The USDA Zone info is a great tool for gardeners to help us determine your gardening schedule. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

The USDA zone info for Caribou should be read to figure out when you can plant asparagus fern.

Planting Calendar for Asparagus Fern

Frost tolerance for asparagus fern:	Not tolerant of frost.
When to plant:	After the last frost has passed.

You should not plant asparagus fern until after the last frost because they require warm weather.

The earliest that you can plant asparagus fern in Caribou 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 asparagus fern and expect a good harvest is probably August. Any later than that and your asparagus fern may not have a chance to really do well. Starting your asparagus fern indoors is a great way to get them started a little bit earlier.

Last Frost Date

In Caribou the average date of last frost happens on May 15. In the coldest months of winter you can expect an average low temperature of -30°F.

Since the USDA zone info for Caribou is not always accurate the actual date of last frost will vary from year to year. Half of the time in Caribou you get a frost after May 15 so make sure that you are prepared to cover your asparagus fern if you have a late frost.

USDA Zone Info for Caribou

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 Caribou

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