One of the first steps you take when you are determining 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.

A way of determining when it's a good idea to plant rosemary is to check out the USDA zone info for Napa.

Planting Calendar for Rosemary

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

Rosemary can survive in quite a bit of cold which means that you can plant them a lot earlier in the year than other frost tender plants.

The earliest that you can plant rosemary in Napa is January. However, you really should wait until February if you don't want to take any chances.

The last month that you can plant rosemary and expect a good harvest is probably October. Any later than that and your rosemary may not have a chance to really do well. If you are starting your rosemary indoors then you might be able to get away with starting them a few weeks earlier.

Last Frost Date

In Napa the average date of last frost happens on February 15. You can expect an average low temperature of 25°F in the coldest months of winter.

Since the USDA zone info for Napa is not always accurate the actual date of last frost will vary from year to year. Since half of the time in Napa last frost occurs after February 15 be ready to cover your rosemary if you have one of those late frosts.

USDA Zone Info for Napa

Here is the info for USDA Zone 9b.

Average Date of Last Frost (spring)	February 15
Average Date of First Frost (fall)	December 15
Lowest Expected Low	25°F
Highest Expected Low	30°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 30°F.

Plants to Grow in Napa

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