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

You should be able to estimate when you can plant napa cabbage by referring to the USDA zone info for Rock Springs.

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 plant them much earlier than plants that are more sensitive to the cold.

The earliest that you can plant napa cabbage in Rock Springs 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. You probably don't want to wait any later than that or else 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

The average date of last frost is April 15 in Rock Springs. In the coldest months of winter you can expect an average low temperature of -20°F.

Since the USDA zone info for Rock Springs is just an average the actual date of last frost can change quite a bit from year to year. Since half of the time in Rock Springs it frosts late in the year after April 15 be ready to protect your napa cabbage if you have one of those late frosts.

USDA Zone Info for Rock Springs

Here is the info for USDA Zone 5a.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-20°F
Highest Expected Low	-15°F

This means that on a really cold year, the coldest it will get is -20°F. On most years you should be prepared to experience lows near -15°F.

Plants to Grow in Rock Springs

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