One of the first steps you take when you are determining 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 common way of estimating when it's the best time to plant canna is to use the USDA zone info for Great Falls.

Planting Calendar for Canna

Frost tolerance for canna:	Not tolerant of frost.
When to plant:	After the last frost.

It's probably not a good idea to plant canna until after the last frost when the weather gets warmer because they are not cold tolerant.

The earliest that you can plant canna in Great Falls is May. However, you really should wait until June if you don't want to take any chances.

The last month that you can plant canna and expect a good harvest is probably August. If you wait any later than that and your canna may not have a chance to fully mature. If you are starting your canna indoors then you might be able to get away with starting them a little bit earlier.

Last Frost Date

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

Since the USDA zone info for Great Falls is not always accurate the actual date of last frost changes from year to year. Half of the time in Great Falls it frosts late in the year after May 15 so always be ready to protect your canna if you have a surprise 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.