Is Heating Necessary For A Greenhouse In North Alabama?

Photosynthesis requires sunlight and heat for plants to function properly. In the southeastern United States, greenhouses require year-round ventilation and can reach temperatures as high as 78 degrees in winter and 68 degrees in summer. Controlling the greenhouse environment can be challenging due to their ability to gain and lose heat. In zone 7b (Northern AL), a partially underground greenhouse (walipini) or installing a climate battery may be necessary. Greenhouses do not maintain their own heat, and need a heat source such as the sun, electric, or gas heaters. Supplemental heating is not necessary to extend the growing season, as the air is sufficient. In some cases, greenhouses may be considered an “accessory dwelling” and require a permit. The warm, humid climate of the state is ideal for many garden pests, and greenhouses can act as a barrier, reducing pest damage and the need for chemical controls.

Do greenhouses need to be heated?

Greenhouse hobbyists often need to add a heating system to keep their greenhouse operational year-round. The three most common ways to heat a greenhouse are gas, electric, and passive solar heat. Gas heating is the least expensive option, but open flame heaters can cause issues for budding plants and have safety oxygen sensors that automatically turn off when depleted oxygen levels occur. Gas heaters with a flu and power exhaust are best for greenhouse applications, as they require a hole punched into the side of the greenhouse for the exhaust.

Electric heating is the most efficient, running at 100 efficiency due to the lack of ventilation. However, it is expensive and may not be feasible for many gardeners’ budgets. To offset some of the cost, passive solar heat can be used. If choosing an electric heater, it is best to get a 240V unit with plenty of heat capacity, as they save money and are reliable over the long run. If using a 120V unit, avoid infrared heaters or heaters that transfer heat to objects instead of heating the air.

For greenhouse applications, a heater that heats the air within the greenhouse is necessary. Oil-filled radiator-style heaters are the best inexpensive 120V heaters for greenhouses, which can adequately heat small hobby greenhouses during winter months when placed near a fan.

In summary, greenhouse hobbyists need to consider both gas and electric heating systems to maintain their greenhouses year-round. Gas heating is the most cost-effective option, while electric heating offers more efficiency and reliability.

When can I start using an unheated greenhouse?

It is recommended that the growing season commence in an unheated greenhouse during the late winter to early spring period, typically 4-6 weeks prior to the average date of the last spring frost. For example, if the last frost date is estimated to occur around May 1st, it would be advisable to commence utilisation of the greenhouse in mid to late March. During this period, the greenhouse provides an environment conducive to optimal growth.

Is an unheated greenhouse worth it?

Unheated greenhouses can be beneficial for plants and equipment, as they offer more options than those with built-in controls. It’s essential to understand what can and cannot be done in your greenhouse to use it properly. The structure can be more than just a growing space, even in harsh conditions. There are many options available, such as using extra lights or positioning the space correctly. It’s important to know what you can and cannot do in your greenhouse to maximize its potential.