One of the first steps you take when you are getting a good idea your gardening schedule is find your USDA Zone info. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

The USDA zone info for Sulphur can be reffered to in order to estimate when it's a good idea 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.

You can not plant periwinkles until after the last frost when the weather gets warmer because they are not cold tolerant.

The earliest that you can plant periwinkles in Sulphur 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 fully mature. If you are starting your periwinkles indoors then you might be able to get away with starting them a few weeks earlier.

Last Frost Date

In Sulphur the average date of last frost happens on February 15. In the coldest months of winter you can expect an average low temperature of 20°F.

Always keep in mind that USDA zone info for Sulphur is just an average and the actual date of last frost can change quite a bit from year to year. Half of the time in Sulphur last frost occurs after February 15 so make sure that you are ready to cover your periwinkles if you have a late frost.

USDA Zone Info for Sulphur

Here is the info for USDA Zone 9a.

Average Date of Last Frost (spring)	February 15
Average Date of First Frost (fall)	December 15
Lowest Expected Low	20°F
Highest Expected Low	25°F

This means that on a really cold year, the coldest it will get is 20°F. On most years you should be prepared to experience lows near 25°F.

Plants to Grow in Sulphur

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