The USDA Zone info is a great tool for gardeners to help us estimate your gardening schedule. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

You can estimate when to plant watercress in San Ramon by reviewing the USDA zone info.

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.

Since watercress are barely cold tolerant you can plant them a bit earlier in the year than more sensitive plants.

The earliest that you can plant watercress in San Ramon 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. Any later than that and your watercress may not have a chance to fully mature. Starting your watercress indoors is a great way to get them started a little bit earlier.

Last Frost Date

In San Ramon the average date of last frost happens on February 15. In the coldest months of winter you should expect an average low temperature of 25°F.

Since the USDA zone info for San Ramon is not always accurate the actual date of last frost can change quite a bit from year to year. Since half of the time in San Ramon you get a frost after February 15 be ready to protect your watercress in the event of one of those late frosts.

USDA Zone Info for San Ramon

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 San Ramon

You may be interested in your other planting guides for San Ramon.