Before planting it is a good idea to find your USDA Zone info to determine 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 USDA zone info for Siloam Springs should be reviewed to figure out when it's a good idea to plant catharanthus.

Planting Calendar for Catharanthus

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

It's not a good idea to plant catharanthus until after the last frost because they are not cold tolerant.

The earliest that you can plant catharanthus in Siloam Springs 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 fully mature. Starting your catharanthus indoors is a great way to get them started a little bit earlier.

Last Frost Date

The average date of last frost is April 15 in Siloam Springs. In the coldest months of winter you can expect an average low temperature of 0°F.

Since the USDA zone info for Siloam Springs is just an average the actual date of last frost can change quite a bit from year to year. Half of the time in Siloam Springs you get surprised by a frost after April 15 so make sure that you are ready to cover your catharanthus in the event of a surprise late frost.

USDA Zone Info for Siloam Springs

Here is the info for USDA Zone 7a.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	0°F
Highest Expected Low	5°F

This means that on a really cold year, the coldest it will get is 0°F. On most years you should be prepared to experience lows near 5°F.

Plants to Grow in Siloam Springs

You may be interested in your other planting guides for Siloam Springs.