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 first opportunity to plant purple bell vines in Williston can be figured out by using the USDA zone info.

Planting Calendar for Purple Bell Vines

Frost tolerance for purple bell vines:	Tolerant of a very small amount of frost.
When to plant:	Up to 3 weeks before last frost.

Since purple bell vines are barely cold tolerant you can plant them just a tiny bit earlier in the year than other frost tender plants.

The earliest that you can plant purple bell vines in Williston 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 purple bell vines and expect a good harvest is probably August. Any later than that and your purple bell vines may not have a chance to grow to maturity. If you are starting your purple bell vines indoors then you might be able to get away with starting them a couple of weeks earlier.

Last Frost Date

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

Since the USDA zone info for Williston may not be accurate from year to year the actual date of last frost will vary from year to year. Half of the time in Williston there is a last frost after May 15 so always be ready to protect your purple bell vines if you have 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.