Gardenia Organic

Plant spacing, mulch & gravel Calculator

Plant spacing, mulch & gravel calculator

Bed geometry, exclusions and supplier density → plant centers, material volume and tonnage.

Open full calculator · Calculation schema v2 · Sources checked 2026-10-28

Bed dimensions & plant centers

Both bed orientations are counted. Staggered grids also evaluate both parity offsets. Triangular row spacing is √3/2 × in-row spacing.

Paths & rectangular exclusions
Coordinates use selected bed units, measured from the same lower-left corner. Overlapping regions are unioned; boundaries exclude plant centers. Example for a center path in an 8 × 4 ft bed: 0, 1, 8, 2.

Material quantity

Density is an editable arithmetic example, not a preset guaranteed for this material. Match moisture and loose/compacted basis to the order. Non-bed footprints use their own net area and do not subtract bed paths.

Bag & bulk comparison

Independent two-component amendment mixer

B is the remainder to 100%. This quantity mixer does not predict nutrition, pH or final mixed-volume shrinkage.

JavaScript enables calculations and share links. The formulas and worked example below remain readable without it. Shared inputs stay in the URL fragment.

Enter your measurements, then select Calculate.

Your estimate

Plant-center capacity
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Best enumerated orientation
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Plantable bed and excluded area
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Finished material volume
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Order volume
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Mass: kg and metric tonnes
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US short and imperial long tons
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Bag quantity and cost
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Bulk order and cost
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Bag overbuy
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Amendment A quantity
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Amendment B quantity
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Assumptions and warnings appear after calculation.

Worksheet generation time appears after calculation.

Bed layout — calculate to show plant centers and paths
Plant centers are counted individually. Diagram axes are in meters.
Plant coordinates and alternative layouts

Formula and worked example

A 4 × 8 ft bed with 1 ft spacing and a 0.5 ft setback contains 32 centers. An 8 × 2 ft center path leaves 16 centers in the two 8 × 1 ft planting strips. The SVG and coordinate list show every counted center.

Finished volume = net area × depth. 20 m² × 0.05 m = 1 m³. With 10% extra order this is 1.1 m³; at a supplied 1,600 kg/m³ it weighs 1,760 kg. With 20% physical shrinkage instead: 1 ÷ 0.8 = 1.25 m³. Do not combine these assumptions unnoticed.

Metric tonne = 1,000 kg; US short ton = 907.18474 kg; imperial long ton = 1,016.0469088 kg. Bags round up; density is not a structural load approval. Read the gravel guide and layout guide.

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