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.

By looking at the USDA zone info for Billings it's possible to determine when you can plant aubrieta.

Planting Calendar for Aubrieta

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

Aubrieta are moderately cold tolerant which tells us that you can plant them earlier than more sensitive plants.

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

Last Frost Date

On average the last frost has passed is on May 15 in Billings. In the coldest months of winter you should expect an average low temperature of -25°F.

Always keep in mind that the actual date of last frost is an average because it is based on the USDA zone info for Billings and it can change quite a bit from year to year. Since half of the time in Billings last frost occurs after May 15 be ready to cover your aubrieta 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.