What is the best CO₂ level for a greenhouse?

The VentPlus greenhouse configuration holds a user-settable enrichment band of 400–2,500 ppm. The CO₂ generator tops the air up whenever the level falls to the 400 ppm lower limit, and the ventilation fan vents the excess above 2,500 ppm. Within this band, yield gains of 20–30% from CO₂ enrichment are well documented for most greenhouse crops, including tomatoes, cucumbers and lettuce.

Why does CO₂ drop inside a greenhouse during the day?

During peak photosynthesis on a bright morning, a healthy crop can pull CO₂ below outdoor levels — sometimes as low as 100–250 ppm in an airtight greenhouse. This starves the plants exactly when light is at its best, slowing growth and reducing yield.

How does VentPlus control CO₂ in a greenhouse?

VentPlus has two relays. One controls a CO₂ generator — which turns on when CO₂ falls to the lower limit of your enrichment band (400 ppm) and off once the level recovers. The other controls a ventilation fan — which turns on when CO₂ rises above the upper limit (2,500 ppm) and vents the excess. Both thresholds are user-settable.

Can VentPlus be used as a mushroom farm CO₂ controller?

Yes. VentPlus is widely used as a mushroom farm CO₂ controller across India. It maintains the precise CO₂ range needed at each growth stage — low CO₂ for pinning, moderate for fruiting body development, and higher tolerance during mycelium colonisation.

Does VentPlus work in polyhouses and vertical farms?

Yes. VentPlus is used in greenhouses, polyhouses, vertical farms, and plant nurseries across India. It is plug-and-play, requires no electrician, and works with existing ventilation fans and CO₂ generators via its built-in AC relay sockets.

VentPlus for growers

A greenhouse has
the opposite problem

CO₂ Monitor & Controller for Greenhouses, Polyhouses and Mushroom Farms

For people, CO₂ is a problem to remove. For plants, it's food — and inside a closed greenhouse or polyhouse on a bright morning, a healthy crop can pull the CO₂ level in the air below outdoor CO₂ levels within hours. Growth stalls exactly when light is at its best, and like all CO₂ problems, it's completely invisible.

ISO 9001:2015 Certified Manufacturer Designed & Made in India 1-Year Warranty

VentPlus

Healthy Air, Healthy Life

FAN
ON

CO2 level (PPm)📶 R

1800

06:00 Hr

Good

Range

400–3500

Temp: 31°C Gen<400 Vent>2500

► Holding — both idle

CO2 MONITOR & CONTROLLER

ESCINCRDECRNEXTSEL

AUTOOFFON

OFF

CO2
Generator

OFF

Ventilation
Fan

AUTOOFFON

400ideal band 400–25003500

In the ideal range

CCSunrise. The greenhouse sits in the ideal 400–2,500 ppm range — both relays are off.

start · sunriseone simulated dayend · night

Set levels on this unit CO₂ generator On: 400 ppm CO₂ generator Off: 2,200 ppm Fan On: 2,500 ppm Fan Off: 2,300 ppm

< 400 ppm Depleted — photosynthesis slows, the generator tops CO₂ up

400 – 2,500 ppm Enrichment band — held automatically, yields can rise 20–30%

> 2,500 ppm Too high — wasted gas, the ventilation fan vents the excess

Starving in plain sight

When the canopy pulls CO₂ below outdoor levels, photosynthesis slows, growth cycles drag, and produce comes out smaller and lighter — all without a single visible symptom on the plant.

Enrichment without measurement cuts both ways — too little wastes the opportunity, too much wastes the gas.

What depletion costs you

Slower growth cycles

Smaller, lighter produce

Inconsistent quality between batches

What excess CO₂ levels cost you

Wasted gas if enrichment runs blind

Higher running cost with no extra yield

Bumper harvest —
what steady CO₂ delivers

Commercial growers enrich because it works. The gains compound across every growing cycle:

Yield per cycle

+20–30%

Growth rate

Faster cycles

Crop quality

Consistent

Fuller produce

More photosynthesis means more biomass — bigger fruit, denser leaves.

Predictable batches

A held set-point removes the biggest invisible variable between cycles.

Gas used only when needed

Enrichment without waste — you pay for yield, not for gas that escapes through the vents.

Greenhouses Polyhouses Mushroom farms Vertical farms Plant nurseries

Same instrument, opposite job: feed the crop, don't starve it.

See the research on CO₂ & Greenhouse Yield

The VentPlus solution

The CO₂ monitor & controller for greenhouses —
maintain the CO₂ level that your crop wants

VentPlus CO₂ Monitor & Controller for greenhouses has two relays — 1. for ventilating the greenhouse (bringing outside air into the greenhouse to cover the CO₂ level deficit), 2. to turn on a CO₂ generator (a gas torch) to enhance the CO₂ level. It continuously measures CO₂ and switches on either the fresh-air fan or the CO₂ generator to maintain the CO₂ level in the greenhouse within a user-settable range. Works in greenhouses, polyhouses, vertical farms, and plant nurseries. Plug and play CO₂ controller with two relays.

No wasted gas, no stressed crop. All limits are user-settable.

VentPlus CO₂ monitor and controller in a greenhouse — live CO₂ reading shown on the unit and on the remote dashboard beside a row of tomato plants — The VentPlus controller switches dosing and ventilation equipment through settable CO₂ thresholds.

Continuous monitoring

Real-time CO₂ tracking right at the canopy, all day.

Ventilation fan — when above the desired range

When CO₂ rises above the upper limit of your desired range (2,500 ppm), the ventilation fan turns on automatically — venting the wasteful excess and drawing in outside air until the level is back inside the band.

CO₂ generator — when below the desired range

When the crop pulls CO₂ down to the lower limit of your desired range (400 ppm), VentPlus switches on the CO₂ generator until the level climbs back into the desired range — so the canopy is never starved of the gas it grows on.

Why a greenhouse is the opposite of a room

In an office you fight to get rid of CO₂. In a greenhouse the job is reversed — because your plants are eating it.

In an office or home

People make CO₂

Every breath adds carbon dioxide, so indoors the level keeps climbing. The job is to get rid of it.

CO₂ rises ↑ → vent it out

In your greenhouse

Plants eat CO₂

Photosynthesis pulls carbon dioxide out of the air, so in a closed greenhouse it keeps falling — the opposite problem. The job is to keep it topped up.

CO₂ falls ↓ → add more

The three zones the controller watches

Everything VentPlus does is about keeping the reading inside the ideal band — and pulling it back if it drifts out either side.

below 400 ppm

Below target

Plants are short of CO₂ and leaving yield on the table. The CO₂ generator switches on to lift the level back into the band.

400 – 2,500 ppm

Ideal range ✓

The enrichment band for strong, steady growth. VentPlus works to hold the reading here all day.

above 2,500 ppm

Too high

No extra growth — just wasted gas and money. The ventilation fan switches on to bring in fresh air until it’s back in the band.

Two sockets, two opposite jobs

Plug your equipment in, set the switches to AUTO, and VentPlus does the rest.

🔥 Left socket · CO₂ Generator

Adds CO₂ when the air runs low

When the reading falls to 400 ppm, VentPlus powers the left socket to run your CO₂ generator, then switches it off once the air is back in the ideal band.

Turns ON below 400 ppm
Turns OFF once back in range
Keeps cycling through the day, because plants keep eating CO₂
The ON limit can be set by you to suit the crop you are growing — anywhere in the 400–5,000 ppm range

🌀 Right socket · Ventilation Fan

Brings in fresh air when it runs high

When the reading climbs above 2,500 ppm, VentPlus powers the right socket to run your ventilation fan, drawing in outside air until the level is back in the band.

Turns ON above 2,500 ppm
Turns OFF once back in range
Vents the wasteful excess so you don’t pay for gas that escapes
The ON limit can be set by you to suit the crop you are growing — anywhere in the 400–5,000 ppm range

What a day looks like

The same sequence you can watch on the device at the top of this page — no apps, no manual dosing.

Sunrise

Crop wakes, CO₂ starts fallingPhotosynthesis begins pulling CO₂ down. both sockets idle

Morning

Drops to 400 ppmThe reading hits the lower limit. CO₂ generator ON — dosing up

Midday

Held in the ideal bandGenerator cycles on and off as the crop feeds hardest. generator cycling

Afternoon

A top-up runs past 2,500 ppmThe level goes too high. ventilation fan ON — fresh air in

Evening

Feeding slows, level settlesVentPlus keeps holding the range. both sockets idle

Real-Time and Historical CO₂ Monitoring
From Anywhere

Keep an eye on your greenhouse CO₂ enrichment levels live from your phone, tablet or laptop. The online VentPlus dashboard logs real-time and historical CO₂ data for every zone, so you can confirm the crop is holding the target enrichment band around the clock — and spot problems before they cost you yield. The chart below shows how VentPlus keeps CO₂ within the desired range instead of letting it swing.

monitor.ventplus.in — VentPlus CO₂ Monitor

VentPlus Greenhouse · Zone 1 LIVE

CO₂ now

1,650

ppm

In ideal band

Temperature

°C

Humidity

% RH

Time in band

% of 24 h

Generator

AUTO

5.1 h run

Ventilation

AUTO

1.9 h run

CO₂ level — last 24 hours

CO₂ level Ideal band 400–2,500 Generator on Ventilation on

⤢ Tap the chart to enlarge — then zoom & pan inside

VentPlus remote monitoring website — same interface works on mobile, tablet and desktop

CO₂ Control for Mushroom Farms

Mushroom cultivation is uniquely sensitive to CO₂ — more so than any other crop. Unlike plants, mushrooms produce CO₂ and are harmed by excess of it. Each growth stage has a precise CO₂ requirement, and missing that window means poor yield, stunted pins, or open caps.

VentPlus is widely used as a mushroom farm CO₂ controller across India. The NDIR CO₂ sensor measures carbon dioxide continuously, and the relay switches your exhaust fan on or off to maintain the exact ppm range your mushrooms need at each stage:

Pinning stage

Low CO₂ (500–800 ppm) triggers fruiting body initiation. VentPlus ventilates aggressively to keep levels low and pins coming.

Fruiting body development

Moderate CO₂ (800–1,200 ppm) supports healthy stem and cap development. VentPlus holds the band with automatic ventilation control.

Mycelium colonisation

Higher CO₂ tolerance (commonly 5,000–20,000 ppm) is acceptable here. VentPlus monitors and alerts — intervening only when needed.

Used in polyhouse mushroom farms, container farms, and dedicated spawn rooms across India — VentPlus gives growers precise, automatic CO₂ control for every stage of the mushroom life cycle.

Read the full mushroom farm CO₂ guide

A greenhouse hasthe opposite problem