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.

You should be able to figure out when to plant diascia by looking at the USDA zone info for Tualatin.

Planting Calendar for Diascia

Frost tolerance for diascia:	Tolerant of some frost.
When to plant:	Up to 5 weeks before last frost.

Diascia do well in moderate cold which means that you can plant them earlier than other frost tender plants.

The earliest that you can plant diascia in Tualatin is February. However, you really should wait until March if you don't want to take any chances.

The last month that you can plant diascia and expect a good harvest is probably September. Any later than that and your diascia may not have a chance to fully mature. Starting your diascia indoors is a great way to get them started a little bit earlier.

Last Frost Date

The average date of last frost is March 15 in Tualatin. It might get as low as 15°F during the coldest months of winter.

Since the USDA zone info for Tualatin may not be accurate from year to year the actual date of last frost will vary from year to year. Since half of the time in Tualatin last frost occurs after March 15 be ready to protect your diascia in the event of one of those late frosts.

USDA Zone Info for Tualatin

Here is the info for USDA Zone 8b.

Average Date of Last Frost (spring)	March 15
Average Date of First Frost (fall)	November 15
Lowest Expected Low	15°F
Highest Expected Low	20°F

This means that on a really cold year, the coldest it will get is 15°F. On most years you should be prepared to experience lows near 20°F.

Plants to Grow in Tualatin

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