The USDA Zone info is a great tool for gardeners to help us determine your gardening schedule. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

In Napa you can estimate when it's the best time to plant four o' clock by using the USDA zone info.

Planting Calendar for Four O' Clock

Frost tolerance for four o' clock:	Not tolerant of frost.
When to plant:	After the last frost.

Since four o' clock require warm weather you really should wait until after the last frost when the weather gets warmer before you can plant them.

The earliest that you can plant four o' clock in Napa is March. However, you really should wait until April if you don't want to take any chances.

The last month that you can plant four o' clock and expect a good harvest is probably September. You probably don't want to wait any later than that or else your four o' clock may not have a chance to grow to maturity. If you are starting your four o' clock indoors then you might be able to get away with starting them a little bit earlier.

Last Frost Date

In Napa the average date of last frost happens on February 15. It might get as low as 25°F during the coldest months of winter.

Just be sure to remember that the actual date of last frost is not always accurate because it is based on the USDA zone info for Napa and it will vary from year to year. Half of the time in Napa it frosts late in the year after February 15 so just be sure to be ready to cover your four o' clock 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.