One of the best tools that you have as gardeners to help us determine your gardening schedule is the 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 River Falls should be reviewed to estimate when it's a good idea to plant sweet williams.

Planting Calendar for Sweet Williams

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

Since sweet williams are one of those plants that can tolerate a little bit of cold weather you can plant them just a bit earlier in the year than more sensitive plants.

The earliest that you can plant sweet williams 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 sweet williams and expect a good harvest is probably August. If you wait any later than that and your sweet williams may not have a chance to really do well. You can get started a few weeks earlier by starting your sweet williams indoors.

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 just an average the actual date of last frost is different every year. Half of the time in River Falls there is a last frost after May 15 so just be sure to be ready to protect your sweet williams if you have a surprise late frost.

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.