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

A way of estimating when to plant anchusa is to check out the USDA zone info for Billings.

Planting Calendar for Anchusa

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

You can plant anchusa much earlier in the year because they do well in cold.

The earliest that you can plant anchusa in Billings 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 anchusa and expect a good harvest is probably August. If you wait any later than that and your anchusa may not have a chance to grow to maturity. If you are starting your anchusa indoors then you might be able to get away with starting them a little bit earlier.

Last Frost Date

In Billings the average date of last frost happens on May 15. You can expect an average low temperature of -25°F in the coldest months of winter.

Keep in mind that USDA zone info for Billings may not be accurate from year to year and the actual date of last frost changes from year to year. Half of the time in Billings you get surprised by a frost after May 15 so be sure to be ready to protect your anchusa in the event of a late frost.

USDA Zone Info for Billings

Here is the info for USDA Zone 4b.

Average Date of Last Frost (spring)	May 15
Average Date of First Frost (fall)	September 15
Lowest Expected Low	-25°F
Highest Expected Low	-20°F

This means that on a really cold year, the coldest it will get is -25°F. On most years you should be prepared to experience lows near -20°F.

Plants to Grow in Billings

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