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Rebuilding civilization

Water and food

Plants that fit in a plot

Number of plants and seeds from the area, the spacing and a square/rectangular or triangular layout.

m²

Square/rectangular: plants in a grid (rows and plants aligned). Triangular: each plant at the same distance from its six neighbours, in an equilateral triangle.

m

Examples: potato 0.7-0.8 m; tomato 1 m; lettuce 0.3 m; maize 0.75-0.9 m.

m

In the triangular layout, the distance between any plant and its neighbours. Examples: potato 0.3 m; tomato 0.5 m; lettuce 0.3 m; maize 0.25-0.3 m.

Seeds sown in each hole. Leave it empty for transplants or tubers.

%

Percentage of seeds that sprout. Test it by sowing 100 seeds on a damp cloth or in soil.

Result

Plants (or holes)
—
Plants per m²
—
Plants per hectare
—
Seeds needed
—
Holes that will stay empty
— %

How it is calculated

Square/rectangular grid: plants per m² = 1 ÷ (row spacing × plant spacing). Triangular layout with spacing d between plants: rows end up d × 0.866 apart and plants per m² = 1 ÷ (0.866 × d²) = 1.155 ÷ d², 15.5 % more than a square grid of side d. Plants = area × plants per m², rounded down.

Example. 100 m² of potatoes at 0.75 × 0.30 m: 1 ÷ 0.225 = 4.44 plants/m² → 444 plants. Triangular at 0.5 m in 10 × 10 m: 1.155 ÷ 0.25 = 4.62 plants/m² → 461 plants (versus 400 in a 0.5 m square grid).

Seeds. Seeds = holes × seeds per hole. The probability that a hole stays empty is (1 − germination)^seeds per hole: with 80 % and 2 seeds, 0.2² = 0.04, 4 %. With 444 holes, 888 seeds.

Keep in mind

  • The area-based calculation assumes edge plants sit half a spacing from the boundary. If you plant right on the boundary a few more fit; if you leave paths, subtract their area first.
  • The triangular layout makes better use of land for fruit trees, olives and round-habit plants; for crops that are hoed or earthed up with an implement, a rectangular grid gives better access.
  • The spacings in the help are approximate: they depend on the variety, irrigation and soil fertility. In poor rain-fed land, plant further apart.
  • If you sow several seeds per hole, thin to the most vigorous when they have 2-4 true leaves; the extra ones compete for water and light.

See also

More tools in “Water and food”