One of the best tools that you have as gardeners to help us figure out your gardening schedule is the USDA zone info. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

You can figure out when it's a good idea to plant purple rock cress in Irmo by using the USDA zone info.

Planting Calendar for Purple Rock Cress

Frost tolerance for purple rock cress:	Very tolerant of frost.
When to plant:	Up to 7 weeks before last frost.

Since purple rock cress are one of those plants that can tolerate quite a bit of cold weather you can plant them earlier in the year than plants that are more sensitive to the cold.

The earliest that you can plant purple rock cress in Irmo is February. However, you really should wait until March if you don't want to take any chances.

The last month that you can plant purple rock cress and expect a good harvest is probably September. You probably don't want to wait any later than that or else your purple rock cress may not have a chance to really do well. If you are starting your purple rock cress indoors then you might be able to get away with starting them a little bit earlier.

Last Frost Date

On average the last frost when the weather gets warmer is on March 15 in Irmo. You should expect an average low temperature of 10°F in the coldest months of winter.

Since the USDA zone info for Irmo may not be accurate from year to year the actual date of last frost changes from year to year. Half of the time in Irmo you get surprised by a frost after March 15 so be sure to be ready to protect your purple rock cress if you have a surprise late frost.

USDA Zone Info for Irmo

Here is the info for USDA Zone 8a.

Average Date of Last Frost (spring)	March 15
Average Date of First Frost (fall)	November 15
Lowest Expected Low	10°F
Highest Expected Low	15°F

This means that on a really cold year, the coldest it will get is 10°F. On most years you should be prepared to experience lows near 15°F.

Plants to Grow in Irmo

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