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

By referring to the USDA zone info for Houston it's a good idea to determine when you can 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 do well in mild cold which tells us that you can plant them just a tiny bit earlier in the year than other frost tender plants.

The earliest that you can plant watercress in Houston 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 really do well. 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

On average the last frost when the weather gets warmer is on February 15 in Houston. You should expect an average low temperature of 20°F in the coldest months of winter.

Remember that USDA zone info for Houston may not be accurate from year to year and the actual date of last frost is different every year. Half of the time in Houston you get surprised by a frost after February 15 so be sure to be ready to protect your watercress if you have a surprise late frost.

USDA Zone Info for Houston

Here is the info for USDA Zone 9a.

Average Date of Last Frost (spring)	February 15
Average Date of First Frost (fall)	December 15
Lowest Expected Low	20°F
Highest Expected Low	25°F

This means that on a really cold year, the coldest it will get is 20°F. On most years you should be prepared to experience lows near 25°F.

Plants to Grow in Houston

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