When can I plant Onions in Zone 3b

Before planting it is a good idea to find our USDA Zone info to figure out our garden 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 3b should be read to estimate when to plant onions.


Planting Calendar for Onions

Frost tolerance for onions: Very tolerant of frost.
When you should plant them: Up to 7 weeks before last frost.

Since onions do well in cold you can plant them earlier in the year than more sensitive plants.

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

The earliest that you can plant onions in Zone 3b is March. However, you really should wait until April if you don't want to take any chances.

The last month that you can plant onions and expect a good harvest is probably August. If you wait any later than that and your onions may not have a chance to really do well. You can get started a little bit earlier by starting your onions indoors.

Last Frost Date

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

Since the USDA zone info for Zone 3b may not be accurate from year to year our actual date of last frost is different every year. Half of the time in Zone 3b there is a last frost after May 15 so make sure that you are prepared to cover your onions if we have 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.