Potato Planting Calculator
Plan potato beds: plant count, seed weight, and harvest budget.
What it does
Potato beds are easy to overbuy or overplant. Seed comes by weight, harvest comes by plant, and the bridge between them is spacing geometry. A bed divided by the rectangle each plant owns tells how many pieces to cut and what the row might return.
The tool above does that division both ways. Enter area plus row and plant spacing in metric or imperial. It returns whole plants, seed weight at 50 g per piece, and a yield budget at 1.2 kg per plant. Defaults describe a 20 m2 bed at 75 by 30 cm, so the page opens solved at 88 plants, 4.4 kg of seed, and 105.6 kg of harvest.
Spacing is a tradeoff you control. Wide rows ease hilling, airflow, and blight control; tight plants raise count but shrink tubers and tangle vines. The example uses 75 cm rows (near 29.5 in) with 30 cm (near 11.8 in) in row spacing because that pairing suits hand hilled beds and matches extension tables for home gardens.
Both modes agree because defaults convert cleanly: 20 m2 mirrors 215.28 ft2, and the inch spacings mirror the centimeter ones. Every row on screen follows the active system, so seed reads kg in metric and lb in imperial. The imperial mirror needs 9.7 lb of seed for about 232.8 lb of potatoes.
Treat yield as a plan, not a pledge. Variety, certified seed health, water timing, beetles, and blight swing real digging day. Use the table to compare common spacings, buy a little extra seed, and rotate ground so potatoes follow legumes or grain rather than tomatoes or peppers.
How to use
- Pick metric or imperial.
- Enter the bed area.
- Enter row spacing and plant spacing.
- Read plant count first.
- Buy seed by the seed result plus a small spare.
- Budget harvest and storage from the yield result.
Formula
- Area
- Bed area: m2 metric, ft2 imperial.
- Row spacing
- Distance between rows: cm metric, in imperial.
- Plant spacing
- Distance between plants in the row.
- Seed
- Cut seed pieces at 50 g each.
- Yield rate
- Planning harvest rate per plant.
Spacings convert to meters (or feet) before dividing. Seed assumes 50 g cut pieces and yield assumes 1.2 kg per plant as planning rates from extension guidance. Variety, soil, water, pests, and season move real harvests, so the limits below apply.
Worked example
Example: 20 m2 bed at 75 x 30 cm
A 20 m2 bed uses 75 cm rows and 30 cm plant spacing. Seed pieces average 50 g and each plant is budgeted at 1.2 kg. Find plants, seed, and yield.
- Area per plant = 0.75 m x 0.30 m = 0.225 m2.
- Plants = floor(20 / 0.225) = floor(88.89) = 88.
- Seed pieces = 88 x 0.05 kg = 4.4 kg.
- Yield at 1.2 kg per plant = 88 x 1.2 = 105.6 kg.
- Imperial mirror: 215.28 ft2 at 29.53 x 11.81 in also gives 88 plants.
- That is 9.7 lb of seed for about 232.8 lb of potatoes.
Reference table
| Spacing (cm) | Plants | Seed (kg) | Harvest (kg) |
|---|---|---|---|
| 75 x 30 | 88 | 4.4 | 105.6 |
| 75 x 25 | 106 | 5.3 | 127.2 |
| 90 x 30 | 74 | 3.7 | 88.8 |
| 75 x 35 | 76 | 3.8 | 91.2 |
Limits
- Geometry only; soil and weather rule the harvest.
- Fixed 50 g seed and 1.2 kg yield planning rates.
- Ignores paths, edges, and compaction losses.
- No disease, pest, or frost modeling.
Common mistakes
- Mixing cm with inches in one run.
- Counting edge strips as full plant spots.
- Planting grocery tubers instead of certified seed.
- Skipping hilling, which greens tubers.
- Following tomatoes with potatoes in the same bed.
Try it yourself
Quick checks. Answers sit tucked under each question.
Half bed: 10 m2 at the same 75 x 30 cm?
44 plants. Seed 2.2 kg. Harvest 52.8 kg.
Big bed: 50 m2 at the same spacing?
222 plants. Seed 11.1 kg. Harvest 266.4 kg.
Row 90 cm instead of 75 cm on 20 m2? Work it by hand.
Area per plant = 0.9 x 0.3 = 0.27 m2. Plants = floor(20/0.27) = 74. Seed 3.7 kg, harvest 88.8 kg.
Questions
How is the plant count found?
Bed area divided by the rectangle each plant owns (row spacing times plant spacing), rounded down. Leftover strips at edges do not grow a plant.
How much seed do I need?
About 50 g per cut piece with two eyes each. The tool multiplies 0.05 kg by plant count, so 88 plants need 4.4 kg.
What yield per plant is assumed?
A planning rate of 1.2 kg per plant here (about 2.6 lb). Real harvest swings with variety, water, and blight pressure, so treat it as a budget, not a promise.
Does it work in feet and inches?
Yes. Pick imperial and enter square feet with inch spacings. The 215.28 ft2 mirror of the example also returns 88 plants.
Which spacing should I pick?
Widen spacing for large russets, tighten for small salad types, and keep rows wide enough for hilling and airflow.
Any planting tips?
Cut a day ahead, cure the cuts, plant eyes up 10 cm deep after frost, hill twice, and water steadily until vines yellow.