One of the first steps you take when you are getting a good idea 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.

It's possible to estimate when it's a good idea to plant thunbergia by referring to the USDA zone info for Stillwater.

Planting Calendar for Thunbergia

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

You should not plant thunbergia until after all chance of frost has passed because they require warm weather.

The earliest that you can plant thunbergia in Stillwater 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. Any later than that and 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

In Stillwater the average date of last frost happens on May 15. You should expect an average low temperature of -25°F in the coldest months of winter.

Remember that USDA zone info for Stillwater is not always accurate and the actual date of last frost can change quite a bit from year to year. Half of the time in Stillwater you get a frost after May 15 so always be ready to protect your thunbergia if you have a surprise late frost.

USDA Zone Info for Stillwater

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 Stillwater

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