The USDA Zone info is a great tool for gardeners to help us determine your gardening schedule. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

One way of determining when it's possible to plant periwinkles is to look at the USDA zone info for Sullivan City.

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 has passed because they are not cold tolerant.

The earliest that you can plant periwinkles in Sullivan City 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. If you are starting your periwinkles indoors then you might be able to get away with starting them a little bit earlier.

Last Frost Date

In Sullivan City the average date of last frost happens on February 15. In the coldest months of winter you can expect an average low temperature of 25°F.

Since the USDA zone info for Sullivan City may not be accurate from year to year the actual date of last frost changes from year to year. Since half of the time in Sullivan City there is a last frost after February 15 be ready to cover your periwinkles in the event of a late frost.

USDA Zone Info for Sullivan City

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 Sullivan City

You may be interested in your other planting guides for Sullivan City.