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

By checking out the USDA zone info for Crystal Lake you should be able to estimate when it's possible to plant thunbergia.

Planting Calendar for Thunbergia

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

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

The earliest that you can plant thunbergia in Crystal Lake 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. If you wait any later than that and your thunbergia may not have a chance to really do well. 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 April 15 in Crystal Lake. In the coldest months of winter you can expect an average low temperature of -15°F.

Since the USDA zone info for Crystal Lake is an average the actual date of last frost can change quite a bit from year to year. Since half of the time in Crystal Lake you get a frost after April 15 be ready to protect your thunbergia in the event of a late frost.

USDA Zone Info for Crystal Lake

Here is the info for USDA Zone 5b.

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

This means that on a really cold year, the coldest it will get is -15°F. On most years you should be prepared to experience lows near -10°F.

Plants to Grow in Crystal Lake

You may be interested in your other planting guides for Crystal Lake.