Hot Box Gardening

For many gardeners, the dipping autumn temperatures come too soon, and the wait to return to gardening is much too long. However, gardeners living in cooler climates can extend their natural growing season by using a hot box or hot bed.

What Is a Hot Box?

A hot box is similar to a miniature heated greenhouse. The simplest form of a hot box is a bottomless frame that includes a heat source and is covered with a removable, transparent, sloping lid. By supplementing the heat of the sun with the additional heat source, gardeners can grow a wide range of vegetables and flowers - even during the coldest months.

How Can I Use a Hot Box?

Hot box gardening is useful for growing a variety of flowers and vegetables, but hot boxes are most commonly used to start seedlings before the ground thaws. It's also easy to turn a hot bed into a cold frame to grow hardy cold weather-tolerant crops, such as cabbage, throughout the winter by turning the supplementary heat off.

What's the Best Way to Build a Hot Box?

A hot box is a valuable addition to your garden, but it is critical to construct it correctly. When designing a hot box, consider your garden's soil and natural light along with the hot box's orientation. Ventilation is important to prevent overheating, and adding adequate insulation can help maintain higher temperatures while reducing heating costs.

There are many heating options you can select for hot boxes, but the most common tends to be electrical outdoor wiring buried under the box.

Hot boxes should be installed:

  • Over well-drained soil that is free from flooding
  • With a southern exposure to make the most of limited winter light
  • In a location that is sheltered from strong winds
  • Close to your home for easy accessibility to electricity, and for care in bad weather since plants in hot boxes typically require more watering.

Building a hot box garden is a common DIY project that can be completed over a weekend. However, if you are more of a green thumb than mechanically inclined, pre-made hot boxes are available at most garden supply centers and online.