One of the best tools that you have as gardeners to help us figure out 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.

The USDA zone info for Grand Rapids can be read to determine 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 when the weather gets warmer.

You should not plant thunbergia until after the last frost has passed because they are not cold tolerant.

The earliest that you can plant thunbergia in Grand Rapids 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. You probably don't want to wait any later than that or else your thunbergia may not have a chance to grow to maturity. You can get started a little bit earlier by starting your thunbergia indoors.

Last Frost Date

The average date of last frost is May 15 in Grand Rapids. It might get as low as -35°F during the coldest months of winter.

Remember that the actual date of last frost is an average because it is based on the USDA zone info for Grand Rapids and it changes from year to year. Half of the time in Grand Rapids there is a last frost after May 15 so just be sure to be ready to cover your thunbergia if you have a late frost.

USDA Zone Info for Grand Rapids

Here is the info for USDA Zone 3b.

Average Date of Last Frost (spring)	May 15
Average Date of First Frost (fall)	September 15
Lowest Expected Low	-35°F
Highest Expected Low	-30°F

This means that on a really cold year, the coldest it will get is -35°F. On most years you should be prepared to experience lows near -30°F.

Plants to Grow in Grand Rapids

You may be interested in your other planting guides for Grand Rapids.