Planning your space
Measure a garden bed
A useful plant count begins with the growing space inside the boundary, not the outside dimensions of a frame. Take a few measurements before opening the calculator. It is easier to explain a modest count from clear measurements than a larger number from space you cannot actually use.
Reviewed Oct 27, 2026
Measure the space you will plant
For a rectangular bed, measure the usable inside length and width in one unit system. Keep wall thickness, paths, and areas you intend to leave clear out of that rectangle. If the bed is irregular, model a usable rectangular section or separate sections rather than pretending its entire outline is rectangular.
For a round container, measure the inside diameter across its center. Make clear whether a rim or inward-sloping wall reduces the area you want to use. The calculator represents a flat planting layout; it does not estimate soil volume, root depth, or structural loading.
Choose an edge allowance
The edge allowance is the minimum distance from a plant center to the modeled boundary. It is separate from the distance between plant centers. Decide it explicitly, particularly when you want room beside the bed edge or around a container wall.
A half-spacing allowance is a convenient geometric example, not a recommendation for every crop. A source may call for another arrangement, and the physical bed may have constraints that the simple shape does not describe.
Check an example you can count
For a 300 × 120 cm rectangle, choose 30 cm between plants, 30 cm between rows, and a 15 cm edge allowance. The first centers sit 15 cm from the edges. Along the length, centers run from 15 to 285 cm, giving ten positions. Across the width, four positions fit.
The result is 10 × 4 = 40 plant centers. This is a custom layout example. It does not say that 30 cm spacing is appropriate for a particular crop or that every position will produce a successful plant.
| Measurement | Example value |
|---|---|
| Inside length | 300 cm |
| Inside width | 120 cm |
| Plant spacing | 30 cm |
| Row spacing | 30 cm |
| Edge allowance | 15 cm |
Review the drawing and the assumptions
Compare the diagram with the real bed. Check the orientation, dimensions, row count, and any access space you meant to leave. The coordinate list is useful when a dot diagram is difficult to inspect or when you want to mark positions out with a tape measure.
Keep the layout with your plan and add a note about anything excluded from the shape. If you later change spacing or margins, recalculate before buying seed or seedlings. A saved old count should not become the assumed answer for a different arrangement.