The USDA Zone info is a great tool for gardeners to help us determine your gardening schedule. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

The first chance to plant canna in Thornton should be determined by checking out the USDA zone info.

Planting Calendar for Canna

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

Since canna require warm weather you have to wait until after the last frost before you can plant them.

The earliest that you can plant canna in Thornton 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 canna and expect a good harvest is probably August. Any later than that and your canna may not have a chance to fully mature. You can get started a little bit earlier by starting your canna indoors.

Last Frost Date

On average the last frost when the weather gets warmer is on April 15 in Thornton. You should expect an average low temperature of -15°F in the coldest months of winter.

Keep in mind that USDA zone info for Thornton is not always accurate and the actual date of last frost can change quite a bit from year to year. Half of the time in Thornton there is a last frost after April 15 so always be ready to cover your canna if you have one of those late frosts.

USDA Zone Info for Thornton

Here is the info for USDA Zone 5b.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-15°F
Highest Expected Low	-10°F

This means that on a really cold year, the coldest it will get is -15°F. On most years you should be prepared to experience lows near -10°F.

Plants to Grow in Thornton

You may be interested in your other planting guides for Thornton.