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.

One way of getting a good idea when to plant catharanthus is to consult the USDA zone info for Rapid City.

Planting Calendar for Catharanthus

Frost tolerance for catharanthus:	Not tolerant of frost.
When to plant:	After all chance of frost has passed.

You really shouldn't plant catharanthus until after the last frost has passed because they do not do well in cold weather.

The earliest that you can plant catharanthus in Rapid City 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 catharanthus and expect a good harvest is probably August. You probably don't want to wait any later than that or else your catharanthus may not have a chance to grow to maturity. If you are starting your catharanthus indoors then you might be able to get away with starting them a few weeks earlier.

Last Frost Date

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

Always keep in mind that the actual date of last frost is not always accurate because it is based on the USDA zone info for Rapid City and it will vary from year to year. Since half of the time in Rapid City it frosts late in the year after April 15 be ready to cover your catharanthus in the event of a late frost.

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.