One of the best tools that you have as gardeners to help us figure out your gardening schedule is the USDA zone info. 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 Arnold should be reffered to in order to estimate 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 ok in mild cold which tells us that you can plant them just a tiny bit earlier in the year than more sensitive plants.

The earliest that you can plant watercress in Arnold 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 grow to maturity. If you are starting your watercress indoors then you might be able to get away with starting them a couple of weeks earlier.

Last Frost Date

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

Always keep in mind that USDA zone info for Arnold may not be accurate from year to year and the actual date of last frost can change quite a bit from year to year. Half of the time in Arnold there is a last frost after April 15 so just be sure to be ready to cover your watercress in the event of one of those late frosts.

USDA Zone Info for Arnold

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 Arnold

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