Before planting it is a good idea to find your USDA Zone info to determine your garden schedule. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

A way of figuring out when it's a good idea to plant purple rock cress is to examine the USDA zone info for Altoona.

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.

Purple Rock Cress are one of those plants that can tolerate quite a bit of cold weather which means that you can plant them a quite a bit earlier than other frost tender plants.

The earliest that you can plant purple rock cress in Altoona 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 purple rock cress and expect a good harvest is probably August. Any later than that and your purple rock cress may not have a chance to grow to maturity. If you are starting your purple rock cress indoors then you might be able to get away with starting them a few weeks earlier.

Last Frost Date

The average date of last frost is May 15 in Altoona. You can expect an average low temperature of -25°F in the coldest months of winter.

It's important to remember that the actual date of last frost is an average because it is based on the USDA zone info for Altoona and it is different every year. Since half of the time in Altoona last frost occurs after May 15 be ready to protect your purple rock cress if you have a surprise late frost.

USDA Zone Info for Altoona

Here is the info for USDA Zone 4b.

Average Date of Last Frost (spring)	May 15
Average Date of First Frost (fall)	September 15
Lowest Expected Low	-25°F
Highest Expected Low	-20°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 -20°F.

Plants to Grow in Altoona

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