Is there more produce on a full-moon day?
No difference
Sowing and harvesting by the moon — the "agricultural calendar" and biodynamic farming — is folklore the world over. The waxing days before the full moon, the "fruit days," are said to be best for fruit. We test it against how much produce reaches the market: the daily wholesale volume of fruit and vegetables at Tokyo's central wholesale market.
Total wholesale volume (all produce)
- Average (whole period)
- 7,158,502 kg/day
- Baseline (same weekday & month average = 100)
- 100.0
- Full moon days (±24h)
- 100.7
- New moon days (±24h)
- 99.7
- Verdict for full moon days
- No difference
Vegetables (mostly leaf and root crops)
- Average (whole period)
- 5,546,536 kg/day
- Baseline (same weekday & month average = 100)
- 100.0
- Full moon days (±24h)
- 100.8
- New moon days (±24h)
- 99.7
- Verdict for full moon days
- No difference
Fruit (what the "fruit days" should favor)
- Average (whole period)
- 1,611,965 kg/day
- Baseline (same weekday & month average = 100)
- 100.0
- Full moon days (±24h)
- 100.5
- New moon days (±24h)
- 99.5
- Verdict for full moon days
- No difference
Data: 2004–2026, Tokyo Metropolitan Central Wholesale Market daily report (produce, all markets), 5,919 trading days
Act II: If not the moon, what moves the produce?
Came looking for a difference? Here is a real one.
×1.3
What moves arrivals most is the market's own opening rhythm: the busiest Monday runs about 1.3x the quietest Wednesday. Even the season is mild — the biggest month, December, is only about 1.1x the yearly average. It's the turn of temperature and sunlight, plus the market's calendar — not the lunar phase — that sets the volume.
If the "fruit days" worked, fruit is where the difference should show — yet fruit, too, is no different on a full moon. The lunar calendar simply isn't the field's calendar.
The full moon itself doesn't move the harvest. What turns the field is season and weather — the sun's round, not the moon's.
Farming by the moon
Deciding when to sow and harvest by the moon's phase is folklore the world over — Japan's old lunisolar farming calendar, and Europe's biodynamic agriculture (begun by Rudolf Steiner, popularized by Maria Thun's lunar planting calendar). The waxing days before the full moon, the "fruit days," are said to be best for fruit: the moon is imagined to draw water and life upward, swelling seeds and fruit.
If the moon really does ripen crops, those vegetables and fruit are harvested, carried to market, and sold at auction. So — around the full moon, the volume of produce reaching market ought to rise. We test that against some 22 years of daily wholesale volume at the Tokyo Metropolitan Central Wholesale Market, one of the largest produce markets in the world.
How this verdict is computed
- The data is the daily wholesale volume of produce (all markets) from the Tokyo market's "daily report" (2004–, Shift-JIS CSVs aggregated over every trading day). Besides the total, we split out vegetables (mostly leaf and root crops) and fruit — the crop the "fruit days" are supposed to favor.
- A produce market has a strong weekly rhythm (closed days) and seasonality (what's in season). So we take the average for the same weekday-and-month as the expected value, and compare actual ÷ expected as an index — the same adjustment used in the births, accidents and fish topics.
- Using the moon's age at noon Japan time, we mark "full-moon days" (the instant ±24h) and "new-moon days," and compare each group's mean index against the baseline (100).
See the methodology for the full criteria.
A caveat on the data
Market arrivals are a proxy for supply, not the harvest itself. There is a short lag from harvest to shipment and auction, and storable root crops and imported fruit flow decoupled from any single harvest date. Still, if the moon shaped the harvest, its shadow should fall across 22 years and thousands of trading days of arrivals — and if the "fruit days" worked, it should show in fruit first.
The real culprit: the season and the market's rhythm
What turns the field is not the lunar phase. It's the season — the round of temperature and sunlight — that decides what comes in, and how much. Fruit gathers in summer, leafy greens firm up in winter; that rhythm is stamped into the market's volume far more strongly than the full moon, layered with the market's own opening days. The lunar calendar simply isn't the field's calendar. What the moon genuinely moves is not the crop but the tide (→ tides).
Data sources
- Tokyo Metropolitan Central Wholesale Market daily report (daily wholesale volume, produce, all markets; source: Tokyo Metropolitan Central Wholesale Market)
- Lunar age and the instants of the phases are computed in-house from the algorithms in Jean Meeus, "Astronomical Algorithms" (UTC basis)
Last updated: June 14, 2026 01:17 UTC (rebuilt daily)