One of the best tools that you have as gardeners to help us determine your gardening schedule is the USDA zone info. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

The earliest that you can plant thunbergia in Walla Walla can be determined by checking out 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.

Since thunbergia require warm weather it's necessary to wait until after the last frost has passed before you can plant them.

The earliest that you can plant thunbergia in Walla Walla 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. Any later than that and your thunbergia may not have a chance to fully mature. You can get started a little bit earlier by starting your thunbergia indoors.

Last Frost Date

On average the last frost when the weather gets warmer is on April 15 in Walla Walla. You should expect an average low temperature of 0°F in the coldest months of winter.

Since the USDA zone info for Walla Walla is an average the actual date of last frost can change quite a bit from year to year. Half of the time in Walla Walla it frosts late in the year after April 15 so always be ready to cover your thunbergia if you have a late frost.

USDA Zone Info for Walla Walla

Here is the info for USDA Zone 7a.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	0°F
Highest Expected Low	5°F

This means that on a really cold year, the coldest it will get is 0°F. On most years you should be prepared to experience lows near 5°F.

Plants to Grow in Walla Walla

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