Extend Your Season With A Cold Frame or Greenhouse

Is it possible to grow your heirloom seeds in the summer and extend it until fall and winter -- or start your seedlings and tender transplants early in the spring? Then you should think about buying a greenhouse or cold frame you can use all year round!

If you are new to this, let’s start by understanding what a cold frame is. The cold frame is a hollow box or structure with a transparent plastic or glass top that is placed on the ground or over a sunken bed. This structure provides solar heating and wind protection for your seedlings and tender starts. Sunlight enters the cold frame through the transparent cover, which creates a greenhouse effect that heats the inside.

The designs of cold frames vary widely. A popular one is a wooden box with an easily opened, clear cover that is adjustable. You can build a cold frame using old windows or purchase greenhouses or cold frames online.

Cold Frames: How To Use Them

As long as you know how to properly use a cold frame, it is possible to extend the growing season from one month to three months. In addition, cold frames are used to start seedlings earlier, harden off seedlings, and overwinter delicate, dormant plants.

A cold frame needs care, just like a conventional garden bed. You need to ensure soil replenishment, uniform hydration, suitable ventilation, labeling plants, and re-seeding. Make sure to close manual frames at the end of the day because young plants left in closed cold frames on warm days can die from overheating.

Here are some helpful tips to get you started on using your cold frames.

  • Ventilate the frame if it gets too warm. Cover the glass with hay or another type of cushioning if the cold frame is too chilly to prevent heat loss.
  • A 70 degrees temperature is a decent compromise for most crops.
  • Water in the morning, so there is enough time for the soil to dry before you close the frame.
  • Direct-sown and transplanted plants will require only a bit of water since the cold frame can keep moisture and retain the cool temperature.
  • Position the cold frame slanted so the plants get maximum exposure to sunlight. A few inches should separate the back wall and the front wall. A general rule of thumb is to add 20 degrees to your latitude to get the best angle from the horizon.
  • Don’t let water sit in your cold frame. Set up a good drainage system to prevent the roots from drowning.

Would you like to harvest abundant crops throughout the year? Keeping a cold frame will help you harvest a bountiful crop! 

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