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.

By reviewing the USDA zone info for Montpelier it's possible to estimate when to plant thunbergia.

Planting Calendar for Thunbergia

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

Since thunbergia are not cold tolerant it's necessary to wait until after all chance of frost has passed before you can plant them.

The earliest that you can plant thunbergia in Montpelier 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 few weeks earlier.

Last Frost Date

The average date of last frost is May 15 in Montpelier. In the coldest months of winter you can expect an average low temperature of -25°F.

Since the USDA zone info for Montpelier is an average the actual date of last frost will vary from year to year. Since half of the time in Montpelier it frosts late in the year after May 15 be ready to protect your thunbergia in the event of a late frost.

USDA Zone Info for Montpelier

Here is the info for USDA Zone 4b.

Average Date of Last Frost (spring)	May 15
Average Date of First Frost (fall)	September 15
Lowest Expected Low	-25°F
Highest Expected Low	-20°F

This means that on a really cold year, the coldest it will get is -25°F. On most years you should be prepared to experience lows near -20°F.

Plants to Grow in Montpelier

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