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.

In Williston you can figure out when it's a good idea to plant alyssum by referring to the USDA zone info.

Planting Calendar for Alyssum

Frost tolerance for alyssum:	Very tolerant of frost.
When to plant:	Up to 7 weeks before last frost.

Alyssum do well in cold which means that you can get them planted much earlier than other plants that might not handle the cold.

The earliest that you can plant alyssum in Williston 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 alyssum and expect a good harvest is probably August. If you wait any later than that and your alyssum may not have a chance to grow to maturity. Starting your alyssum indoors is a great way to get them started a few weeks earlier.

Last Frost Date

On average the last frost is on 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. Half of the time in Williston there is a last frost after May 15 so make sure that you are prepared to cover your alyssum if you have a surprise 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.