One of the first steps you take when you are making a decision about your gardening schedule is find your USDA Zone info. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

The earliest that you can plant thunbergia in Zone 2b can be estimated by referring to the USDA zone info.

Planting Calendar for Thunbergia

Frost tolerance for thunbergia:	Not tolerant of frost.
When to plant:	After the last frost when the weather gets warmer.

Since thunbergia do not do well in cold weather you need to wait until after the last frost when the weather gets warmer before you can plant them.

The earliest that you can plant thunbergia in Zone 2b 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. You probably don't want to wait any later than that or else your thunbergia may not have a chance to fully mature. If you are starting your thunbergia indoors then you might be able to get away with starting them a couple of weeks earlier.

Last Frost Date

In Zone 2b the average date of last frost happens on May 15. It might get as low as -45°F during the coldest months of winter.

Since the USDA zone info for Zone 2b is just an average the actual date of last frost will vary from year to year. Since half of the time in Zone 2b there is a last frost after May 15 be ready to protect your thunbergia in the event of a surprise late frost.

USDA Zone Info for Zone 2b

Here is the info for USDA Zone 2b.

Average Date of Last Frost (spring)	May 15
Average Date of First Frost (fall)	August 15
Lowest Expected Low	-45°F
Highest Expected Low	-40°F

This means that on a really cold year, the coldest it will get is -45°F. On most years you should be prepared to experience lows near -40°F.

Plants to Grow in Zone 2b

You may be interested in your other planting guides for Zone 2b.