The USDA Zone info is a great tool for gardeners to help us figure out 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.

The USDA zone info for Zone 4b should be read to figure out when you can plant chrysocephalum.

Planting Calendar for Chrysocephalum

Frost tolerance for chrysocephalum:	Not tolerant of frost.
When to plant:	After the last frost when the weather gets warmer.

Since chrysocephalum require warm weather 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 chrysocephalum 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 chrysocephalum and expect a good harvest is probably August. Any later than that and your chrysocephalum may not have a chance to fully mature. If you are starting your chrysocephalum indoors then you might be able to get away with starting them a few weeks earlier.

Last Frost Date

In Zone 4b the average date of last frost happens on May 15. You can expect an average low temperature of -25°F in the coldest months of winter.

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 last frost occurs after May 15 so make sure that you are ready to protect your chrysocephalum in the event of a surprise 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.