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

A way of estimating when it's the best time to plant periwinkles is to use the USDA zone info for Olympia.

Planting Calendar for Periwinkles

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

Since periwinkles are not cold tolerant you must wait until after the last frost has passed before you can plant them.

The earliest that you can plant periwinkles in Olympia 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 fully mature. If you are starting your periwinkles indoors then you might be able to get away with starting them a couple of weeks earlier.

Last Frost Date

On average the last frost has passed is on March 15 in Olympia. You should expect an average low temperature of 10°F in the coldest months of winter.

Remember that USDA zone info for Olympia is not always accurate and the actual date of last frost can change quite a bit from year to year. Half of the time in Olympia it frosts late in the year after March 15 so make sure that you are prepared to protect your periwinkles in the event of a surprise late frost.

USDA Zone Info for Olympia

Here is the info for USDA Zone 8a.

Average Date of Last Frost (spring)	March 15
Average Date of First Frost (fall)	November 15
Lowest Expected Low	10°F
Highest Expected Low	15°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 15°F.

Plants to Grow in Olympia

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