The USDA Zone info is a great tool for gardeners to help us estimate 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.

The USDA zone info for Duluth should be reviewed to figure out when it's possible to plant catharanthus.

Planting Calendar for Catharanthus

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

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

The earliest that you can plant catharanthus in Duluth is May. However, you really should wait until June 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. If you wait any later than that and your catharanthus may not have a chance to really do well. Starting your catharanthus indoors is a great way to get them started a few weeks earlier.

Last Frost Date

In Duluth the average date of last frost happens on May 15. You should expect an average low temperature of -30°F in the coldest months of winter.

Remember that USDA zone info for Duluth is not always accurate and the actual date of last frost will vary from year to year. Since half of the time in Duluth last frost occurs after May 15 be ready to protect your catharanthus if you have a late frost.

USDA Zone Info for Duluth

Here is the info for USDA Zone 4a.

Average Date of Last Frost (spring)	May 15
Average Date of First Frost (fall)	September 15
Lowest Expected Low	-30°F
Highest Expected Low	-25°F

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

Plants to Grow in Duluth

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