When can I plant Sunflowers in Zone 3b

The USDA Zone info is a great tool for gardeners to help us determine our gardening schedule. The zone info helps tell us things like average date of last frost and lowest expected temperature for our area.

It's possible to determine when you can plant sunflowers by using the USDA zone info for Zone 3b.


Planting Calendar for Sunflowers

Frost tolerance for sunflowers: Not tolerant of frost.
When you should plant them: After the last frost.

Since sunflowers are not cold tolerant it's important to wait until after the last frost before you can plant them.

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

The earliest that you can plant sunflowers in Zone 3b 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 sunflowers and expect a good harvest is probably August. If you wait any later than that and your sunflowers may not have a chance to grow to maturity. If you are starting your sunflowers indoors then you might be able to get away with starting them a little bit earlier.

Last Frost Date

In Zone 3b the average date of last frost happens on May 15. We should expect an average low temperature of -35°F in the coldest months of winter.

Always keep in mind that USDA zone info for Zone 3b is not always accurate and our actual date of last frost will vary from year to year. Half of the time in Zone 3b last frost occurs after May 15 so make sure that you are ready to cover your sunflowers in the event of a late frost.

USDA Zone Info for Zone 3b

Here is the info for USDA Zone 3b.

Average Date of Last Frost (spring)May 15
Average Date of First Frost (fall)September 15
Lowest Expected Low-35°F
Highest Expected Low-30°F

This means that on a really cold year, the coldest it will get is -35°F. On most years you should be prepared to experience lows near -30°F.

Plants to Grow in Zone 3b

You may be interested in our other planting guides for Zone 3b.