One of the first steps you take when you are estimating your gardening schedule is find your USDA Zone info. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

The earliest that you can plant lithospermum in Caribou can be estimated by using the USDA zone info.

Planting Calendar for Lithospermum

Frost tolerance for lithospermum:	Not tolerant of frost.
When to plant:	After all chance of frost has passed.

Since lithospermum are not cold tolerant it's important to wait until after the last frost when the weather gets warmer before you can plant them.

The earliest that you can plant lithospermum 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 lithospermum and expect a good harvest is probably August. If you wait any later than that and your lithospermum may not have a chance to fully mature. If you are starting your lithospermum indoors then you might be able to get away with starting them a couple of weeks earlier.

Last Frost Date

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

Always keep in mind that USDA zone info for Caribou may not be accurate from year to year and the actual date of last frost is different every year. Half of the time in Caribou last frost occurs after May 15 so make sure that you are ready to cover your lithospermum in the event of a surprise 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.