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.

A way of making a decision about when it's possible to plant anchusa is to refer to the USDA zone info for Great Falls.

Planting Calendar for Anchusa

Frost tolerance for anchusa:	Very tolerant of frost.
When to plant:	Up to 7 weeks before last frost.

Anchusa can survive in a bit of cold which means that you can plant them a lot earlier in the year than other plants that might not handle the cold.

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

Last Frost Date

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

Remember that USDA zone info for Great Falls may not be accurate from year to year and the actual date of last frost will vary from year to year. Since half of the time in Great Falls you get a frost after May 15 be ready to cover your anchusa if you have one of those late frosts.

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.