Sizu Riatto
Grow by Numbers · Chapter 1

The Sowing Calendar

Sow a little, often, and in turn. An arithmetic sequence gives every sowing day; the crops' days give every cut day; counting the trays on the shelf each day tells you the shelf you need.

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Opens on the book's Microgreen Shelf. Change any number to your own and press Calculate.

The crops in turn: name, days from sowing to cut, and the grams a tray (for the month's harvest)

Enter the interval, the trays a sowing and the crops, then press Calculate.

The formula

  • Sowing n is on day (n − 1) × the interval (day 0, 3, 6 …): the n-th term a₁ + (n − 1)d
  • Its cut day = its sowing day + that crop's days
  • Trays standing on a day = trays a sowing × the sowings sown on or before that day and not yet cut (a tray cut in the morning frees its place for that day's sowing)
  • One rotation = the number of crops × the interval; average trays standing = trays a sowing × the sum of the crops' days ÷ the rotation
  • Steady harvest a day = trays a sowing × the sum of the crops' grams ÷ the rotation
The book's worked example, Chapter 1. Two trays every 3 days, the crops in turn radish → broccoli → sunflower → pea, a 12-day rotation: pair 1 radish sown day 0, cut day 9, pair 2 broccoli sown day 3, cut day 15, pair 3 sunflower sown day 6, cut day 16, pair 4 pea sown day 9, cut day 20. In the first 30 days: 10 sowings, 20 trays sown, 7 harvests (14 trays, 4,370 g). Never more than 8 trays standing, about 7 on average; then 200.8 g a day, 1,405.8 g (3.1 lb) a week.
Check it. Count the trays on Template A's busiest day by hand: it should match the most standing here. If it is more than your shelf holds, sow fewer trays or less often.

Honest limits. Days to cut are planning figures from seed sellers and extension guides; your room, light and seed lot will move them by a day or two. Cut by the tray, not the calendar. The Microgreen Shelf was worked out on paper from published figures, not grown by us: weigh and measure your own. Prices are illustrative US prices from October 2026, shown without a currency sign; put in your own. Everything stays in your browser: no sign-up, nothing stored.

These calculators go with Grow by Numbers (Make It Add Up, Book 1), where every number on this page is worked by hand.