Before planting it is a good idea to find your USDA Zone info to determine your garden schedule. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

The earliest that you can plant onions in Princeton should be estimated by reviewing the USDA zone info.

Planting Calendar for Onions

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

You can plant onions quite a bit earlier in the year because they are very cold tolerant.

The earliest that you can plant onions in Princeton 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. Any later than that and your onions may not have a chance to grow to maturity. You can get started a little bit earlier by starting your onions indoors.

Last Frost Date

In Princeton the average date of last frost happens on May 15. You should expect an average low temperature of -30°F in the coldest months of winter.

Just be sure to remember that USDA zone info for Princeton is just an average and the actual date of last frost will vary from year to year. Since half of the time in Princeton you get a frost after May 15 be ready to protect your onions if you have a late frost.

USDA Zone Info for Princeton

Here is the info for USDA Zone 4a.

Average Date of Last Frost (spring)	May 15
Average Date of First Frost (fall)	September 15
Lowest Expected Low	-30°F
Highest Expected Low	-25°F

This means that on a really cold year, the coldest it will get is -30°F. On most years you should be prepared to experience lows near -25°F.

Plants to Grow in Princeton

You may be interested in your other planting guides for Princeton.