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

You can figure out when it's possible to plant periwinkles in Riverbank by reviewing the USDA zone info.

Planting Calendar for Periwinkles

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

Periwinkles do not do well in cold weather which tells us that you must wait until it warms up after the last frost when the weather gets warmer before you can plant them.

The earliest that you can plant periwinkles in Riverbank 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. Any later than that and your periwinkles may not have a chance to grow to maturity. You can get started a little bit earlier by starting your periwinkles indoors.

Last Frost Date

In Riverbank 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.

Always keep in mind that USDA zone info for Riverbank is not always accurate and the actual date of last frost will vary from year to year. Half of the time in Riverbank there is a last frost after February 15 so just be sure to be ready to protect your periwinkles if you have one of those late frosts.

USDA Zone Info for Riverbank

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 Riverbank

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