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

By reviewing the USDA zone info for Sulphur you will be able to estimate when to plant periwinkles.

Planting Calendar for Periwinkles

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

Periwinkles do not do well in cold weather which tells us that it's important to wait until it warms up after the last frost has passed before you can plant them.

The earliest that you can plant periwinkles in Sulphur 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 fully mature. 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 Sulphur the average date of last frost happens on April 15. You can expect an average low temperature of 5°F in the coldest months of winter.

Since the USDA zone info for Sulphur may not be accurate from year to year the actual date of last frost is different every year. Since half of the time in Sulphur there is a last frost after April 15 be ready to cover your periwinkles if you have one of those late frosts.

USDA Zone Info for Sulphur

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 Sulphur

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