The USDA Zone info is a great tool for gardeners to help us determine your gardening schedule. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

The earliest that you can plant periwinkles in Sullivan can be estimated by using the USDA zone info.

Planting Calendar for Periwinkles

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

It's probably not a good idea to plant periwinkles until after the last frost when the weather gets warmer because they do not do well in cold weather.

The earliest that you can plant periwinkles in Sullivan 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. 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 couple of weeks earlier.

Last Frost Date

The average date of last frost is April 15 in Sullivan. It might get as low as 5°F during the coldest months of winter.

Since the USDA zone info for Sullivan may not be accurate from year to year the actual date of last frost can change quite a bit from year to year. Since half of the time in Sullivan last frost occurs after April 15 be ready to protect your periwinkles in the event of one of those late frosts.

USDA Zone Info for Sullivan

Here is the info for USDA Zone 7b.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	5°F
Highest Expected Low	10°F

This means that on a really cold year, the coldest it will get is 5°F. On most years you should be prepared to experience lows near 10°F.

Plants to Grow in Sullivan

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