Before planting it is a good idea to find your USDA Zone info to estimate your garden schedule. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

The earliest that you can plant catharanthus in Oak Brook should be determined by looking at 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 do not do well in cold 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 Oak Brook 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 really do well. Starting your catharanthus indoors is a great way to get them started a couple of weeks earlier.

Last Frost Date

In Oak Brook the average date of last frost happens on April 15. In the coldest months of winter you can expect an average low temperature of -15°F.

Since the USDA zone info for Oak Brook is just an average the actual date of last frost will vary from year to year. Half of the time in Oak Brook it frosts late in the year after April 15 so always be ready to cover your catharanthus in the event of one of those late frosts.

USDA Zone Info for Oak Brook

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 Oak Brook

You may be interested in your other planting guides for Oak Brook.