Just like any product, there is a wide range of costs, depending on how basic you’re willing to go or whether bells and whistles promise to make your life easier. In general, the home advisor website estimates that building a traditional greenhouse will cost just under $10,000. Yet, it can range between $7500 to $28,000 for the materials and construction costs could add between $3,500 and $35,000 to your budget.
Traditional Greenhouses
For small custom greenhouses between 500 sf and 1000 sf, the price averages about $25 per square foot. Of course, that depends on the materials you choose, details of your design, specific location, as well as any upgrades you include.
Hoop House greenhouses are semicircular frames, typically covered with a flexible plastic, with access through the openings on the end walls. These usually run between $5 to $10 per square foot. The frames are generally sold alone, and so may appear deceptively cheap. Keep in mind that the covering must be purchased and installed separately, as well as lighting, watering, and ventilation systems.
Commercial greenhouses have a much lower cost per square foot, but those greenhouses are typically large, between 6,000 and 10,000 sq feet. With a steel framework, a high quality cover, plus fans and a watering system, you’ll be looking at a minimum of $2 to $4 per square foot. Like most things, the more greenhouses you purchase, the lower your unit price will likely be. If you’re really going all in, for example, greenhouses on the scale of an acre (just under 45,000 sq feet) could run from $40,000 to $100,000 or more.
Added Expenses
Adding a heater to a greenhouse can increase your price tag, whether it’s $50 for a cheap space heater or $2000 or more for a more elaborate setup with thermostats and automated controls. On top of this, you’ll need to account for energy bills and appropriate safety measures to avoid the danger of fire, carbon dioxide, or other inherent risks.
Geothermal Greenhouses
Geothermal greenhouses, sometimes known as Walipini or simply pit greenhouses, are fairly simple structures built partially into the ground, and generally considered well suited to DIY enthusiasts. Assuming that the pits are dug manually, the primary cost will be materials for the frame and cover as well as for useful details like doors, steps, benches and lights. Estimates range between $6 and $12 per square foot. Walipinis are widely acknowledged as the least expensive greenhouse type to build, although care must be taken during construction to ensure earthen walls are stable and possibly reinforced. Take time as well to consider slopes and placement so you can avoid common pitfalls like flooding during heavy storms.
Efficiency = Lower Costs
A structure built haphazardly, using cheap materials, stops being a success as soon as you realize it can’t be used as intended. Your greenhouse is no different. Taking time to optimize efficiency at the outset will lower your operational costs so you can reach your break-even point ahead of schedule.
Insulation
Since warmth is the primary driver of your profit engine, optimizing greenhouse insulation is an obvious place to begin.
- Reduce infiltration. Some greenhouses are built with natural gaps in the skin to allow potentially dangerous gasses to escape - such as those associated with combustion heating. However, if you’re using an entirely passive system or a few electric devices, you’ll want to make sure those gaps are closed.
- Invest in retractable energy curtains if your budget permits. These insulated coverings can be spread to blanket the greenhouse at night, reducing heat loss. Even during the summer, curtains can be used to provide shade and keep the interior cool.
- If your greenhouse is aboveground and you’re using a geothermal battery system to store heat from the day, it makes sense to insulate the soil around the greenhouse to keep warmth from conducting out to colder surrounding soil. Soil insulation may be a simple matter of burying sheets of rigid foam insulation around the perimeter of the greenhouse, to the depth of the lowest geothermal tubes.
Other Efficiencies
- Plan to make efficient use of your growing space. The trouble and expense of building an additional greenhouse isn’t worth it if you could get away with reconfiguring the layout and improving workflow.
- Install automated thermostats to switch between heating/cooling and keep the greenhouse within the optimal range. There’s no point in running your heat pump 24/7 if your greenhouse sits safely between the cold/hot limits 12 hours of the day. This kind of initial expense can quickly pay for itself.
