One of the best tools that you have as gardeners to help us figure out your gardening schedule is the USDA zone info. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

A common way of determining when it's possible to plant catharanthus is to check out the USDA zone info for Exeter.

Planting Calendar for Catharanthus

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

Since catharanthus do not do well in cold weather you have to wait until after all chance of frost has passed before you can plant them.

The earliest that you can plant catharanthus in Exeter 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 catharanthus and expect a good harvest is probably September. If you wait any later than that and 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 February 15 in Exeter. It might get as low as 25°F during the coldest months of winter.

Since the USDA zone info for Exeter is just an average the actual date of last frost can change quite a bit from year to year. Since half of the time in Exeter you get surprised by a frost after February 15 be ready to cover your catharanthus if you have a surprise late frost.

USDA Zone Info for Exeter

Here is the info for USDA Zone 9b.

Average Date of Last Frost (spring)	February 15
Average Date of First Frost (fall)	December 15
Lowest Expected Low	25°F
Highest Expected Low	30°F

This means that on a really cold year, the coldest it will get is 25°F. On most years you should be prepared to experience lows near 30°F.

Plants to Grow in Exeter

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