The USDA Zone info is a great tool for gardeners to help us figure out your gardening schedule. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

You can figure out when it's a good idea to plant tall phlox in Denver by looking at the USDA zone info.

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 tells us that you can plant them earlier than more sensitive plants.

The earliest that you can plant tall phlox in Denver 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. You probably don't want to wait any later than that or else your tall phlox may not have a chance to really do well. You can get started a couple of weeks earlier by starting your tall phlox indoors.

Last Frost Date

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

Since the USDA zone info for Denver is not always accurate the actual date of last frost can change quite a bit from year to year. Half of the time in Denver last frost occurs after April 15 so always be ready to protect your tall phlox if you have one of those late frosts.

USDA Zone Info for Denver

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 Denver

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