One set of calculations
The planner and spacing calculator use the same position-counting function. Distances are converted to inches internally. One foot is 12 inches and one inch is 2.54 centimetres. Unit changes convert measurements rather than relabel them.
Total capacity = length-axis count × width-axis count
If the margins cannot fit on an axis, that count is zero. The remaining distance is split evenly across opposite edges. Counts are whole numbers; no fractional plants are reported. Small numerical tolerance at arithmetic boundaries avoids floating-point conversion errors.
Mixed-crop layout policy
The planner creates full-length crop strips in list order. Every strip uses half-spacing margins and as many rows as the requested count needs, limited by remaining width. It uses no biological compatibility scoring. A trellis crop moves to the first strip and is restricted to one row. Requested, placed, and unmet counts are separate.
Unallocated area lies outside all crop strips. Vacant positions inside a partly planted strip are reported separately. No packing or yield optimum is claimed. Position coordinates are measured from the top-left inside corner of the diagram; the top is not automatically north.
Soil volume and purchasing
Order ft³ = base ft³ × (1 + allowance / 100)
Whole bags = ceiling(order ft³ / bag ft³)
One cubic foot is 28.316846592 litres. One cubic yard is 27 cubic feet. Bag rounding uses the full internal value, not displayed decimals. The base quantity and optional allowance remain separate. The planner’s soil summary uses exactly this calculation for its one bed.
Crop preset sources
- CSU Extension · Vegetable Planting Guide (GardenNotes 720)
Colorado guidance; block / close-row spacing. Source reviewed: September 2024. - CSU Extension · Block Style Layout (GardenNotes 713)
Colorado guidance; raised-bed block spacing. Source reviewed: April 2023. - UGA Extension · Home Garden Planting Chart (Bulletin 577)
Georgia guidance; traditional row spacing. Source reviewed: March 2022.
We use 18 crops. Block presets select the wider end of a published range where one is provided, using equal distances from GardenNotes 720 or head-lettuce spacing from 713. Traditional-row presets select published plant and row distances from UGA Bulletin 577, generally the wider end of ranges. These are separate methods and should not be blended into one recommendation.
Source data checked September 22, 2026. A source check means transcription and context were reviewed against the linked publication; it does not mean field testing or professional review of this site. Source review dates refer to the publishers, not Little Plot Works.
Regional and practical limits
Colorado and Georgia publications provide useful starting points, not a nationwide prescription. Variety, support, climate, soil and maintenance may require changes. User-entered spacing overrides presets. The tool does not calculate germination, yield, irrigation, nutrients, shade, or calendar suitability.
Practical software limits: bed sides up to 100 ft; spacing up to 600 in; 10,000 positions; 8 planner crop blocks; 20 soil bed types with up to 100 identical beds each; soil depth up to 120 in. Dense diagrams may show only a labelled sample of positions. Position downloads retain the full list.
Precision and examples
Displayed quantities are rounded for readability, typically to two or three decimal places. Bed and spacing conversions retain greater precision. Worked examples are mathematical examples, not tested garden outcomes. Treat measurement uncertainty and source suitability separately from arithmetic precision.
Result guidance
Besides the main result, the tools report guidance that is derived, not assumed. Each item is calculated by running the same engine again with one input changed:
- Marking out reads each strip’s position, rows, first plant centre and spacing directly from the calculated layout.
- Wider or longer bed searches for the smallest inside width, then the smallest inside length, at which every requested plant is placed, rounded up to a whole inch or centimetre and re-checked.
- Room to spare finds, for each crop on its own, the largest number of extra plants that can be placed without any other plant losing its place.
- Next row or plant in the spacing calculator applies the axis formula to find the extra length or width for one more position, then re-counts to confirm.
- Bag sizes in the soil calculator repeat the same rounding for other common bag volumes.
None of these suggest reducing spacing, and none add rules beyond those described above.
What you should verify yourself
- The inside dimensions of the real bed, and whether it is square.
- The spacing for your variety, from the packet or local advice.
- Which edge is the back, and what tall or trellised crops will shade.
- Planting and sowing times for your area.
- The supplier’s bag volume or bulk measure, and what the material contains.
Editorial corrections
We aim to correct reproducible calculation errors and misleading source interpretations. Send the inputs and source details to [email protected]. No response time or review credential is implied. Material calculation and data changes should update this page and the reference notes.