One of the first steps you take when you are figuring out your gardening schedule is find your USDA Zone info. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

A common way of determining when to plant purple rock cress is to check out the USDA zone info for Longmont.

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 do well in cold which tells us that you can plant them much earlier than other plants that might not handle the cold.

The earliest that you can plant purple rock cress in Longmont 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. Starting your purple rock cress indoors is a great way to get them started a couple of weeks earlier.

Last Frost Date

In Longmont the average date of last frost happens on April 15. In the coldest months of winter you should expect an average low temperature of -15°F.

Remember that USDA zone info for Longmont may not be accurate from year to year and the actual date of last frost changes from year to year. Since half of the time in Longmont last frost occurs after April 15 be ready to cover your purple rock cress if you have a surprise late frost.

USDA Zone Info for Longmont

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 Longmont

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