The USDA Zone info is a great tool for gardeners to help us figure out 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 Williston can be reffered to in order to determine when it's the best time to plant trailing portulaca.

Planting Calendar for Trailing Portulaca

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

Since trailing portulaca are not cold tolerant you really should wait until after the last frost has passed before you can plant them.

The earliest that you can plant trailing portulaca in Williston is May. However, you really should wait until June if you don't want to take any chances.

The last month that you can plant trailing portulaca and expect a good harvest is probably August. If you wait any later than that and your trailing portulaca may not have a chance to fully mature. You can get started a couple of weeks earlier by starting your trailing portulaca indoors.

Last Frost Date

The average date of last frost is May 15 in Williston. You should expect an average low temperature of -30°F in the coldest months of winter.

Since the USDA zone info for Williston is an average the actual date of last frost can change quite a bit from year to year. Since half of the time in Williston you get surprised by a frost after May 15 be ready to protect your trailing portulaca in the event of a late frost.

USDA Zone Info for Williston

Here is the info for USDA Zone 4a.

Average Date of Last Frost (spring)	May 15
Average Date of First Frost (fall)	September 15
Lowest Expected Low	-30°F
Highest Expected Low	-25°F

This means that on a really cold year, the coldest it will get is -30°F. On most years you should be prepared to experience lows near -25°F.

Plants to Grow in Williston

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