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 USDA zone info for River Forest should be reviewed to determine when it's possible to plant primula.

Planting Calendar for Primula

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

Primula do well in cold weather which means that you can plant them earlier in the year than other frost tender plants.

The earliest that you can plant primula in River Forest is February. However, you really should wait until March if you don't want to take any chances.

The last month that you can plant primula and expect a good harvest is probably September. You probably don't want to wait any later than that or else your primula may not have a chance to grow to maturity. Starting your primula indoors is a great way to get them started a few weeks earlier.

Last Frost Date

In River Forest the average date of last frost happens on April 15. In the coldest months of winter you should expect an average low temperature of -10°F.

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 River Forest and it can change quite a bit from year to year. Half of the time in River Forest you get a frost after April 15 so be sure to be ready to cover your primula if you have one of those late frosts.

USDA Zone Info for River Forest

Here is the info for USDA Zone 6a.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-10°F
Highest Expected Low	-5°F

This means that on a really cold year, the coldest it will get is -10°F. On most years you should be prepared to experience lows near -5°F.

Plants to Grow in River Forest

You may be interested in your other planting guides for River Forest.