DibbleWhen to plant cosmos in Zone 6
In Zone 6, the last spring frost usually passes around April 21 and the first fall frost arrives around October 17, leaving about 179 frost-free days. The windows below are computed from those frost dates, with the same math the Dibble app uses.
Generous season. Spring and fall plantings both productive.
Planting windows for cosmos in Zone 6
| Task | Window |
|---|---|
| Direct sow | Apr 28 to May 12 |
| Estimated harvest | Jul 7 to Sep 15 |
The harvest estimate counts 70 days to maturity, then a picking window of about 70 days. These windows use typical frost dates for Zone 6; 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 6 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.