Before planting it is a good idea to find your USDA Zone info to determine your garden schedule. 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 to plant thunbergia by referring to the USDA zone info for Howell.

Planting Calendar for Thunbergia

Frost tolerance for thunbergia:	Not tolerant of frost.
When to plant:	After the last frost when the weather gets warmer.

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

The earliest that you can plant thunbergia in Howell 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 few weeks earlier by starting your thunbergia indoors.

Last Frost Date

The average date of last frost is April 15 in Howell. You can expect an average low temperature of -10°F in the coldest months of winter.

Just be sure to remember that the actual date of last frost is just an average because it is based on the USDA zone info for Howell and it is different every year. Since half of the time in Howell there is a last frost after April 15 be ready to cover your thunbergia if you have a surprise late frost.

USDA Zone Info for Howell

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 Howell

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