If you ignore Grand Junction and La Junta, most of Colorado normally experiences the first frost of fall sometime in late September or October. And yet, it’s October 27 and there hasn’t been a fall frost. Weird. Colorado is definitely unpredictable.
So what does this extended fall mean to our landscape plants? Here’s a short video where I address that very question.
The golden nuggets from the video are the following:
- The extended fall has allowed plants to go into dormancy gradually. This is pretty unusual, but a good thing for most of our landscape plants. Most of the time their dormancy process gets rudely interrupted by dramatic temperature changes in fall.
- Those plants that haven’t yet gone into dormancy are still using water. It’s important to make sure your soil is sufficiently moist so your plants don’t dehydrate and possibly die. Our plants are using more water than they normally do in fall because they’ve retained more leaves than usual.
- The last week of October is a great time to fertilize your lawn one last time. Go here to learn more.
Here’s a nifty interactive map of Colorado that shows the average first fall frost. You can zoom in on your location and see what the average is. But remember, nothing in Colorado happens on the “average” date!
Hi Catherine, looks I did get some frost last night. Even if some of my native perennials are still green, can I hold off on watering them at this point, until the spring? Just wasn’t sure if first frost = immediate dormancy! Thanks.
Hi Luke, yes, isn’t that funny timing? It dropped to 29 degrees in Colorado Springs last night. My understanding is that you can tell when plants have gone dormant because they lose their leaves (if they’re not evergreen plants). For many landscape plants, the first frost is what triggers the leaves to drop– even though it may take a week or more for them to actually fall off. With native perennials, I’m not too worried about watering them in fall since they’re usually well adapted to drier winter conditions. It’s probably fine to hold off watering unless we get an extended dry spell. But introduced landscape plants usually don’t fare so well with warm fall weather, dry soil, and dry winter conditions. You’re smart to use natives; less work and more resilient beauty.
Thanks Catherine!
Is now an okay time to shape (trim) blue spruce? What about trimming other decidious trees?
Hi Don, In Colorado it’s better to prune in late winter/early spring, like in February to March. The reason is that deciduous trees are going dormant right now and pruning sometimes stimulates new growth, which interrupts the dormancy mechanisms in trees. Spruces don’t go fully dormant since they are evergreen, but they’re growth and metabolism slows down in winter months. February and March is a much better time to prune since the trees are fully dormant (or semi-dormant for evergreens). Also, the danger of sub-zero temperatures, which can damage the bark around new pruning cuts, is usually passed. However, if you have a few problematic branches that need to be removed now, a little pruning is usually okay.