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

A common way of figuring out when you can plant anchusa is to consult the USDA zone info for Aspen.

Planting Calendar for Anchusa

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

Since anchusa do well in cold you can plant them much earlier in the year than plants that are more sensitive to the cold.

The earliest that you can plant anchusa 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 anchusa and expect a good harvest is probably September. Any later than that and your anchusa may not have a chance to grow to maturity. Starting your anchusa indoors is a great way to get them started a couple of weeks earlier.

Last Frost Date

On average the last frost is on April 15 in Aspen. You should expect an average low temperature of -15°F in the coldest months of winter.

Since the USDA zone info for Aspen may not be accurate from year to year the actual date of last frost will vary from year to year. Half of the time in Aspen you get surprised by a frost after April 15 so be sure to be ready to cover your anchusa 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.