How to Build a Manure Heated Hotbed For Early Seedlings

Manure heated hotbeds provide an effective method for cultivating early seedlings without requiring digging and are easier to manage than their counterparts.

Manure suitable for this use should be relatively fresh and not too heavy, and should be forked over after being piled to break up any lumps that form.

Build the Frame

Manure heated hotbed frames should be designed in such a way as to be protected from cold winds. A sloping roof with glass panes that only rise a few inches above soil level works well here; and surrounding it with board fencing or walls of hay bales provides additional insulation against windy conditions.

Manure for hotbeds should be prepared 10-14 days in advance and forked over regularly as it piles to break up lumps and evenly distribute the compost. Furthermore, dampening it can prevent it from decomposing prematurely.

Horse manure tends to heat more rapidly and hotter than other types of manure, making it the optimal choice. A combination of one part horse manure with two parts straw or other bedding material should usually suffice, though an electric heating cable could also be utilized in its place.

Build the Pit

Permanent manure hotbeds may be constructed out of concrete, while for less permanent purposes one may also be constructed from cheap ship lap lumber. When using this method, 2 by 4 cedar posts should be fastened at each corner and six-foot intervals along the sides with rot-resistant boards as forming frames to complete it.

Assuming it can be dug during winter months, ideally 18-24 inches deep pits for hotbeds should be dug. To provide bottom heat, cottonseed or other combustible material like chopped straw or fall leaves may be added as additional stable manure to add bottom heating properties.

As you pile, be sure to fork it well, adding about six inches of rich garden soil or compost as you go. When soil temperatures reach 60-70 degrees Fahrenheit, seeds may be planted and the sash attached*.

Build the Sash

Standard hotbed glass sashes measure 3×6 feet. A frame should be built around it to protect from rain or cold wind, and then filled with manure packed well into a pit by trampling. Once filled, an additional layer of soil or manure should be banked on its northern side to block out cold air. Ventilation plays an integral part in running hotbeds; on cooler days it should be propped up at either end or one side to allow in more warmth, while when temperatures climb too far the sash should be raised or removed altogether to prevent overcooling of an environment.

On cold nights, the sash should be covered with some form of insulation such as pieces of Styrofoam or rigid-board insulation set in place, old blankets or burlap bags, or bales of straw stacked against the sides of the frame for effective insulation.

Build the Insulation

Insulation may come in the form of straw bales, burlap sacks or old rugs; whatever works to keep manure warm during the day and kept warm as night falls is optimal.

Prep time for hotbed manure should begin 10 or 14 days in advance by piling the required amount in an open spot with plenty of drainage, and forking over it regularly to break up lumps and distribute litter evenly across its surface. Next, the pile must be dampened to promote rapid fermentation.

Preparing the soil correctly is vital for even heating and the elimination of weeds. Cottonseed makes an effective bottom heat source; however, for maximum effectiveness combine cottonseed with stable manure as bottom heat source for best results.