When can I plant Cosmos in Zone 2b

One of the best tools that we have as gardeners to help us figure out our gardening schedule is the USDA zone info. The most important data that the zone info tells us is average last frost and the lowest expected temperature for our area.

A common way of determining when it's the best time to plant cosmos is to look at the USDA zone info for Zone 2b.


Planting Calendar for Cosmos

Frost tolerance for cosmos: Tolerant of a very small amount of frost.
When you should plant them: Up to 3 weeks before last frost.

You can plant cosmos slightly earlier in the year because they do ok in moderate cold.

JanFebMarAprMayJunJulAugSepOctNovDec
Legend 
A good time to plant cosmos
Possibly ok, but a risky time to plant cosmos
Probably not a good time to plant cosmos

The earliest that you can plant cosmos in Zone 2b is May. However, you really should wait until June if you don't want to take any chances.

The last month that you can plant cosmos and expect a good harvest is probably August. If you wait any later than that and your cosmos may not have a chance to grow to maturity. If you are starting your cosmos indoors then you might be able to get away with starting them a little bit earlier.

Last Frost Date

The average date of last frost is May 15 in Zone 2b. In the coldest months of winter we can expect an average low temperature of -45°F.

Since the USDA zone info for Zone 2b is an average our actual date of last frost will vary from year to year. Since half of the time in Zone 2b it frosts late in the year after May 15 be ready to cover your cosmos if we have a late frost.

USDA Zone Info for Zone 2b

Here is the info for USDA Zone 2b.

Average Date of Last Frost (spring)May 15
Average Date of First Frost (fall)August 15
Lowest Expected Low-45°F
Highest Expected Low-40°F

This means that on a really cold year, the coldest it will get is -45°F. On most years you should be prepared to experience lows near -40°F.

Plants to Grow in Zone 2b

You may be interested in our other planting guides for Zone 2b.