One of the best tools that you have as gardeners to help us determine your gardening schedule is the 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.

In Riverdale you can estimate when you can plant thunbergia by referring to the USDA zone info.

Planting Calendar for Thunbergia

Frost tolerance for thunbergia:	Not tolerant of frost.
When to plant:	After all chance of 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 Riverdale 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 fully mature. Starting your thunbergia indoors is a great way to get them started a couple of weeks earlier.

Last Frost Date

On average the last frost has passed is on April 15 in Riverdale. You should expect an average low temperature of -10°F in the coldest months of winter.

Since the USDA zone info for Riverdale is not always accurate the actual date of last frost changes from year to year. Since half of the time in Riverdale you get a frost after April 15 be ready to protect your thunbergia in the event of a late frost.

USDA Zone Info for Riverdale

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 Riverdale

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