The USDA Zone info is a great tool for gardeners to help us estimate 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.

A way of estimating when to plant watercress is to use the USDA zone info for Rohnert Park.

Planting Calendar for Watercress

Frost tolerance for watercress:	Tolerant of a very small amount of frost.
When to plant:	Up to 3 weeks before last frost.

Watercress are one of those plants that can tolerate a tiny bit of cold weather which tells us that you can plant them slightly earlier than other plants that might not handle the cold.

The earliest that you can plant watercress in Rohnert Park 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 watercress and expect a good harvest is probably September. You probably don't want to wait any later than that or else your watercress may not have a chance to fully mature. If you are starting your watercress indoors then you might be able to get away with starting them a little bit earlier.

Last Frost Date

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

Since the USDA zone info for Rohnert Park is an average the actual date of last frost changes from year to year. Half of the time in Rohnert Park there is a last frost after February 15 so make sure that you are ready to cover your watercress in the event of a surprise late frost.

USDA Zone Info for Rohnert Park

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 Rohnert Park

You may be interested in your other planting guides for Rohnert Park.