The USDA Zone info is a great tool for gardeners to help us determine 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.

By looking at the USDA zone info for Aspen it's a good idea to determine when it's possible to plant larkspur.

Planting Calendar for Larkspur

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

Larkspur are one of those plants that can tolerate quite a bit of cold weather which tells us that you can plant them a quite a bit earlier than other plants that might not handle the cold.

The earliest that you can plant larkspur 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 larkspur and expect a good harvest is probably September. If you wait any later than that and your larkspur may not have a chance to fully mature. You can get started a few weeks earlier by starting your larkspur indoors.

Last Frost Date

On average the last frost when the weather gets warmer is on April 15 in Aspen. It might get as low as -15°F during 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 can change quite a bit from year to year. Half of the time in Aspen last frost occurs after April 15 so always be ready to protect your larkspur if you have one of those late frosts.

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.