One of the first steps you take when you are determining your gardening schedule is find your USDA Zone info. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

The earliest that you can plant thunbergia in Rolla should be determined 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.

It's a bad idea to plant thunbergia until after the last frost because they are not cold tolerant.

The earliest that you can plant thunbergia in Rolla 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 really do well. You can get started a couple of weeks earlier by starting your thunbergia indoors.

Last Frost Date

The average date of last frost is April 15 in Rolla. You can expect an average low temperature of -5°F in the coldest months of winter.

Keep in mind that the actual date of last frost may not be accurate from year to year because it is based on the USDA zone info for Rolla and it can change quite a bit from year to year. Since half of the time in Rolla you get a frost after April 15 be ready to cover your thunbergia if you have one of those late frosts.

USDA Zone Info for Rolla

Here is the info for USDA Zone 6b.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-5°F
Highest Expected Low	0°F

This means that on a really cold year, the coldest it will get is -5°F. On most years you should be prepared to experience lows near 0°F.

Plants to Grow in Rolla

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