Tokyo in September: what to plant
Over the last 5 years, September in Tokyo has run 21.6–28.8°C with about 202 mm of rain across the month. Here is what weather like that will carry to harvest.
Everything above is a five-year average. In the game it is this — the weather Tokyo is actually having, today.
Grow one in Tokyo's weather right now →❄️ No sub-zero nights in September in the last 5 years — frost is not the limiting factor here.
🗓️ This month sits inside the frost-free window. Average last spring frost around Feb 29, first autumn frost around Dec 14 — roughly 289 frost-free days. Sow tender crops after the last frost date and make sure they finish before the first.
☀️ About 8.1 h of sunshine a day this month. Within the month it cools by about 2.9°C from the first ten days to the last — the window for autumn sowings is opening.
Sow this month — when would you harvest?
Assuming you sow in mid-September, then adding up the warmth Tokyo usually gets, one day at a time — which is why some of these run past the end of the month.
| Crop | Days | Harvest around |
|---|---|---|
| 🌿 Amaranth greens | 62 | Nov 15 |
| 🧅 Onion | 158 | Feb 19 |
| 🏵️ Marigold | 44 | Oct 28 |
| 🌱 Microgreens | 5 | Sep 19 |
| 🌿 Garlic chives | 61 | Nov 14 |
| 🥬 Bok Choy | 25 | Oct 9 |
| 🥕 Carrot | 66 | Nov 19 |
⏳ Too late this month: Okra, Chili Pepper, Aubergine, Tomato, Sunflower would still be in the ground when the first frost arrives (around Dec 14). Sow them earlier in the year, or grow them under cover.
Best crops to sow now
- 🌶️ Okra Ideal about 74 days to harvest Recent mean 25.2°C — right in the sweet spot
- 🌶️ Chili Pepper Ideal about 96 days to harvest Recent mean 25.2°C — right in the sweet spot
- 🍆 Aubergine Ideal about 107 days to harvest Recent mean 25.2°C — right in the sweet spot
- 🍅 Tomato Ideal about 86 days to harvest Recent mean 25.2°C — right in the sweet spot
- 🌿 Amaranth greens Ideal about 37 days to harvest Recent mean 25.2°C — right in the sweet spot
- 🌻 Sunflower Ideal about 59 days to harvest Recent mean 25.2°C — right in the sweet spot
- 🧅 Onion Ideal about 53 days to harvest Recent mean 25.2°C — right in the sweet spot
- 🏵️ Marigold Ideal about 33 days to harvest Recent mean 25.2°C — right in the sweet spot
- 🌱 Microgreens Ideal about 5 days to harvest 🪴 Windowsill pot — sheltered from outdoor weather
- 🌿 Garlic chives Good about 43 days to harvest Recent mean 25.2°C — right in the sweet spot
- 🥬 Bok Choy Good about 23 days to harvest Recent mean 25.2°C — right in the sweet spot
- 🥕 Carrot Good about 45 days to harvest Recent mean 25.2°C — right in the sweet spot
Leave these for another month
- 🌿 Coriander — Recent mean 25.2°C is too hot (ideal 8–24°C)
- 🫘 Broad bean — Recent mean 25.2°C is too hot (ideal 6–22°C)
- 🥕 Parsnip — Recent mean 25.2°C is too hot (ideal 6–22°C)
Other months in Tokyo
📍 Somewhere else? Look up your own city →
Temperature and rainfall come from Open-Meteo's historical observations for Tokyo, averaged day by day over the last 5 years. Whether a crop finishes in time is worked out from its own starting temperature and heat requirement — those numbers are listed on each crop page if you want to check them.