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When to Plant Purple Rock Cress in Columbia Falls, MT

The USDA Zone info is a great tool for gardeners to help us figure out your gardening schedule. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

The first chance to plant purple rock cress in Columbia Falls can be figured out by referring to 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.

Purple Rock Cress do well in quite a bit of cold which means that you can plant them a lot earlier in the year than plants that are more sensitive to the cold.

JanFebMarAprMayJunJulAugSepOctNovDec
Legend 
A good time to plant purple rock cress
Possibly ok, but a risky time to plant purple rock cress
Probably not a good time to plant purple rock cress

The earliest that you can plant purple rock cress in Columbia Falls 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. If you wait any later than that and your purple rock cress may not have a chance to fully mature. 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

On average the last frost when the weather gets warmer is on April 15 in Columbia Falls. In the coldest months of winter you should expect an average low temperature of -20°F.

Since the USDA zone info for Columbia Falls is not always accurate the actual date of last frost is different every year. Since half of the time in Columbia Falls you get surprised by a frost after April 15 be ready to cover your purple rock cress if you have a late frost.

USDA Zone Info for Columbia Falls

Here is the info for USDA Zone 5a.

Average Date of Last Frost (spring)April 15
Average Date of First Frost (fall)October 15
Lowest Expected Low-20°F
Highest Expected Low-15°F

This means that on a really cold year, the coldest it will get is -20°F. On most years you should be prepared to experience lows near -15°F.

Plants to Grow in Columbia Falls

You may be interested in your other planting guides for Columbia Falls.