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.

A common way of figuring out when it's a good idea to plant tall phlox is to examine the USDA zone info for Sioux City.

Planting Calendar for Tall Phlox

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

Tall Phlox are one of those plants that can tolerate a little bit of cold weather which means that you can get them planted earlier than other plants that might not handle the cold.

The earliest that you can plant tall phlox in Sioux City 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 tall phlox and expect a good harvest is probably September. Any later than that and your tall phlox may not have a chance to fully mature. Starting your tall phlox indoors is a great way to get them started a little bit earlier.

Last Frost Date

In Sioux City the average date of last frost happens on April 15. It might get as low as -20°F during the coldest months of winter.

It's important to remember that USDA zone info for Sioux City is just an average and the actual date of last frost will vary from year to year. Half of the time in Sioux City there is a last frost after April 15 so always be ready to cover your tall phlox if you have a surprise late frost.

USDA Zone Info for Sioux City

Here is the info for USDA Zone 5a.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-20°F
Highest Expected Low	-15°F

This means that on a really cold year, the coldest it will get is -20°F. On most years you should be prepared to experience lows near -15°F.

Plants to Grow in Sioux City

You may be interested in your other planting guides for Sioux City.