Before planting it is a good idea to find your USDA Zone info to determine your garden schedule. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

In Caribou you can figure out when it's the best time to plant thunbergia by looking at the USDA zone info.

Planting Calendar for Thunbergia

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

Thunbergia do not do well in cold weather which tells us that you need to wait until it warms up after the last frost before you can plant them.

The earliest that you can plant thunbergia in Caribou 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 thunbergia and expect a good harvest is probably August. If you wait any later than that and your thunbergia may not have a chance to really do well. You can get started a few weeks earlier by starting your thunbergia indoors.

Last Frost Date

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

Always keep in mind that the actual date of last frost is not always accurate because it is based on the USDA zone info for Caribou and it will vary from year to year. Half of the time in Caribou you get surprised by a frost after May 15 so always be ready to cover your thunbergia if you have a late frost.

USDA Zone Info for Caribou

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 Caribou

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