Using cold frames to start early in the spring

Producing fresh vegetables early in spring is possible and it does not take a lot of work or expense. Some garden vegetables that can be grown in a cold frame include lettuce, radish, spinach, onions, greens, and others. Oh yes, and lamb’s quarters also grow well if those appeal to you as a green. So if you want to get your hands into the warm spring soil sooner, and taste the sweet tender goodies earlier than your neighbors, please read on.

What is a cold frame you may ask? Well, it is like a very small greenhouse that is low to the ground which allows cold-tolerant vegetables to grow when it is otherwise much too cold outside. The typical design is a very simple one-foot high wooden box with no bottom and clear glass covering on top. It’s really simple to make—you can do it!

First you need to find a location where you will put your cold frame. It should be sheltered from winds while having good exposure to direct sunlight, usually the south side of your house works best. I would also pick a spot close to the home’s foundation where the soil is little warmer. You will have to check the cold frame often during certain weather conditions, so it also needs to be located in a place that is easily accessible.

For materials, I suggest starting with an old window. A neighbor that is doing a house renovation or local contractors could likely point you in the direction of where you could find one. The next step is to use some boards to make a box slightly smaller than the window. The box is placed on the ground and the window is placed on top, and is usually secured with hinges. Adding an incandescent light bulb (a simple trouble-light is ideal) can provide heat on very cloudy or windy days or nights, and voila, you’re done! If you feel really ambitious, you could also place a heating coil about 1 inch deep which will warm the soil all spring. You will have to be careful not to use garden tools in the soil in the cold frame or you will damage the coil. A thermometer can be handy, allowing you to ensure soil and air temperatures are correct before you put plants inside it.

You can set up the cold frame in early April and allow the soil to warm up for a couple of weeks. When the soil has warmed up, you should start to work in some compost and lime. If you are close to a foundation it is especially important to add nutrients as there is often subsoil in that area. Once you see a few weeds starting to germinate it should be ok to plant your veggies.

The seeds (or seedlings) are placed in the ground in rows similar to how you would in your garden. Since the cold frame is small, the rows are close together, but far enough apart to allow the plants space to mature. If you have transplants that you had growing indoors, you should put them in the cold-frame still in their pots for a few days to get accustomed to the growing conditions before transplanting them in the soil.

Once the plants are growing, one of the key factors for success in using a cold frame is to be aware of the sun. On a bright, sunny day, even if it’s cold outside, it can become hot in the cold frame quickly, so you will need to monitor the temperature. As necessary, you can prop the glass open with a wooden stake, which allows the excess heat to escape. If it is cold out, and/or the sun goes behind a cloud, then your cold-frame can cool quickly so you need to develop the knack of being mindful of the sun. On cold nights you can throw an old blanket over the top to keep the heat in.

If you have room in your cold frame, you can also move your seedling transplants that you started for the garden into it during the daytime, so they are exposed to the strong sunlight. Do not forget to move them back indoors at night though. Depending on what veggies you pick, if you plant in April, you can harvest in May. Happy gardening!

About Christopher Dunbar

Christopher lives in western PEI along with his spouse and 4 kids, on a property that was once owned by his great grandparents. He grew up in a large farming family and has deep island roots. This rural background and exposure to outdoor living has given him a keen interest in our maritime culture and the many plant types that grow here. He furthered his interest in growing things by obtaining a master’s degree in in plant biology. Not surprisingly, all of his 25-year career has been involved in agriculture and food. He spends some of his spare time growing berries, flowers, vegetables and tree fruits of all kinds in his gardens. He and his family really enjoy the unique lifestyle that PEI has to offer.
Writing creatively about adventures in rural living is also one of his passions. Feel free to contact him if you want to share any of your interests.

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