The USDA Zone info is a great tool for gardeners to help us figure out your gardening schedule. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

The USDA zone info for Phoenix should be used to determine when you can plant liatris.

Planting Calendar for Liatris

Frost tolerance for liatris:	Very tolerant of frost.
When to plant:	Up to 7 weeks before last frost.

You can plant liatris earlier in the year because they are one of those plants that can tolerate quite a bit of cold weather.

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

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

Last Frost Date

On average the last frost is on February 15 in Phoenix. You can expect an average low temperature of 25°F in the coldest months of winter.

Keep in mind that the actual date of last frost is just an average because it is based on the USDA zone info for Phoenix and it can change quite a bit from year to year. Since half of the time in Phoenix you get a frost after February 15 be ready to protect your liatris in the event of a surprise late frost.

USDA Zone Info for Phoenix

Here is the info for USDA Zone 9b.

Average Date of Last Frost (spring)	February 15
Average Date of First Frost (fall)	December 15
Lowest Expected Low	25°F
Highest Expected Low	30°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 30°F.

Plants to Grow in Phoenix

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