One of the best tools that you have as gardeners to help us estimate your gardening schedule is the USDA zone info. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

In Zone 4b you can estimate when it's possible to plant napa cabbage by referring to the USDA zone info.

Planting Calendar for Napa cabbage

Frost tolerance for napa cabbage:	Very tolerant of frost.
When to plant:	Up to 7 weeks before last frost.

Napa cabbage do well in cold which means that you can plant them much earlier than other plants that might not handle the cold.

The earliest that you can plant napa cabbage in Zone 4b is March. However, you really should wait until April if you don't want to take any chances.

The last month that you can plant napa cabbage and expect a good harvest is probably August. Any later than that and your napa cabbage may not have a chance to grow to maturity. Starting your napa cabbage indoors is a great way to get them started a couple of weeks earlier.

Last Frost Date

The average date of last frost is May 15 in Zone 4b. It might get as low as -25°F during the coldest months of winter.

Just be sure to remember that USDA zone info for Zone 4b is just an average and the actual date of last frost is different every year. Since half of the time in Zone 4b you get a frost after May 15 be ready to cover your napa cabbage in the event of 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.