Before planting it is a good idea to find your USDA Zone info to determine your garden schedule. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

A way of estimating when it's the best time to plant angel's trumpets is to use the USDA zone info for Helena.

Planting Calendar for Angel's Trumpets

Frost tolerance for angel's trumpets:	Tolerant of a very small amount of frost.
When to plant:	Up to 3 weeks before last frost.

Angel's Trumpets tend to make it in some cold which tells us that you can plant them slightly earlier in the year than plants that are more sensitive to the cold.

The earliest that you can plant angel's trumpets in Helena 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 angel's trumpets and expect a good harvest is probably August. Any later than that and your angel's trumpets may not have a chance to grow to maturity. Starting your angel's trumpets indoors is a great way to get them started a little bit earlier.

Last Frost Date

The average date of last frost is March 15 in Helena. In the coldest months of winter you should expect an average low temperature of 10°F.

Since the USDA zone info for Helena may not be accurate from year to year the actual date of last frost changes from year to year. Since half of the time in Helena you get surprised by a frost after March 15 be ready to cover your angel's trumpets if you have 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.