Cold Framing Greenhouse

By: Samantha Daggett

We are in Wisconsin and you know what that means…. cold weather. Unfortunately that means our gardens are covered in snow. What if I told you there was a way to keep growing yummy food year around. The answer is Cold Frame Greenhouses. So what is a cold frame? It is a structure that goes outside and is heated by the sun. Some of the cold will be let in so using plants that are very sensitive is not a good idea for most types of these greenhouses. These boxes are good to start seedlings as well. This creates a microclimate five to 10 degrees warmer than the weather outside. You might be thinking, we get into the negative numbers but using these cold framing greenhouses can extend your harvest.

Some of the plants that are able to go into cold frames are:

• Radish

• Lettuce

• Endive

• Scallion

• Chives

• Arugula

• Kale

• Mustard

• Spinach

What you are looking for when planting in these boxes will depend on the season but typically you will look for cold- hearty vegetables like beets, bulbs like tulips, and early season plants like sweet peas. 

For the best results this greenhouse needs to be in direct sunlight. Now because it is an enclosed space it doesn’t need to be watered frequently. Something else to remember is that the higher off the ground your greenhouse is the colder it will be. Once the top layer of soil is dry then you can add more water. On warmer days make sure there is some sort of ventilations so you don’t cook your plants. A lot of people like to use glass for their cold frames but in our Wisconsin weather it might be a good idea to use some sort of plastic or polycarbonate.

On the site Rural Sprouts they teach us how to make a cold frame that won’t cost a lot of money. The tools that they use is a large clear bin with a lid, potting soil, seeds and a power drill.

The first step is to drill holes into the bottom of the bin. This will create a way for the extra water to drain out. If this step is skipped there is risk for your plants roots to rot. To do this flip over the bin and slowly drill several holes into the bottom of the bin. 

The second step is to put the soil into the bin. Add 6 to 8 inches to the bin, and then flatten the soil with your hand or any other gardening tool to help.

The third step is to add your seeds. Here is where you can start your seeds to prepare them for being planted outside. You can put plants into a cold frame but in this case there is probably not enough room to keep plants alive.

Now you have your very own cold frame greenhouse.