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

The first opportunity to plant watercress in Denver should be figured out by using 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.

Watercress tend to make it in very little cold which means 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 Denver 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. If you wait 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 little bit earlier.

Last Frost Date

In Denver the average date of last frost happens on April 15. In the coldest months of winter you can expect an average low temperature of -15°F.

Since the USDA zone info for Denver is just an average the actual date of last frost can change quite a bit from year to year. Since half of the time in Denver you get surprised by a frost after April 15 be ready to cover your watercress in the event of one of those late frosts.

USDA Zone Info for Denver

Here is the info for USDA Zone 5b.

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

This means that on a really cold year, the coldest it will get is -15°F. On most years you should be prepared to experience lows near -10°F.

Plants to Grow in Denver

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