Hot Frames

By: Gwen Miner, Supervisor of Domestic Arts

Do you have access to fresh horse manure? Do you have some lumber and a window sash? If you do, you can build yourself a hot frame to start your garden plants or extend your growing season. Hot frames have been used for a couple of centuries at least by gardeners to start plants for their gardens. The advantage of these frames is that they give you an additional 4-6 weeks growing time. All you need is a nice steaming pile—several wheelbarrow loads—of horse manure with bedding material mixed in (not sawdust, it makes the soil too harsh), some lumber to make a frame and a window sash to cover the frame with. The rule of thumb in building the frame is to make the back 2 times higher than the front and large enough to fit your window sash. The front of the frame is slanted to admit more light and to shed rain. Patrick MacGregor, Supervisor of Pharmacy and Historic Gardens and I set up one of the two hot frames at the Lippitt Farmstead the first week in April. Here is a step by step in pictures to help you set up your own hot frame. First, we selected the site and piled the horse manure to make a base for the hot frame. Second, we put the frame together on top of the horse manure facing southeast. Third, we began to fill the frame with manure, firmly stomping the manure every 6” until it was about 8” from the top of the frame. Fourth, we covered with 6” of soil composted from last years’ frames, and then put the window sash on. Finally, we let the frame set for several days as the manure heated up to 125 degrees. If you plant your seeds right after creating your frame, the temperature will be too hot and you will scald your plants. When the temperature dropped to 85 degrees, I planted the frame and watered it. Sprouts began to appear before the first week was up, and after a few weeks, our hot frame is full of healthy plants on their way to maturity.