DibbleWhen to plant cosmos in Zone 10
In Zone 10, the last spring frost usually passes around January 31 and the first fall frost arrives around December 15, leaving about 318 frost-free days. The windows below are computed from those frost dates, with the same math the Dibble app uses.
Nearly frost-free. Grow cool crops in winter; summers are too hot for many vegetables.
Planting windows for cosmos in Zone 10
| Task | Window |
|---|---|
| Direct sow | Feb 7 to Feb 21 |
| Estimated harvest | Apr 18 to Jun 27 |
The harvest estimate counts 70 days to maturity, then a picking window of about 70 days. These windows use typical frost dates for Zone 10; Dibble pins them to your exact ZIP code.
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How to grow cosmos
Sow cosmos after last frost in lean soil, too much fertility means leaves, not flowers. Deadhead for continuous bloom.
Companion plants
Good neighbors for Cosmos:
Cosmos in nearby zones
Keep exploring
Cosmos: the full growing guide · The Zone 10 planting calendar · Every crop and zone
Plant at the right time this season
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Dates are estimates based on typical frost dates for the zone. Your yard has its own microclimate, so use them as a starting point and adjust as you learn your space.