One of the first steps you take when you are figuring out your gardening schedule is find your USDA Zone info. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

A common way of estimating when it's the best time to plant portulaca is to examine the USDA zone info for River Falls.

Planting Calendar for Portulaca

Frost tolerance for portulaca:	Not tolerant of frost.
When to plant:	After the last frost has passed.

It's a bad idea to plant portulaca until after the last frost when the weather gets warmer because they are not cold tolerant.

The earliest that you can plant portulaca in River Falls 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 portulaca and expect a good harvest is probably August. If you wait any later than that and your portulaca may not have a chance to really do well. If you are starting your portulaca indoors then you might be able to get away with starting them a few weeks earlier.

Last Frost Date

On average the last frost is on May 15 in River Falls. You can expect an average low temperature of -25°F in the coldest months of winter.

It's important to remember that the actual date of last frost is not always accurate because it is based on the USDA zone info for River Falls and it will vary from year to year. Half of the time in River Falls last frost occurs after May 15 so be sure to be ready to protect your portulaca in the event of one of those late frosts.

USDA Zone Info for River Falls

Here is the info for USDA Zone 4b.

Average Date of Last Frost (spring)	May 15
Average Date of First Frost (fall)	September 15
Lowest Expected Low	-25°F
Highest Expected Low	-20°F

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

Plants to Grow in River Falls

You may be interested in your other planting guides for River Falls.