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

The USDA zone info for Rapid City can be looked at to estimate when it's the best time to plant gomphrena.

Planting Calendar for Gomphrena

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

You can plant gomphrena just a tiny bit earlier in the year because they are barely cold tolerant.

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

Last Frost Date

On average all chance of frost has passed is on April 15 in Rapid City. It might get as low as -20°F during the coldest months of winter.

Since the USDA zone info for Rapid City is an average the actual date of last frost changes from year to year. Since half of the time in Rapid City last frost occurs after April 15 be ready to cover your gomphrena if you have one of those late frosts.

USDA Zone Info for Rapid City

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 Rapid City

You may be interested in your other planting guides for Rapid City.