Before planting it is a good idea to find your USDA Zone info to determine your garden 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 Rock Island can be reviewed to figure out when it's the best time to plant napa cabbage.

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 are one of those plants that can tolerate quite a bit of cold weather which means that you can plant them a quite a bit earlier than other plants that might not handle the cold.

The earliest that you can plant napa cabbage in Rock Island is February. However, you really should wait until March 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 September. If you wait any later than that and your napa cabbage may not have a chance to fully mature. You can get started a couple of weeks earlier by starting your napa cabbage indoors.

Last Frost Date

The average date of last frost is April 15 in Rock Island. It might get as low as -15°F during the coldest months of winter.

Since the USDA zone info for Rock Island may not be accurate from year to year the actual date of last frost will vary from year to year. Half of the time in Rock Island it frosts late in the year after April 15 so make sure that you are ready to cover your napa cabbage if you have one of those late frosts.

USDA Zone Info for Rock Island

Here is the info for USDA Zone 5b.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-15°F
Highest Expected Low	-10°F

This means that on a really cold year, the coldest it will get is -15°F. On most years you should be prepared to experience lows near -10°F.

Plants to Grow in Rock Island

You may be interested in your other planting guides for Rock Island.