One of the first steps you take when you are getting a good idea your gardening schedule is find your USDA Zone info. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

The earliest that you can plant catharanthus in Somersworth can be estimated by looking at the USDA zone info.

Planting Calendar for Catharanthus

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

Since catharanthus require warm weather you need to wait until after all chance of frost has passed before you can plant them.

The earliest that you can plant catharanthus in Somersworth 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 fully mature. You can get started a few weeks earlier by starting your catharanthus indoors.

Last Frost Date

On average the last frost when the weather gets warmer is on April 15 in Somersworth. It might get as low as -15°F during the coldest months of winter.

Keep in mind that the actual date of last frost is just an average because it is based on the USDA zone info for Somersworth and it can change quite a bit from year to year. Half of the time in Somersworth you get surprised by a frost after April 15 so make sure that you are prepared to cover your catharanthus if you have a surprise late frost.

USDA Zone Info for Somersworth

Here is the info for USDA Zone 5b.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-15°F
Highest Expected Low	-10°F

This means that on a really cold year, the coldest it will get is -15°F. On most years you should be prepared to experience lows near -10°F.

Plants to Grow in Somersworth

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