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

It's possible to figure out when you can plant angel's trumpets by looking at the USDA zone info for Spearfish.

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 are one of those plants that can tolerate a tiny bit of cold weather which tells us that you can get them planted just a bit earlier than plants that are more sensitive to the cold.

The earliest that you can plant angel's trumpets in Spearfish 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. You probably don't want to wait any later than that or else your angel's trumpets may not have a chance to fully mature. You can get started a couple of weeks earlier by starting your angel's trumpets indoors.

Last Frost Date

The average date of last frost is April 15 in Spearfish. You should expect an average low temperature of -20°F in the coldest months of winter.

Since the USDA zone info for Spearfish is an average the actual date of last frost can change quite a bit from year to year. Since half of the time in Spearfish you get a frost after April 15 be ready to protect your angel's trumpets if you have one of those late frosts.

USDA Zone Info for Spearfish

Here is the info for USDA Zone 5a.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-20°F
Highest Expected Low	-15°F

This means that on a really cold year, the coldest it will get is -20°F. On most years you should be prepared to experience lows near -15°F.

Plants to Grow in Spearfish

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