One of the first steps you take when you are figuring out your gardening schedule is find your USDA Zone info. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

A common way of determining when to plant catharanthus is to consult the USDA zone info for Winthrop Harbor.

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's necessary to wait until after the last frost has passed before you can plant them.

The earliest that you can plant catharanthus in Winthrop Harbor 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. 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

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

It's important to remember that USDA zone info for Winthrop Harbor may not be accurate from year to year and the actual date of last frost changes from year to year. Since half of the time in Winthrop Harbor there is a last frost after April 15 be ready to cover your catharanthus if you have one of those late frosts.

USDA Zone Info for Winthrop Harbor

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 Winthrop Harbor

You may be interested in your other planting guides for Winthrop Harbor.