What is a Cold Frame?

A cold frame is a handy structure to have in a garden as it allows you to extend the harvest of cool and cold season crops in the late autumn and even winter.

Cold Frame Crops

I harvest many types of vegetables during the cold season, including scallions, salad greens and root vegetables. And while we eat these crops beyond the traditional growing season, the seeds or seedlings are planted from mid-summer to early autumn, depending on the vegetable.

Here I've got Salanova® lettuces, which form dense heads of tender leaves, and Kalebration Kale Mix, a blend of eye catching green and red varieties, perfect for baby greens. Greens like these are very quick to grow. Check your seed packets for specific days to maturity information. You can direct sow seeds or give them a head start indoors under grow lights.

Once the seedlings are 3 to 4 weeks old, they're hardened off and transplanted into the cold frame. Other great options for an autumn or winter cold frame include arugula, mâche and Asian greens like Amara Mustard and Red Kingdom Mizuna.

Growing Tips for the Cold Frame

• Watering

  Once the seeds are planted, it's important to pay attention to soil moisture — aim to keep the soil lightly moist to promote healthy plant growth.

• Ventilation

  You'll also need to ventilate the cold frame on mild days by opening up the top to release any buildup of warm air. I prop open the tops of my cold frames any time the daytime temperature is above 40 degrees Fahrenheit or 4 degrees Celsius. If it's going to be a very warm day, I'll completely open the frame, closing it up again later in the afternoon or early evening.

• Harvest

  Once the plants have reached the right size, you can harvest by picking individual leaves and allowing the plant to continue growing for future harvests or you can cut the entire head.

Happy growing!

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