The USDA Zone info is a great tool for gardeners to help us estimate your gardening schedule. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

One way of determining when to plant saxifraga is to examine the USDA zone info for Caribou.

Planting Calendar for Saxifraga

Frost tolerance for saxifraga:	Tolerant of a very small amount of frost.
When to plant:	Up to 3 weeks before last frost.

Saxifraga are barely cold tolerant which tells us that you can start planting them slightly earlier than other frost tender plants.

The earliest that you can plant saxifraga in Caribou is April. However, you really should wait until May if you don't want to take any chances.

The last month that you can plant saxifraga and expect a good harvest is probably August. If you wait any later than that and your saxifraga may not have a chance to really do well. If you are starting your saxifraga 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.

Since the USDA zone info for Caribou is an average the actual date of last frost can change quite a bit from year to year. Since half of the time in Caribou there is a last frost after May 15 be ready to protect your saxifraga 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.