer spacing fills in sooner but costs more plants.

Mulch between the plants with the mulch calculator or pine straw calculator, and fill a new bed with the raised bed soil calculator.

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Frequently asked questions

How many plants do I need at 12 inch spacing?: One per square foot in a square grid — 100 plants for 100 sq ft, matching the University of Illinois Extension chart. Staggered (triangular) at 12 in it is 100 ÷ 0.866 = 116 plants.
How do I calculate plant spacing?: Square grid: plants = area ÷ (spacing in feet)². Triangular grid: plants = area ÷ (spacing² × 0.866). An 18 in spacing is 1.5 ft, so 100 sq ft takes 100 ÷ 2.25 = 45 plants square, or 52 staggered.
Is triangular spacing better than square spacing?: For ground covers and mass plantings, usually. Every plant is the same distance from its six neighbours, so the bed fills evenly with fewer bare gaps; it takes about 15% more plants. Illinois Extension recommends a staggered pattern for ground covers.
How far apart should I plant a hedge?: Closer than the shrubs' mature width. WSU Extension (C132) suggests about 18 in for low hedges 3–4 ft high and 3–4 ft for tall hedges. A 20 ft row at 18 in takes 14 plants (240 ÷ 18 = 13.3, so 13 spaces plus the end plant).
How many plants do I need at 9 inch spacing?: 1.78 per square foot in a square grid — 178 plants per 100 sq ft (Illinois Extension's chart), or about 206 staggered.

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