One of the best tools that you have as gardeners to help us estimate 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 way of estimating when it's a good idea to plant catharanthus is to consult the USDA zone info for Waterloo.

Planting Calendar for Catharanthus

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

You really shouldn't plant catharanthus until after all chance of frost has passed because they do not do well in cold weather.

The earliest that you can plant catharanthus in Waterloo 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 really do well. If you are starting your catharanthus indoors then you might be able to get away with starting them a couple of weeks earlier.

Last Frost Date

The average date of last frost is April 15 in Waterloo. In the coldest months of winter you can expect an average low temperature of -20°F.

Remember that the actual date of last frost may not be accurate from year to year because it is based on the USDA zone info for Waterloo and it can change quite a bit from year to year. Half of the time in Waterloo it frosts late in the year after April 15 so always be ready to cover your catharanthus if you have one of those late frosts.

USDA Zone Info for Waterloo

Here is the info for USDA Zone 5a.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-20°F
Highest Expected Low	-15°F

This means that on a really cold year, the coldest it will get is -20°F. On most years you should be prepared to experience lows near -15°F.

Plants to Grow in Waterloo

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