The USDA Zone info is a great tool for gardeners to help us figure out 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 earliest that you can plant catharanthus in Tucson should be determined by referring to 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.

Catharanthus do not do well in cold weather which means that it's important to wait until it warms up after all chance of frost has passed before you can plant them.

The earliest that you can plant catharanthus in Tucson is March. However, you really should wait until April if you don't want to take any chances.

The last month that you can plant catharanthus and expect a good harvest is probably September. 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 few weeks earlier.

Last Frost Date

In Tucson the average date of last frost happens on February 15. In the coldest months of winter you can expect an average low temperature of 25°F.

Since the USDA zone info for Tucson is just an average the actual date of last frost is different every year. Since half of the time in Tucson it frosts late in the year after February 15 be ready to cover your catharanthus if you have one of those late frosts.

USDA Zone Info for Tucson

Here is the info for USDA Zone 9b.

Average Date of Last Frost (spring)	February 15
Average Date of First Frost (fall)	December 15
Lowest Expected Low	25°F
Highest Expected Low	30°F

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

Plants to Grow in Tucson

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