One of the best tools that you have as gardeners to help us estimate your gardening schedule is the USDA zone info. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

It's a good idea to figure out when it's the best time to plant aubretia by reviewing the USDA zone info for Helena.

Planting Calendar for Aubretia

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

Aubretia are very cold tolerant which tells us that you can plant them much earlier than other frost tender plants.

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

Last Frost Date

In Helena the average date of last frost happens on March 15. You can expect an average low temperature of 10°F in the coldest months of winter.

Keep in mind that USDA zone info for Helena is just an average and the actual date of last frost is different every year. Half of the time in Helena last frost occurs after March 15 so always be ready to cover your aubretia in the event of a late frost.

USDA Zone Info for Helena

Here is the info for USDA Zone 8a.

Average Date of Last Frost (spring)	March 15
Average Date of First Frost (fall)	November 15
Lowest Expected Low	10°F
Highest Expected Low	15°F

This means that on a really cold year, the coldest it will get is 10°F. On most years you should be prepared to experience lows near 15°F.

Plants to Grow in Helena

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