Planning the Perfect Hotbed Location For Early Spring Starts

Hotbeds (or upgraded cold frames) allow you to start seeds and seedlings two to three months earlier than without polytunnels, and selecting an ideal location is key to its success.

An effective and easy way to create a hotbed is by mixing fresh horse manure with chopped fallen leaves, then covering it with a frame.

Location

Although backyard greenhouses have made hot beds less prevalent, their versatility still outshines cold frames when it comes to starting tender seeds and developing plants early. Hotbeds can be constructed as low boxes or frames buried into the soil or placed atop existing garden beds and covered with glass, polycarbonate or plastic sheets; their contents typically consist of sand, wood shavings or compost (preferably horse manure for its organic matter content), six inches of rich garden soil mix that won’t puddle when water is applied and some kind of cover material such as glass, polycarbonate or plastic sheets for covering.

Temperature

A hotbed is similar to a cold frame but provides additional heat energy through electric heating cables. As with cold frames, hotbeds can help protect tender plants during the winter season while hardening started vegetable seedlings for outdoor transplanting or initiating cool season crops early on in their growth cycles.

To build an electrically heated hotbed, dig a pit in early winter months and fill it with manure, covering it with one inch of sand and hardware cloth as support structure. Ideally, this pit should be 18-24 inches deep with level bottom surface.

Add coarse charcoal to the sand before covering it with topsoil or compost to complete your pit. Install heating cable at its base, as well as main thermostat switch and individual unit switches (see diagram) for controlling multiple units of your hotbed.