One of the best tools that you have as gardeners to help us figure out 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.

A common way of making a decision about when it's the best time to plant achimenes is to refer to the USDA zone info for Spearfish.

Planting Calendar for Achimenes

Frost tolerance for achimenes:	Not tolerant of frost.
When to plant:	After the last frost when the weather gets warmer.

It's a bad idea to plant achimenes until after the last frost when the weather gets warmer because they do not do well in cold weather.

The earliest that you can plant achimenes in Spearfish is April. However, you really should wait until May if you don't want to take any chances.

The last month that you can plant achimenes and expect a good harvest is probably August. Any later than that and your achimenes may not have a chance to grow to maturity. You can get started a little bit earlier by starting your achimenes indoors.

Last Frost Date

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

Just be sure to remember that the actual date of last frost may not be accurate from year to year because it is based on the USDA zone info for Spearfish and it changes from year to year. Since half of the time in Spearfish you get a frost after April 15 be ready to protect your achimenes in the event of 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.