After moving to Colorado from St. Louis 23 years ago, I popped over to a local nursery in late March, all eager to buy plants for my new garden. Surprisingly, there were almost no outdoor plants on display.
When I asked why, the nursery employee patiently explained that the growing season starts later in Colorado than it does in Missouri, because Colorado can still get frosts well into May.
This year is living proof of a late-season frost. Today is April 29. Last night, the temperature dropped to 31 degrees Fahrenheit in Fort Collins, and tonight it’s supposed to drop to 29. And there’s snow on the ground That’s why it’s advisable to wait until after mid-May to plant annuals along Colorado’s Front Range. Hardy perennials, trees and shrubs–fine. But wait on the annuals, unless you want to plant cold-season vegetables, such as lettuce. You can plant those in March or April.
So if you’re new to Colorado and are eager to start growing annuals and other tender plants, hold off a little. If you’ve already planted tender plants, they may be goners this year unless you covered them with a bucket or some such last night. Then again, the snow may have insulated them sufficiently to keep them alive. At any rate, cover them tonight.
May 19, 2017 update: Yesterday Fort Collins received eight, count ’em, eight inches of snow. Today, we may get a smattering before temperatures rise into the 50’s tomorrow.