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.

It's possible to figure out when it's possible to plant tropical hibiscus by looking at the USDA zone info for Caribou.

Planting Calendar for Tropical Hibiscus

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

It's a bad idea to plant tropical hibiscus until after all chance of frost has passed because they require warm weather.

The earliest that you can plant tropical hibiscus 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 tropical hibiscus and expect a good harvest is probably August. Any later than that and your tropical hibiscus may not have a chance to grow to maturity. Starting your tropical hibiscus indoors is a great way to get them started a little bit earlier.

Last Frost Date

On average the last frost is on May 15 in Caribou. It might get as low as -30°F during the coldest months of winter.

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