One of the first steps you take when you are figuring out 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.

By using the USDA zone info for Vandalia you should be able to estimate when it's a good idea to plant thunbergia.

Planting Calendar for Thunbergia

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

You can not plant thunbergia until after the last frost because they are not cold tolerant.

The earliest that you can plant thunbergia in Vandalia 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 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 grow to maturity. 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 Vandalia the average date of last frost happens on April 15. In the coldest months of winter you should expect an average low temperature of -10°F.

Since the USDA zone info for Vandalia is not always accurate the actual date of last frost is different every year. Half of the time in Vandalia there is a last frost after April 15 so make sure that you are prepared to protect your thunbergia if you have a late frost.

USDA Zone Info for Vandalia

Here is the info for USDA Zone 6a.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-10°F
Highest Expected Low	-5°F

This means that on a really cold year, the coldest it will get is -10°F. On most years you should be prepared to experience lows near -5°F.

Plants to Grow in Vandalia

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