One of the first steps you take when you are estimating your gardening schedule is find your USDA Zone info. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

It's a good idea to figure out when you can plant centaurea by referring to the USDA zone info for River Falls.

Planting Calendar for Centaurea

Frost tolerance for centaurea:	Tolerant of some frost.
When to plant:	Up to 5 weeks before last frost.

You can plant centaurea a little bit earlier in the year because they are one of those plants that can tolerate a little bit of cold weather.

The earliest that you can plant centaurea in River Falls 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 centaurea and expect a good harvest is probably August. If you wait any later than that and your centaurea may not have a chance to grow to maturity. If you are starting your centaurea indoors then you might be able to get away with starting them a little bit earlier.

Last Frost Date

In River Falls the average date of last frost happens on May 15. It might get as low as -25°F during the coldest months of winter.

Since the USDA zone info for River Falls is not always accurate the actual date of last frost will vary from year to year. Half of the time in River Falls you get surprised by a frost after May 15 so just be sure to be ready to protect your centaurea in the event of one of those late frosts.

USDA Zone Info for River Falls

Here is the info for USDA Zone 4b.

Average Date of Last Frost (spring)	May 15
Average Date of First Frost (fall)	September 15
Lowest Expected Low	-25°F
Highest Expected Low	-20°F

This means that on a really cold year, the coldest it will get is -25°F. On most years you should be prepared to experience lows near -20°F.

Plants to Grow in River Falls

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