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.

It's possible to estimate when you can plant periwinkles by checking out the USDA zone info for Stillwater.

Planting Calendar for Periwinkles

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

It's probably a bad idea to plant periwinkles until after the last frost because they are not cold tolerant.

The earliest that you can plant periwinkles in Stillwater 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. You probably don't want to wait any later than that or else your periwinkles may not have a chance to grow to maturity. 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 April 15 in Stillwater. In the coldest months of winter you should expect an average low temperature of 0°F.

Just be sure to remember that the actual date of last frost is an average because it is based on the USDA zone info for Stillwater and it can change quite a bit from year to year. Half of the time in Stillwater you get surprised by a frost after April 15 so make sure that you are ready to protect your periwinkles if you have one of those late frosts.

USDA Zone Info for Stillwater

Here is the info for USDA Zone 7a.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	0°F
Highest Expected Low	5°F

This means that on a really cold year, the coldest it will get is 0°F. On most years you should be prepared to experience lows near 5°F.

Plants to Grow in Stillwater

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