Before planting it is a good idea to find your USDA Zone info to estimate your garden schedule. 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 Mesa should be reviewed to figure out when it's the best time to plant watercress.

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 means that you can start planting them slightly earlier than other plants that might not handle the cold.

The earliest that you can plant watercress in Mesa 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. If you wait any later than that and your watercress may not have a chance to really do well. You can get started a few weeks earlier by starting your watercress indoors.

Last Frost Date

The average date of last frost is February 15 in Mesa. In the coldest months of winter you should expect an average low temperature of 25°F.

Since the USDA zone info for Mesa is just an average the actual date of last frost changes from year to year. Half of the time in Mesa last frost occurs after February 15 so just be sure to be ready to protect your watercress if you have a late frost.

USDA Zone Info for Mesa

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 Mesa

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