One of the first steps you take when you are estimating your gardening schedule is find your USDA Zone info. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

The USDA zone info for Princeton can be looked at to determine when it's a good idea to plant nierembergia.

Planting Calendar for Nierembergia

Frost tolerance for nierembergia:	Not tolerant of frost.
When to plant:	After the last frost.

You really shouldn't plant nierembergia until after the last frost has passed because they are not cold tolerant.

The earliest that you can plant nierembergia in Princeton 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 nierembergia and expect a good harvest is probably August. You probably don't want to wait any later than that or else your nierembergia may not have a chance to fully mature. You can get started a few weeks earlier by starting your nierembergia indoors.

Last Frost Date

In Princeton the average date of last frost happens on May 15. It might get as low as -30°F during the coldest months of winter.

It's important to remember that the actual date of last frost may not be accurate from year to year because it is based on the USDA zone info for Princeton and it will vary from year to year. Since half of the time in Princeton last frost occurs after May 15 be ready to protect your nierembergia in the event of one of those late frosts.

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.