Before planting it is a good idea to find your USDA Zone info to determine your garden schedule. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

A common way of figuring out when to plant periwinkles is to examine the USDA zone info for Morro Bay.

Planting Calendar for Periwinkles

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

It's a bad idea to plant periwinkles until after the last frost because they require warm weather.

The earliest that you can plant periwinkles in Morro Bay is March. However, you really should wait until April if you don't want to take any chances.

The last month that you can plant periwinkles and expect a good harvest is probably September. 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 few weeks earlier.

Last Frost Date

In Morro Bay the average date of last frost happens on February 15. You should expect an average low temperature of 25°F in the coldest months of winter.

Since the USDA zone info for Morro Bay is an average the actual date of last frost changes from year to year. Since half of the time in Morro Bay you get a frost after February 15 be ready to cover your periwinkles if you have one of those late frosts.

USDA Zone Info for Morro Bay

Here is the info for USDA Zone 9b.

Average Date of Last Frost (spring)	February 15
Average Date of First Frost (fall)	December 15
Lowest Expected Low	25°F
Highest Expected Low	30°F

This means that on a really cold year, the coldest it will get is 25°F. On most years you should be prepared to experience lows near 30°F.

Plants to Grow in Morro Bay

You may be interested in your other planting guides for Morro Bay.