One of the best tools that you have as gardeners to help us determine your gardening schedule is the USDA zone info. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

By looking at the USDA zone info for River Falls you should be able to estimate when it's a good idea to plant blue lace flowers.

Planting Calendar for Blue Lace Flowers

Frost tolerance for blue lace flowers:	Tolerant of a very small amount of frost.
When to plant:	Up to 3 weeks before last frost.

Since blue lace flowers do ok in moderate cold you can plant them slightly earlier in the year than more sensitive plants.

The earliest that you can plant blue lace flowers in River Falls is April. However, you really should wait until May if you don't want to take any chances.

The last month that you can plant blue lace flowers and expect a good harvest is probably August. Any later than that and your blue lace flowers may not have a chance to grow to maturity. You can get started a couple of weeks earlier by starting your blue lace flowers indoors.

Last Frost Date

The average date of last frost is May 15 in River Falls. In the coldest months of winter you should expect an average low temperature of -25°F.

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 last frost occurs after May 15 so make sure that you are prepared to protect your blue lace flowers in the event of 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.