Before planting it is a good idea to find your USDA Zone info to determine your garden schedule. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

One way of estimating when to plant napa cabbage is to refer to the USDA zone info for Ottumwa.

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 tells us that you can get them planted much earlier than other frost tender plants.

The earliest that you can plant napa cabbage in Ottumwa 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. 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 few weeks earlier.

Last Frost Date

In Ottumwa the average date of last frost happens on April 15. You should expect an average low temperature of -15°F in the coldest months of winter.

Since the USDA zone info for Ottumwa is just an average the actual date of last frost is different every year. Since half of the time in Ottumwa you get a frost after April 15 be ready to protect your napa cabbage in the event of a surprise late frost.

USDA Zone Info for Ottumwa

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 Ottumwa

You may be interested in your other planting guides for Ottumwa.