One of the first steps you take when you are figuring out 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.

A way of estimating when it's the best time to plant datura is to look at the USDA zone info for River Falls.

Planting Calendar for Datura

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

Since datura are barely cold tolerant you can plant them slightly earlier in the year than plants that are more sensitive to the cold.

The earliest that you can plant datura 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 datura and expect a good harvest is probably August. You probably don't want to wait any later than that or else your datura may not have a chance to grow to maturity. If you are starting your datura indoors then you might be able to get away with starting them a couple of weeks earlier.

Last Frost Date

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

Keep in mind that USDA zone info for River Falls is not always accurate and the actual date of last frost can change quite a bit from year to year. Since half of the time in River Falls there is a last frost after May 15 be ready to cover your datura 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.