Before planting it is a good idea to find your USDA Zone info to figure out 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.

By looking at the USDA zone info for Ottawa it's a good idea to estimate 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 all chance of frost has passed.

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

The earliest that you can plant thunbergia in Ottawa 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 really do well. Starting your thunbergia indoors is a great way to get them started a little bit earlier.

Last Frost Date

On average all chance of frost has passed is on April 15 in Ottawa. You can expect an average low temperature of -10°F in the coldest months of winter.

Since the USDA zone info for Ottawa is just an average the actual date of last frost will vary from year to year. Half of the time in Ottawa you get surprised by a frost after April 15 so just be sure to be ready to protect your thunbergia if you have one of those late frosts.

USDA Zone Info for Ottawa

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 Ottawa

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