Before planting it is a good idea to find your USDA Zone info to figure out 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.

In Aspen you can determine when it's the best time to plant catharanthus by checking out 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 require warm weather it's necessary to wait until after the last frost when the weather gets warmer before you can plant them.

The earliest that you can plant catharanthus in Aspen 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 fully mature. Starting your catharanthus indoors is a great way to get them started a few weeks earlier.

Last Frost Date

In Aspen the average date of last frost happens on April 15. You can expect an average low temperature of -15°F in the coldest months of winter.

Since the USDA zone info for Aspen may not be accurate from year to year the actual date of last frost is different every year. Half of the time in Aspen there is a last frost after April 15 so make sure that you are prepared to protect your catharanthus in the event of one of those late frosts.

USDA Zone Info for Aspen

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 Aspen

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