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 USDA zone info for Alvin can be reffered to in order to figure out when it's possible 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 really shouldn't plant periwinkles until after the last frost because they require warm weather.

The earliest that you can plant periwinkles in Alvin 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 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 Alvin the average date of last frost happens on February 15. You should expect an average low temperature of 20°F in the coldest months of winter.

It's important to remember that USDA zone info for Alvin is not always accurate and the actual date of last frost is different every year. Since half of the time in Alvin there is a last frost after February 15 be ready to protect your periwinkles in the event of one of those late frosts.

USDA Zone Info for Alvin

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 Alvin

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