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.

By referring to the USDA zone info for Williston it's a good idea to figure out when it's a good idea to plant iresene.

Planting Calendar for Iresene

Frost tolerance for iresene:	Not tolerant of frost.
When to plant:	After the last frost.

Since iresene are not cold tolerant you must wait until after the last frost before you can plant them.

The earliest that you can plant iresene 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 iresene and expect a good harvest is probably August. You probably don't want to wait any later than that or else your iresene may not have a chance to really do well. If you are starting your iresene indoors then you might be able to get away with starting them a little bit earlier.

Last Frost Date

On average the last frost has passed is on May 15 in Williston. In the coldest months of winter you can expect an average low temperature of -30°F.

Just be sure to remember that the actual date of last frost is an average because it is based on the USDA zone info for Williston and it can change quite a bit from year to year. Half of the time in Williston last frost occurs after May 15 so make sure that you are prepared to protect your iresene 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.