Before planting it is a good idea to find your USDA Zone info to determine your garden schedule. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

A way of determining when to plant trailing portulaca is to examine the USDA zone info for Watertown.

Planting Calendar for Trailing Portulaca

Frost tolerance for trailing portulaca:	Not tolerant of frost.
When to plant:	After the last frost when the weather gets warmer.

It's probably a bad idea to plant trailing portulaca until after all chance of frost has passed because they require warm weather.

The earliest that you can plant trailing portulaca in Watertown is May. However, you really should wait until June if you don't want to take any chances.

The last month that you can plant trailing portulaca and expect a good harvest is probably August. You probably don't want to wait any later than that or else your trailing portulaca may not have a chance to really do well. Starting your trailing portulaca indoors is a great way to get them started a little bit earlier.

Last Frost Date

On average the last frost has passed is on May 15 in Watertown. In the coldest months of winter you should expect an average low temperature of -30°F.

Since the USDA zone info for Watertown is an average the actual date of last frost is different every year. Since half of the time in Watertown you get surprised by a frost after May 15 be ready to protect your trailing portulaca in the event of one of those late frosts.

USDA Zone Info for Watertown

Here is the info for USDA Zone 4a.

Average Date of Last Frost (spring)	May 15
Average Date of First Frost (fall)	September 15
Lowest Expected Low	-30°F
Highest Expected Low	-25°F

This means that on a really cold year, the coldest it will get is -30°F. On most years you should be prepared to experience lows near -25°F.

Plants to Grow in Watertown

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