One of the first steps you take when you are making a decision about 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.

In Great Falls you can figure out when you can plant datura by referring to the USDA zone info.

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.

Datura are one of those plants that can tolerate a tiny bit of cold weather which means that you can start planting them slightly earlier than other frost tender plants.

The earliest that you can plant datura in Great 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 really do well. 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

On average the last frost is on May 15 in Great Falls. In the coldest months of winter you should expect an average low temperature of -30°F.

Remember that USDA zone info for Great Falls is an average and the actual date of last frost can change quite a bit from year to year. Since half of the time in Great Falls you get a frost after May 15 be ready to cover your datura in the event of a late frost.

USDA Zone Info for Great Falls

Here is the info for USDA Zone 4a.

Average Date of Last Frost (spring)	May 15
Average Date of First Frost (fall)	September 15
Lowest Expected Low	-30°F
Highest Expected Low	-25°F

This means that on a really cold year, the coldest it will get is -30°F. On most years you should be prepared to experience lows near -25°F.

Plants to Grow in Great Falls

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