The USDA Zone info is a great tool for gardeners to help us determine your gardening schedule. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

You should be able to estimate when it's a good idea to plant hibiscus by reviewing the USDA zone info for Zone 4b.

Planting Calendar for Hibiscus

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

Hibiscus are not cold tolerant which means that you need to wait until it warms up after the last frost before you can plant them.

The earliest that you can plant hibiscus in Zone 4b 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 hibiscus and expect a good harvest is probably August. You probably don't want to wait any later than that or else your hibiscus may not have a chance to grow to maturity. If you are starting your hibiscus indoors then you might be able to get away with starting them a little bit earlier.

Last Frost Date

On average the last frost has passed is on May 15 in Zone 4b. In the coldest months of winter you can expect an average low temperature of -25°F.

Since the USDA zone info for Zone 4b is not always accurate the actual date of last frost will vary from year to year. Half of the time in Zone 4b you get surprised by a frost after May 15 so always be ready to cover your hibiscus if you have a late frost.

USDA Zone Info for Zone 4b

Here is the info for USDA Zone 4b.

Average Date of Last Frost (spring)	May 15
Average Date of First Frost (fall)	September 15
Lowest Expected Low	-25°F
Highest Expected Low	-20°F

This means that on a really cold year, the coldest it will get is -25°F. On most years you should be prepared to experience lows near -20°F.

Plants to Grow in Zone 4b

You may be interested in your other planting guides for Zone 4b.