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

The USDA zone info for Denver should be read to estimate when it's the best time to plant peonies.

Planting Calendar for Peonies

Frost tolerance for peonies:	Tolerant of a very small amount of frost.
When to plant:	Up to 3 weeks before last frost.

Peonies do ok in moderate cold which tells us that you can get them planted just a bit earlier than plants that are more sensitive to the cold.

The earliest that you can plant peonies in Denver 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 peonies and expect a good harvest is probably August. You probably don't want to wait any later than that or else your peonies may not have a chance to fully mature. You can get started a couple of weeks earlier by starting your peonies indoors.

Last Frost Date

On average all chance of frost has passed is on April 15 in Denver. You can expect an average low temperature of -15°F in the coldest months of winter.

Since the USDA zone info for Denver is just an average the actual date of last frost can change quite a bit from year to year. Half of the time in Denver you get surprised by a frost after April 15 so be sure to be ready to cover your peonies in the event of a late frost.

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.