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.

In Washington you can estimate when it's a good idea to 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.

Thunbergia require warm weather which means that it is necessary to wait until it warms up after the last frost before you can plant them.

The earliest that you can plant thunbergia in Washington 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. You can get started a few weeks earlier by starting your thunbergia indoors.

Last Frost Date

On average the last frost when the weather gets warmer is on April 15 in Washington. In the coldest months of winter you should expect an average low temperature of -10°F.

Always keep in mind that USDA zone info for Washington 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 Washington last frost occurs after April 15 so be sure to be ready to cover your thunbergia in the event of a late frost.

USDA Zone Info for Washington

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 Washington

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