Polytunnel planting planner: make a bed grid (UK)

Use the spacing you intend to plant

Enter the bed length and width in metres, then the row and plant spacings in centimetres. Use figures from your seed packet or a checked crop source. The pre-filled numbers are arbitrary examples, not a recommendation for any crop.

There are no verified crop presets yet. This tool counts positions in a rectangular grid; it does not decide which crop or spacing suits your growing conditions.

Read the result across the bed, then along it

“Length” and “width” are the two entered axes; they do not have to mean the long and short sides. The tool counts rows across the width axis, with row lines running parallel to the length axis. Rotate a bed layout by swapping its entered length and width.

It rounds each count down to a whole number, then multiplies the two.

Rows = bed width in centimetres ÷ row spacing, rounded down.

Plants per row = bed length in centimetres ÷ plant spacing, rounded down.

Total spaces = rows × plants per row.

The count uses a half-spacing allowance at each edge. Where positions fit along an axis, the diagram centres them: each margin is half a spacing plus half of any leftover distance after rounding down. The bed is drawn to its entered proportions, but the screen and printed image do not have a fixed physical scale. The calculation does not include paths, staggered rows, mixed-crop arrangements or a separate border around the bed.

For a fuller explanation of input axes, remainders and rotated examples, see planting positions in a bed.

An arithmetic example

A bed 3 m long and 1.2 m wide, with rows 30 cm apart and plants 30 cm apart, gives four rows of ten positions: 40 spaces. This illustrates the arithmetic only. It is not a crop-spacing recommendation.

If either bed dimension is smaller than the corresponding spacing, the result is zero. That follows from the half-spacing allowance at both edges; it is not a judgement about whether a plant could grow there.

View, save or print the plan

After calculating, the diagram shows the bed outline and centred positions in relative proportion. For grids over 1,000 positions, it keeps the full outline and exact count but omits the individual points from the drawing.

You can explicitly choose Download SVG plan or Print this plan. The first asks your browser to save an SVG file; the second opens its print flow. The calculator does not automatically store inputs or results. Use the labelled dimensions rather than measuring the screen or printout.

Crop recommendations will be added only after dated RHS or seed-company guidance has been checked and recorded. Until then, bring your own verified spacing and use the result as a count to review.