One of the first steps you take when you are making a decision about 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.

A way of determining when it's a good idea to plant osteospermum is to examine the USDA zone info for Tualatin.

Planting Calendar for Osteospermum

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

Since osteospermum are moderately cold tolerant you can plant them just a bit earlier in the year than more sensitive plants.

The earliest that you can plant osteospermum 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 osteospermum and expect a good harvest is probably September. Any later than that and your osteospermum may not have a chance to really do well. If you are starting your osteospermum indoors then you might be able to get away with starting them a few weeks earlier.

Last Frost Date

On average the last frost has passed is on March 15 in Tualatin. You can expect an average low temperature of 15°F in the coldest months of winter.

Keep in mind that the actual date of last frost is just an average because it is based on the USDA zone info for Tualatin and it will vary from year to year. Since half of the time in Tualatin there is a last frost after March 15 be ready to cover your osteospermum if you have 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.