Tuesday, August 29, 2023

Cold Frames - Making the Best Choice by Gregory Engel


Photo credit:  Extension, University of Maine 
https://extension.umaine.edu/publications/2752e/

If you've gardened in Colorado for more than a few years, you know it's a challenging climate. Conditions vary from the drought days of the early 2000's to the unusually wet and cool spring and summer we've had here in 2023. Add to this a wide variation in elevation zones. More often than not, we wish for an extended growing season. A popular approach to achieving this goal is to set up cold frames structures that extend the growing season by creating a micro-climate favorable to either starting plants earlier in the spring or continue growing them late into fall, perhaps even throughout the winter.

Photo credit: WallpaperFlare.com

This article is meant to compliment the excellent series of cold frame articles by Susan Perry from 2014 (see links below.) I really can't improve on what Susan has written. When you've made the decision to give cold frame gardening a go, she has all the details and troubleshooting laid out for success. This article will focus more on the up front decision part of cold frame gardening. I'll explore several aspects of things to consider when making the determination of whether to venture into this specialized approach to gardening.

Photo credit: CSU Extension - G&G Blog, September 2022

As Susan's series of articles illustrate, cold frame gardening has a unique set of challenges to overcome in order to be successful. Here are a few things to consider when considering cold frame gardening.

Temperature - As the saying goes, if you don't like the weather in Colorado, wait 15 minutes. It'll change. We can experience temperature changes that are both rapid and wide. The design of a cold frame is such that it will trap heat, but under the right conditions they can trap too much heat. It's important to have adequate ventilation. Until experience is gained, it's import to regularly monitor the internal temperature of your cold frame to prevent overheating or excessive cooling. Have a plan in place for extra protection to accommodate late spring and early fall frosts.

Sunlight - Know where you can place your cold frame to maximize the fall and winter sunlight. Do you live in the shadow of a mountain or in a micro-climate that has a higher frequency of cloudy days? The larger context of geography will influence how much control you have over extending your garden's growing season.

Wind - The front range can experience sudden and strong winds as cold air from the mountains drops to the plains, warming as it goes. I've lived in Colorado all my life and I occasionally need a reminder of this fact. After setting up my first cold frame with a nice fitting top, I left attaching the hinges for the next day, thinking the lid was heavy enough to stay in place. Sure enough, a strong wind storm over night picked up the lid and blew it onto a fence post. Lucky, I'd used Plexiglas rather then my original plan to use actual glass.

Elevation - The elevation at which you build out your cold frames can significantly influence the viability of the cold frame micro-climate. What works for me in Golden (6,000 feet) probably won't work as well in Evergreen (7,000+ feet). It will be important to experiment and keep careful notes for what works for you.

Water and Soil - Spring/summer 2023 notwithstanding, Colorado is best characterized as an arid climate. As with temperature, frequent monitoring of your cold frame to be sure it isn't drying out is important.

Pests - The micro-climate you hope to set up for your plants will also be desirable to a variety of pests. Include with your temperature and humidity monitoring regimen frequent checks for insects, rodents, and fungal issues.• Pests - The micro-climate you hope to set up for your plants will also be desirable to a variety of pests. Include with your temperature and humidity monitoring regimen frequent checks for insects, rodents, and fungal issues.

References