Before planting it is a good idea to find your USDA Zone info to figure out your garden schedule. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

By looking at the USDA zone info for Grafton you should be able to determine 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.

Since watercress do ok in moderate cold you can plant them slightly earlier in the year than other frost tender plants.

The earliest that you can plant watercress in Grafton is March. However, you really should wait until April if you don't want to take any chances.

The last month that you can plant watercress and expect a good harvest is probably August. Any later than that and your watercress may not have a chance to really do well. Starting your watercress indoors is a great way to get them started a few weeks earlier.

Last Frost Date

The average date of last frost is April 15 in Grafton. You can expect an average low temperature of -10°F in the coldest months of winter.

Just be sure to remember that the actual date of last frost may not be accurate from year to year because it is based on the USDA zone info for Grafton and it will vary from year to year. Half of the time in Grafton there is a last frost after April 15 so make sure that you are prepared to protect your watercress if you have one of those late frosts.

USDA Zone Info for Grafton

Here is the info for USDA Zone 6a.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-10°F
Highest Expected Low	-5°F

This means that on a really cold year, the coldest it will get is -10°F. On most years you should be prepared to experience lows near -5°F.

Plants to Grow in Grafton

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