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.

The USDA zone info for Lake Oswego should be used to estimate when it's the best time to plant periwinkles.

Planting Calendar for Periwinkles

Frost tolerance for periwinkles:	Not tolerant of frost.
When to plant:	After the last frost.

You can not plant periwinkles until after the last frost because they require warm weather.

The earliest that you can plant periwinkles in Lake Oswego 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 periwinkles and expect a good harvest is probably August. If you wait any later than that and your periwinkles may not have a chance to really do well. Starting your periwinkles 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 Lake Oswego. In the coldest months of winter you can expect an average low temperature of 15°F.

Since the USDA zone info for Lake Oswego is not always accurate the actual date of last frost changes from year to year. Half of the time in Lake Oswego you get a frost after March 15 so make sure that you are ready to cover your periwinkles in the event of a late frost.

USDA Zone Info for Lake Oswego

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 Lake Oswego

You may be interested in your other planting guides for Lake Oswego.