Johnson CO₂ Generator

Do you want bigger yields and better-quality blooms from your greenhouse? Then the Johnson CO₂ Generator can help. It enriches the air with carbon dioxide — the raw fuel plants use to grow. So your crops grow faster, fuller and healthier. Above all, it’s a proven way to lift production, especially through winter. In short, it gives growers spring-and-summer results even in the colder months.

The science here is simple but powerful. Normally, the air holds around 300 ppm of CO₂. However, when you raise that to over 1,000 ppm, plants produce more and grow better. The Johnson CO₂ Generator delivers up to 1,500 ppm per unit in a greenhouse as large as 446m² (4,800 sq ft). As a result, you can unlock significantly stronger growth from the same space.

Why Use a CO₂ Generator

CO₂ is often the hidden limit on plant growth. To start, plants use CO₂ for photosynthesis, so more of it means more growth. In winter, though, growers close their vents to keep heat in. As a result, CO₂ levels inside the greenhouse drop fast as the plants use it up. So growth slows, right when you want your crops thriving.

A CO₂ generator solves this directly. For example, it tops up the CO₂ your plants consume, keeping levels in the productive range. As a result, you get yield and bloom quality more like spring and summer — even in the depths of winter. In short, it turns your sealed winter greenhouse back into a high-performing growing space.

H2: Key Features

• Boosts greenhouse CO₂ up to 1,500 ppm per unit
• Covers a greenhouse up to 446m² (4,800 sq ft) per unit
• Fully automatic operation
• Includes a gas pressure gauge
• 24-volt gas valve
• Automatic shut-off on flame failure for safety
• Easy install — hangs from the ceiling, no ductwork needed
• Compact: 18″ diameter, 20″ high, just ~9.5kg (21 lb)
• Available in natural gas or propane
• Optional timer/thermostat available

H2: Specifications

• Max area per unit: 4,800 sq ft (~446m²)*
• CO₂ output: 72 cubic feet/hr at 60°F
• CO₂ rate: 8.25 lb/hr
• Burner range: 20,000 to 60,000 BTU/hr
• Gas valve: 24-volt
• Fuel: natural gas or propane
• Dimensions: 18″ diameter x 20″ high (~46 x 51cm)
• Weight: ~9.5kg (21 lb)
• Safety: automatic flame-failure shut-off; gas pressure gauge

*Based on adding 1,500 ppm CO₂ with one air change per hour. Slightly less when burning natural gas.

Browse our full greenhouse climate-control range and greenhouse accessories — including controllers, heaters and fans — or speak with our team for help choosing the right setup.

H2: How to Use It

Getting the best from your generator is straightforward. First, run it when there’s sunlight and the vents are closed, since that’s when plants photosynthesise and CO₂ matters most. Then, if you open the vents to release heat, keep the generator running for about two hours before shutting it off. As a guide, roughly 0.45kg (1 lb) of CO₂ per hour per ~930m² (10,000 sq ft) yields about 1,000 ppm. So if levels drop on a clear, sunny day, simply increase the burn rate to keep up with demand. Most growers run theirs daily through winter, from around 7:30am to 4:30pm. Pair it with a CO₂ controller or monitor for precise, automated dosing.

H2: Why Pair It with a Monitor

CO₂ is invisible, so measuring it matters. For example, a CO₂ controller switches the generator on and off to hold your target ppm automatically. As a result, you avoid wasting gas and keep levels in the ideal range. Importantly, it also helps keep CO₂ at safe levels for people working in the greenhouse. So a monitor isn’t just about yield — it’s about safety and efficiency too.

H2: Frequently Asked Questions

What does a CO₂ generator do? It burns gas to release carbon dioxide, raising greenhouse CO₂ levels. So your plants photosynthesise more and grow faster, with higher yields and better blooms.

How much area does one unit cover? Up to 446m² (4,800 sq ft) per unit, raising CO₂ to around 1,500 ppm.

When should I run it? During daylight when the vents are closed. So it’s especially valuable in winter, when low CO₂ limits growth.

Is it safe? It includes an automatic flame-failure shut-off and a gas pressure gauge. Still, because it burns gas and produces CO₂, it must be professionally installed, and a CO₂ monitor is strongly recommended for safety.

What fuel does it use? Natural gas or propane — choose the option that suits your site.

H2: Conclusion

In the end, the Johnson CO₂ Generator is a proven way to grow bigger, healthier, higher-yielding crops — especially through winter. It enriches your greenhouse with CO₂ up to 1,500 ppm, runs automatically, installs easily and includes built-in safety features. Plus, with natural gas or propane options, it suits a range of sites. So browse our climate-control range or get in touch for expert advice today.