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.

In Cynthiana you can figure out when it's the best time to plant catharanthus by using the USDA zone info.

Planting Calendar for Catharanthus

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

Since catharanthus are not cold tolerant it is important to wait until after the last frost before you can plant them.

The earliest that you can plant catharanthus in Cynthiana 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. Any later than that and your catharanthus may not have a chance to fully mature. If you are starting your catharanthus indoors then you might be able to get away with starting them a little bit earlier.

Last Frost Date

The average date of last frost is April 15 in Cynthiana. In the coldest months of winter you should expect an average low temperature of -5°F.

Since the USDA zone info for Cynthiana is just an average the actual date of last frost is different every year. Half of the time in Cynthiana you get surprised by a frost after April 15 so always be ready to protect your catharanthus in the event of one of those late frosts.

USDA Zone Info for Cynthiana

Here is the info for USDA Zone 6b.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-5°F
Highest Expected Low	0°F

This means that on a really cold year, the coldest it will get is -5°F. On most years you should be prepared to experience lows near 0°F.

Plants to Grow in Cynthiana

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