The USDA Zone info is a great tool for gardeners to help us estimate your gardening schedule. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

By looking at the USDA zone info for Zone 3a you will be able to figure out when it's possible to plant onions.

Planting Calendar for Onions

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

Onions are one of those plants that can tolerate quite a bit of cold weather which means that you can plant them much earlier than plants that are more sensitive to the cold.

The earliest that you can plant onions in Zone 3a 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 couple of weeks earlier by starting your onions indoors.

Last Frost Date

On average the last frost when the weather gets warmer is on May 15 in Zone 3a. It might get as low as -40°F during the coldest months of winter.

Just be sure to remember that USDA zone info for Zone 3a is just an average and the actual date of last frost can change quite a bit from year to year. Half of the time in Zone 3a there is a last frost after May 15 so be sure to be ready to protect your onions in the event of a surprise late frost.

USDA Zone Info for Zone 3a

Here is the info for USDA Zone 3a.

Average Date of Last Frost (spring)	May 15
Average Date of First Frost (fall)	September 15
Lowest Expected Low	-40°F
Highest Expected Low	-35°F

This means that on a really cold year, the coldest it will get is -40°F. On most years you should be prepared to experience lows near -35°F.

Plants to Grow in Zone 3a

You may be interested in your other planting guides for Zone 3a.