Before planting it is a good idea to find your USDA Zone info to figure out 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.

By checking out the USDA zone info for Aspen you should be able to figure out when it's possible to plant phlox.

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 a little earlier in the year because they are one of those plants that can tolerate a little bit of cold weather.

The earliest that you can plant phlox in Aspen is February. However, you really should wait until March if you don't want to take any chances.

The last month that you can plant phlox and expect a good harvest is probably September. Any later than that and your phlox may not have a chance to fully mature. You can get started a little bit earlier by starting your phlox indoors.

Last Frost Date

The average date of last frost is April 15 in Aspen. In the coldest months of winter you should expect an average low temperature of -15°F.

Always keep in mind that USDA zone info for Aspen is not always accurate and the actual date of last frost can change quite a bit from year to year. Half of the time in Aspen you get surprised by a frost after April 15 so make sure that you are ready to protect your phlox if you have one of those late frosts.

USDA Zone Info for Aspen

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 Aspen

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