You can use a greenhouse in winter, but the right approach depends on whether it is a passive-solar deep winter greenhouse, a conventionally heated greenhouse, or an unheated high tunnel. Match crops to your light and temperature conditions, reduce avoidable heat loss, and consider whether a cold frame or row cover can meet your needs without heating the whole structure.
Choose the right winter-growing approach
“DWGs are passive-solar greenhouses that use the energy from the sun as the primary source of heat,” explains University of Minnesota Extension. That is a specific design approach, not simply any greenhouse left unheated in winter.
| Structure | How it handles winter | Best fit |
|---|---|---|
| Deep winter greenhouse | Uses passive solar design; UMN describes east-west orientation, steep south-facing glazing, and a fan that moves sun-warmed air underground into insulated soil or rock thermal mass for release at night. | Growers planning a purpose-built passive-solar system, particularly in northern climates. |
| Conventionally heated greenhouse | Uses a heat source and ventilation to manage temperature. Heating and ventilation make reliable electricity important. | Growers whose crops and conditions require supplemental heat, with equipment matched to the structure and local conditions. |
| Unheated high tunnel | Relies heavily on ventilation and crop scheduling; some operations add temporary or permanent supplemental heat. Low midwinter sunlight can still limit growth. | Season extension or production plans that can accommodate winter light and temperature constraints. |
| Cold frame or row cover | Protects plants and captures daytime solar heat without heating a full greenhouse; a cold frame needs daytime venting. | Small gardens or growers who need localized protection rather than a full greenhouse. |
For a northern-climate passive-solar build, UMN identifies The Northlands Winter Greenhouse Manual by Carol Ford and Chuck Waibel as a resource covering construction specifications and production techniques. See UMN’s deep winter greenhouse guidance for details.
What can you grow in a winter greenhouse?
UMN lists lettuces, herbs, brassicas, Asian greens, and sprouts as crops suited to its deep winter greenhouse system. Its guidance emphasizes cold-hardy plants that tolerate minimal light. The list is not a guarantee that every variety will thrive in every winter structure: crop choice needs to reflect the greenhouse’s light, temperatures, climate, and design.
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For a small, unheated cold frame, UMN lists cool-season crops such as lettuce, kale, cabbage, cauliflower, and broccoli for cool-month use. A cold frame’s snug lid helps limit air leakage, but it should be hinged so it can be opened for daytime ventilation. See UMN’s season-extension guidance.
How to manage a conventionally heated greenhouse
A conventionally heated greenhouse needs a winter heat source. Penn State Extension notes that ventilation helps maintain a more constant temperature when heat is not required. Because both heating and ventilation depend on electricity, plan for a reliable supply and consider backup generation. Equipment and settings must suit the structure, crops, and local conditions; there is no universal winter temperature setpoint or heater size for an unspecified greenhouse. Penn State’s greenhouse production guidance discusses these operating needs.
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- 1500W Fast Heating: Electric greenhouse heater heats up in 3 seconds, effectively warming spaces up to 120 sq ft. Perfect as a greenhouse heater for winter plants, protecting vegetables and flowers from freezing
- Versatile Use: Engineered for reliable, worry-free heating in damp environments. This air circulation heater is perfect as a grow tent warmer, or for bringing steady warmth to patios, garages, greenhous, and flower rooms throughout winter. A built-in carry handle allows you to effortlessly move it wherever heat is needed.
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Reduce avoidable heat loss
Before adding heat, address losses and controls. Penn State Extension recommends several measures for greenhouse energy efficiency:
- Look for leaks and seal them where appropriate. Penn State reports that sealing leaks can often reduce heating bills by 5 to 10 percent; actual savings depend on the greenhouse and conditions.
- Consider a movable thermal screen for nighttime. Penn State says screens may reduce heating costs by as much as 30 or 40 percent; this is a potential estimate, not a guaranteed saving.
- Check thermostats and other control systems so they operate as intended.
- Seal fan openings when appropriate for the system and operating conditions.
- Consider perimeter insulation. Penn State reports savings on the order of 5 percent for Pennsylvania conditions, which should not be treated as a universal estimate.
These figures come from Penn State’s guidance on greenhouse energy efficiency. They describe source-reported estimates, not a promise for a particular building.
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- Versatile All-Season Use: Our electric greenhouse heater offers three adjustable power levels: 20W Low, 750W Medium, 1500W High. You can freely switch modes according to environment temperature and your needs. It works perfectly as an outdoor heater for patios and grow tent, a drying aid in garages and workshops, an indoor heating source or a summer cooling fan.
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When you may not need a full greenhouse
If you only need to protect a few beds or extend the growing season, cold frames and row covers can avoid the cost and operating demands of heating an entire greenhouse. UMN describes cold frames as shallow, unheated structures that collect daytime solar heat and protect plants at night. Keep the lid snug to reduce air leakage, and vent it during the day to manage warmth.
An unheated high tunnel can also extend production, but it is not equivalent to a heated greenhouse. Penn State highlights ventilation and crop scheduling, and notes that low sunlight can limit midwinter growth even when a structure is warm. Choose a structure based on the crops and the winter conditions it must handle—not warmth alone.
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- Multi-Scene Application: Whether it's for chick brooding, plant tents, greenhouse insulation, or drying renovations, our heater offers the perfect solution. Suitable for multiple venues, it adds more possibilities to your comfortable life.
- Hot and Cold Modes: The heater can be used all year round, keeping you warm in winter and cool in summer, providing a suitable environment for plants. Easy to operate, the heating mode heats up quickly and evenly, while the ventilation mode cools through a fan. The three-level temperature adjustment knob meets your different usage needs.
Plan for the build and operating costs carefully
UMN Extension’s 2018 analysis of eight Upper Midwest deep winter greenhouse enterprises reported an average construction cost of $18,583, or approximately $33 per square foot. Participants reported a 7.3 percent overall return on investment, variable costs of $35 to $2,148 per crop with an average of $906, and operating revenue of $2.52 per square foot of growing space. The analysis says its eight-participant findings are not statistically significant; they are historical observations from growers trying to make winter greenhouse production commercially profitable, not current projections or guaranteed returns for an individual build. See the UMN winter greenhouse enterprise analysis.
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- IP20 Protection: Made of high-quality, high-hardness alloy steel, it features an IP20 protection design, making it fearless of foreign object intrusion. ETL certified with overheat protection, it ensures safety and peace of mind. This heater provides long-lasting durability, suitable for various humid environments.
- Multi-Scene Application: Whether it's for chick brooding, plant tents, greenhouse insulation, or drying renovations, our heater offers the perfect solution. Suitable for multiple venues, it adds more possibilities to your comfortable life.
- Hot and Cold Modes: The heater can be used all year round, keeping you warm in winter and cool in summer, providing a suitable environment for plants. Easy to operate, the heating mode heats up quickly and evenly, while the ventilation mode cools through a fan. The three-level temperature adjustment knob meets your different usage needs.
- Portable and Lightweight: Our greenhouse heater is thoughtfully designed for easy operation, weighs less than 5 pounds, and comes with a portable handle. It can be adjusted to a 25° angle with a stable anti-slip base, allowing you to move it to different locations for use anytime, anywhere.
- Crop needs: Consider how much light and what temperatures your chosen crops require.
- Site and structure: Account for local winter severity, solar exposure, orientation, glazing, and insulation.
- Energy and reliability: If using supplemental heat or ventilation, plan for dependable power and a backup strategy.
- Labor and monitoring: A winter setup needs appropriate operating attention, particularly when heat and ventilation controls are involved.
- Scale: Decide whether production needs justify a full greenhouse or whether a cold frame or row cover can extend the season.
Before sizing or installing heating equipment, get crop-specific and locally applicable specifications. The right solution depends on location, structure, crop, energy source, and safety requirements.
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