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.

The USDA zone info for Aspen can be used to determine when it's the best time to plant doronicum.

Planting Calendar for Doronicum

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

Since doronicum do well in moderate cold you can plant them a little bit earlier in the year than more sensitive plants.

The earliest that you can plant doronicum 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 doronicum and expect a good harvest is probably September. Any later than that and your doronicum may not have a chance to grow to maturity. You can get started a couple of weeks earlier by starting your doronicum indoors.

Last Frost Date

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

Remember that the actual date of last frost may not be accurate from year to year because it is based on the USDA zone info for Aspen and it will vary from year to year. Since half of the time in Aspen there is a last frost after April 15 be ready to cover your doronicum if you have a late frost.

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.