One of the first steps you take when you are getting a good idea your gardening schedule is find your 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.

It's possible to figure out when it's the best time to plant napa cabbage by referring to the USDA zone info for Umatilla.

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 tells us that you can start planting them much earlier than plants that are more sensitive to the cold.

The earliest that you can plant napa cabbage in Umatilla 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 fully mature. 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 April 15 in Umatilla. You can expect an average low temperature of 5°F in the coldest months of winter.

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

USDA Zone Info for Umatilla

Here is the info for USDA Zone 7b.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	5°F
Highest Expected Low	10°F

This means that on a really cold year, the coldest it will get is 5°F. On most years you should be prepared to experience lows near 10°F.

Plants to Grow in Umatilla

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