One of the best tools that you have as gardeners to help us determine your gardening schedule is the USDA zone info. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

The USDA zone info for Napa should be read to determine when to plant black radish.

Planting Calendar for Black radish

Frost tolerance for black radish:	Tolerant of some frost.
When to plant:	Up to 5 weeks before last frost.

Black radish do well in moderate cold which means that you can plant them earlier than plants that are more sensitive to the cold.

The earliest that you can plant black radish 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 black radish and expect a good harvest is probably October. If you wait any later than that and your black radish may not have a chance to really do well. You can get started a few weeks earlier by starting your black radish indoors.

Last Frost Date

On average the last frost when the weather gets warmer is on February 15 in Napa. It might get as low as 25°F during the coldest months of winter.

Since the USDA zone info for Napa is just an average the actual date of last frost can change quite a bit from year to year. Half of the time in Napa you get a frost after February 15 so just be sure to be ready to cover your black radish in the event of a late frost.

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.