Do you want to extend your gardening season? Grow tropical plants in a colder climate? Get a head start on spring plantings? A greenhouse allows gardeners to customize growing conditions year-round but heating it properly is essential.

This comprehensive guide will explore various heating systems, insulation tips, temperature regulation, troubleshooting, and smart practices to create the ideal warm environment in your greenhouse. Follow these tips to keep your greenhouse heat efficient and your plants happily thriving through cold months!

Choosing the Right Greenhouse Heating System

The greenhouse heating system you select should fit the size of your structure and your budget. The main options each have pros and cons:

Electric Heaters

Best for small to mid-sized greenhouses, electric space heaters are inexpensive to install but more costly to run daily. Convection heaters that circulate air prevent cold spots. Consider heavy-duty commercial greenhouse units.

Gas Heaters

Propane and natural gas heaters deliver powerful, consistent warmth perfect for larger greenhouses. Units can be pricey upfront but cheaper to operate than electric. Ensure proper ventilation.

Wood Stoves

Burning wood provides steady radiant heat at a lower cost but requires regular stoking and venting. Central wood stoves must be properly installed and monitored.

Geothermal Systems

Pipes buried underground tap into the earth’s constant warmth for incredibly efficient heating. However, installation fees are quite high for geothermal greenhouse systems.

Solar Heating

Solar greenhouses use sunlight to naturally heat the interior. Passive solar designs have angled glazing to optimize warmth. Active solar uses collectors and fans to distribute heat. Solar heating needs careful insulation.

When choosing a primary heating system, assess your greenhouse size, plant types, climate, budget, and access to fuel sources. Most hobby greenhouses do well with electric or gas heaters for their control and ease of use.

Pro Tip: Insulate the greenhouse tightly to reduce the size heater needed. Seal any leaks around foundations, vents and glazing.

How to Determine the Right Size Heater

A correctly sized heater will maintain the desired temperatures to keep plants thriving. An undersized heater will struggle to warm the space, while an oversized unit wastes energy. Sizing depends on:

• Greenhouse square footage – The total area and volume to be heated.
• Insulation quality – A well-insulated structure retains more warmth and needs less heating power.
• Outdoor climate and seasons – Colder regions and winter months increase heating needs.
• Desired temperatures – The optimal temperature range for the plants grown.
• Heater specifications – BTU ratings for gas heaters, wattage for electric.

To size your heater, calculate the greenhouse volume in cubic feet (length x width x height). Refer to heater manufacturer sizing charts to match the volume with an appropriately powered unit.

Pro Tip: Supplement the primary heater with a secondary unit on extremely cold nights or in large greenhouses.

Optimizing Greenhouse Heat Distribution

Even in a fully heated greenhouse, problems like cold spots or dry crisp plants can occur. Proper heater placement and heat circulation prevents this.

• Mount heaters near the center or highest point to distribute warmth out and down.
• Convection heaters that circulate air prevent cold pockets better than radiant units.
• Focus space heaters on rows where plants need extra warmth.
• Run heaters on low continuously rather than high temporarily for consistent temps.
• Use insulation and thermal sheets around plants to retain heat right where it’s needed.
• Let ventilation fans circulate air so heat doesn’t get trapped near the roof.
• Install thermal curtains to lock in warmth at night and on cloudy days.
• Position heat-loving citrus trees and tropicals near heat sources, cool-weather plants on the perimeter.
• Monitor temperatures at plant level with thermometers. Use a thermostat to control the heater automatically.

With some trial and error, you can achieve evenly distributed, comfortable warmth ideal for your greenhouse plants to thrive in!

Pro Tip: Add space heaters near the door which is often a big source of heat loss as you go in and out.

Best Practices for Efficient Greenhouse Heating

Heating costs can add up quickly in a greenhouse. Follow these tips to save energy and money while keeping optimal temperatures:

• Determine the ideal temperature range for the particular plants you are growing. Cannabis likes 70-80°F, lettuce and kale prefer 55-65°F, for example.
• Research heaters thoroughly and size appropriately before buying. Have a qualified technician install gas heaters or complex systems.
• Insulate extensively. Seal every draft and gap. Use dual-poly sheets, thermal curtains and even bubble wrap to retain heat.
• Use thermostats to precisely monitor temperatures and automatically adjust the heaters. Locate sensors at plant level, not up high.
• Schedule annual maintenance and cleaning to ensure heaters run safely and efficiently over time.
• Incorporate passive solar design like south-facing glazing to maximize free heat from the winter sun.
• Turn heaters off once overnight low temperatures are reached. Allow the sun to warm the greenhouse during the day.
• Have adequate fuel supplies on hand for winter. Check propane tank levels regularly or stock up the woodpile.
• Grow cold-tolerant plants like kale and carrots through colder months when less heating is needed. Grow tender plants like tomatoes in summer.

With some strategic planning, your greenhouse heating system can be green, efficient, and provide the perfect year-round growing environment.

Pro Tip: Install a backup power generator to operate essential heating and equipment during electrical outages.

Troubleshooting Common Greenhouse Heating Problems

Getting your greenhouse heating dialed in can involve some troubleshooting. Here are some frequent issues and solutions:

Problem: Heater constantly runs but can’t reach the desired temperature.

Solution: The heater is too small. Install a more powerful heater.

Problem: Temperature plunges quickly on cold nights.

Solution: Insulate and seal the greenhouse fully. Add a secondary heater. Use thermal curtains.

Problem: Plants closest to heater dry out or get scorched.

Solution: Move plants further away. Improve airflow. Add shading by the heater.

Problem: Loud banging or popping comes from heater.

Solution: Have a technician inspect and repair gas heaters. Replace damaged heaters.

Problem: Heater keeps shutting off unexpectedly.

Solution: Clean clogged air filters. Refuel empty propane or wood heaters.

Problem: Certain spots stay too cold while others overheat.

Solution: Relocate or add additional heaters to cold spots. Improve heat circulation.

Monitor conditions closely and make adjustments to create your ideal microclimate. A few tweaks can get your greenhouse heating running smoothly.

Pro Tip: Keep a greenhouse thermometer and humidity gauge at plant level to easily monitor conditions.

Heating Options for DIY Greenhouses

Handy gardeners building their own greenhouse have many heating options:

• Portable electric heaters – Inexpensive to buy and install but energy intensive for ongoing use. Ensure proper wiring.
• Heating mats – Gentle warmth from below planting beds.
• Heating cables – Line the base of walls with cables for perimeter warmth.
• Chiminea or fireplace – A wood-burning chiminea or fireplace can heat a small DIY greenhouse. Follow all fire safety precautions.
• Wood stove – A wood stove centrally located and properly installed provides steady radiant heat.
• Passive solar – South-facing angled glazing maximizes winter sun warmth. Use thermal mass.
• Cold frames – Tiny cold frame greenhouses can utilize passive solar heat for a few plants.

For small hobby greenhouses, electric heaters, fireplaces, or passive solar gain are inexpensive DIY options. For larger spaces, install a primary HVAC system or wood stove. Focus on quality insulation to retain existing warmth.

Pro Tip: South-facing greenhouses backed by a heat-absorbing brick wall maximize solar warmth from the low winter sun angle.

Conclusion

With the right heating setup, you can customize growing conditions in your greenhouse to keep plants thriving year-round. Careful planning ensures your system provides cost-effective, energy efficient warmth tailored to your plants’ needs. Monitor conditions closely, improve insulation, and implement smart practices to get your greenhouse heating operating smoothly. The investment in an effective system that keeps your greenhouse cozy warm even in winter will extend seasons and bring you joyful greens and blooms despite cold weather!

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