When to Plant Cosmos in New Jersey
Delicate, daisy-like blooms that dance in the breeze. Cosmos thrive in poor soil and practically grow themselves.
The Short Answer
New Jersey Frost Dates
Your planting dates depend on which part of New Jersey you're in. Here are the frost date ranges by region:
| Region | Zones | Last Frost (Spring) | First Frost (Fall) |
|---|---|---|---|
| Northern New Jersey | 6a, 6b | Apr 20 - May 5 | Oct 5 - Oct 20 |
| Central New Jersey | 6b, 7a | Apr 10 - Apr 25 | Oct 15 - Nov 1 |
| Southern New Jersey | 7a, 7b | Apr 1 - Apr 15 | Oct 20 - Nov 5 |
Cosmos Planting Schedule for New Jersey
Northern New Jersey (Zones 6a, 6b)
Average last frost: Apr 20 - May 5 · Average first frost: Oct 5 - Oct 20
Central New Jersey (Zones 6b, 7a)
Average last frost: Apr 10 - Apr 25 · Average first frost: Oct 15 - Nov 1
Southern New Jersey (Zones 7a, 7b)
Average last frost: Apr 1 - Apr 15 · Average first frost: Oct 20 - Nov 5
Growing Cosmos in New Jersey
Cosmos in New Jersey's Climate
Cosmos are the zero-effort flower. Direct sow from mid-May. No fertilizer, no fussing, no deadheading necessary (though it helps). They grow 3-5 feet tall and self-seed prolifically. Perfect for filling unused garden edges with color and pollinator habitat.
Soil Considerations for New Jersey
Sandy soils in Pine Barrens. Clay in north. Acidic in south. Rich loam in central agricultural areas. The Garden State for good reason. Make sure soil has warmed to at least 60°F before planting cosmos outside.
New Jersey Climate & Growing Season
Moderate climate with maritime influence. Good growing season. Four seasons. Excellent for a wide range of crops. Cosmos cannot tolerate any frost, so wait until all frost danger has passed before transplanting outside. Watch local forecasts carefully in spring.
Growing season length varies across New Jersey: Northern New Jersey (6a, 6b) has a last frost around Apr 20 - May 5, while Southern New Jersey (7a, 7b) sees frost end around Apr 1 - Apr 15. This difference matters for cosmos — transplant timing shifts by several weeks across the state.
Growing Tips
Don't over-fertilize — rich soil produces more leaves and fewer flowers. Let some flowers go to seed for next year's crop.
Companion Planting
Plant cosmos alongside these companions for better growth:
The Bottom Line
Last reviewed: March 29, 2026