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.

You should be able to estimate when it's the best time to plant napa valley fern by looking at the USDA zone info for Caribou.

Planting Calendar for Napa Valley Fern

Frost tolerance for napa valley fern:	Not tolerant of frost.
When to plant:	After the last frost.

You really shouldn't plant napa valley fern until after the last frost has passed because they do not do well in cold weather.

The earliest that you can plant napa valley 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 napa valley fern and expect a good harvest is probably August. You probably don't want to wait any later than that or else your napa valley fern may not have a chance to really do well. You can get started a few weeks earlier by starting your napa valley fern indoors.

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.

It's important to remember that the actual date of last frost may not be accurate from year to year because it is based on the USDA zone info for Caribou and it can change quite a bit from year to year. Half of the time in Caribou you get a frost after May 15 so always be ready to protect your napa valley fern if you have 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.