When can I plant Sunflowers in Zone 1a

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

The USDA zone info for Zone 1a can be looked at to determine when to plant sunflowers.


Planting Calendar for Sunflowers

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

It's probably a bad idea to plant sunflowers until after the last frost when the weather gets warmer because they do not do well in cold weather.

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 1a is June. However, you really should wait until July if you don't want to take any chances.

The last month that you can plant sunflowers and expect a good harvest is probably July. 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 few weeks earlier.

Last Frost Date

In Zone 1a the average date of last frost happens on June 15. In the coldest months of winter we can expect an average low temperature of -60°F.

Since the USDA zone info for Zone 1a is not always accurate our actual date of last frost is different every year. Half of the time in Zone 1a it frosts late in the year after June 15 so make sure that you are prepared to protect your sunflowers if we have a surprise late frost.

USDA Zone Info for Zone 1a

Here is the info for USDA Zone 1a.

Average Date of Last Frost (spring)June 15
Average Date of First Frost (fall)July 15
Lowest Expected Low-60°F
Highest Expected Low-55°F

This means that on a really cold year, the coldest it will get is -60°F. On most years you should be prepared to experience lows near -55°F.

Plants to Grow in Zone 1a

You may be interested in our other planting guides for Zone 1a.