Before planting it is a good idea to find your USDA Zone info to determine your garden schedule. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

The first opportunity to plant anchusa in Caribou should be figured out by checking out the USDA zone info.

Planting Calendar for Anchusa

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

Since anchusa are very cold tolerant you can plant them much earlier in the year than other frost tender plants.

The earliest that you can plant anchusa in Caribou 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 anchusa and expect a good harvest is probably August. If you wait any later than that and your anchusa may not have a chance to really do well. You can get started a couple of weeks earlier by starting your anchusa indoors.

Last Frost Date

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

It's important to remember that USDA zone info for Caribou may not be accurate from year to year and 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 be sure to be ready to protect your anchusa in the event of one of those late frosts.

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.