One of the first steps you take when you are determining your gardening schedule is find your USDA Zone info. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

A way of determining when to plant phlox is to use the USDA zone info for Riverton.

Planting Calendar for Phlox

Frost tolerance for phlox:	Tolerant of some frost.
When to plant:	Up to 5 weeks before last frost.

You can plant phlox just a bit earlier in the year because they are moderately cold tolerant.

The earliest that you can plant phlox in Riverton 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 phlox and expect a good harvest is probably August. Any later than that and your phlox may not have a chance to fully mature. If you are starting your phlox indoors then you might be able to get away with starting them a couple of weeks earlier.

Last Frost Date

In Riverton the average date of last frost happens on May 15. You should expect an average low temperature of -25°F in the coldest months of winter.

Just be sure to remember that the actual date of last frost is just an average because it is based on the USDA zone info for Riverton and it is different every year. Since half of the time in Riverton you get surprised by a frost after May 15 be ready to cover your phlox if you have a surprise late frost.

USDA Zone Info for Riverton

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 Riverton

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