Grow room climate refers to the overall environmental conditions inside your indoor cannabis grow space — including temperature, humidity, airflow, and CO₂ levels. These factors directly influence how your plants grow, feed, breathe, and defend themselves from stress.

If your grow room is too hot, too dry, too humid, or poorly ventilated, your plants will struggle — even if your lighting and nutrients are perfect.

When we talk about grow room climate, we’re looking at:

• Temperature – the warmth of the air around your plants (ideal: 70–85°F depending on stage)
• Humidity – the moisture content in the air (ideal: 55–65% in veg, 40–50% in flower)
• Airflow – how well air moves through the space to prevent hot spots and mold
• CO₂ – the level of carbon dioxide available to fuel photosynthesis
• VPD – Vapor Pressure Deficit, the balance between temp and humidity that affects nutrient uptake

These factors work together, not in isolation. A perfect temp with bad humidity = problems. Great airflow but poor CO₂ = limited growth.

Poor climate control can lead to:

• Slow growth
• Weak stems
• Bud rot or mold
• Nutrient lockout
• Pest infestations
• Reduced yield and quality

Even small imbalances can cause stress that shows up in your leaves, roots, and buds.

Whether you're growing a few plants in a tent or running a full room, getting your climate dialed in is just as important as your lights and nutrients. It’s the difference between surviving and thriving.

A healthy environment makes everything else work better — from nutrient uptake to resin and terpene production.

Use these free tools to monitor and optimize your grow room climate:

• VPD Calculator
  → Find the perfect temp/humidity balance for each stage

• BTU & CFM Calculator
  → Size your cooling system and ventilation setup properly

• Temp & Humidity Log
  → Track trends and spot problems before they hurt your plants

Grow room climate is the foundation of indoor cannabis cultivation.
When your environment is dialed in, your plants grow faster, feed better, and produce bigger, healthier buds.

Whether you're just starting out or scaling up, mastering climate control is one of the smartest moves you can make.

The ideal temperature range for cannabis depends on what stage of growth your plant is in. In general, cannabis thrives between 70–85°F (21–29°C) when lights are on, and around 65–75°F (18–24°C) when lights are off.

But the sweet spot changes depending on whether you're in veg, flower, or late flower — and whether you're supplementing with CO₂.

Keeping your grow room in the right temperature range helps:

• Fuel photosynthesis and growth
• Prevent heat stress or cold shock
• Improve nutrient uptake
• Reduce mold and mildew risk
• Enhance terpene and cannabinoid production

Too hot? Expect wilting, stretching, or foxtailing.
Too cold? Expect slow growth and purple stems.

If you’re supplementing with CO₂ (above 1000 PPM), you can safely raise your daytime temps to 85–88°F (29–31°C) — but only if your humidity and VPD are also balanced.

► Use the CO₂ Supplementation Calculator to find your ideal CO₂ level and see if higher temps are worth it.

• BTU & CFM Calculator
  → Helps you size your AC and ventilation to keep temps stable.

• Temperature & Humidity Log
  → Track your daily readings and spot trends before they cause problems.

• VPD Calculator
  → Match temp and humidity for better nutrient uptake and faster growth.

Keeping your grow within the ideal temperature range requires tools that help you monitor, heat, cool, and automate your climate.

• Digital Thermometers
  → Track day and night temps accurately

• Inline Fans & Ventilation Kits
  → Remove hot air and bring in fresh cool air

• Grow Room Heaters
  → Prevent cold temps during lights-off or winter grows

• Air Conditioners
  → Cool down your tent during high-heat days

• Climate Controllers & Timers
  → Automate temperature adjustments based on setpoints

• Oscillating Fans
  → Improve airflow and prevent heat pockets

Cannabis grows best in the 70–85°F range, with slight changes based on stage and setup.
Staying in the right zone helps your plants stay healthy, grow fast, and produce top-shelf buds.

Humidity is the amount of water vapor in the air around your plants. In a cannabis grow room, it's one of the most important environmental factors you can control — right alongside temperature and light.

Get it right, and your plants grow fast, feed efficiently, and resist disease.
Get it wrong? You’ll deal with slow growth, mold, and nutrient lockouts.

Humidity determines how quickly water evaporates from your plants’ leaves (a process called transpiration). That evaporation is what pulls nutrients up from the roots.

Too much humidity = poor transpiration, nutrient lockout, and mold
Too little humidity = over-transpiration, calcium deficiencies, and wilting

Here’s the sweet spot for each phase of the cannabis life cycle:

Keeping humidity in range can be tricky, especially as temp and watering rates change. These tools help:

• VPD Calculator
  → Balance humidity and temperature for optimal transpiration

• Dehumidifier Sizing Tool
  → Figure out the right dehu size for your grow room

• Temp & Humidity Log
  → Track trends and spot mold risk before it strikes

Humidity affects how your plants absorb nutrients and resist mold. These tools help you stay in the sweet spot at every stage:

• Digital Hygrometers
  → Monitor humidity levels accurately

• Humidifiers
  → Raise RH during seedling and vegetative stages

• Dehumidifiers
  → Lower humidity during flower to prevent mold

• Inline Fans & Exhaust Systems
  → Remove excess humidity and heat

• Climate Controllers
  → Set RH targets and let your gear adjust automatically

• VPD Monitors or Charts
  → Keep temp and humidity in balance for healthy growth

Humidity control is essential for healthy cannabis plants.
It affects how your plants drink and feed — and it’s your first line of defense against pests and mold.

When in doubt, monitor RH daily, adjust based on your plant’s stage, and use tools to stay consistent.

In a cannabis grow room, temperature and humidity are connected — they affect how your plants breathe, feed, and grow. You can’t adjust one without impacting the other.

That’s why growers use VPD (Vapor Pressure Deficit) to find the balance between the two.

VPD is a measurement of the drying power of the air — basically, how much moisture your plant can release through its leaves.

• Too high VPD = too dry = stress, wilting, calcium issues
• Too low VPD = too humid = slow growth, mold risk

When temp and humidity are in sync, plants transpire properly, pull up nutrients, and grow fast. Off-balance? Growth slows or stops.

Here’s a simplified chart showing ideal VPD ranges for each phase of growth:

• VPD Calculator
  → Plug in your current temp + humidity to see if you're in the zone

• Temp & Humidity Log
  → Track trends and adjust over time

• BTU & CFM Calculator
  → Make sure your ventilation keeps your VPD stable

These tools help you dial in VPD, temperature, and humidity more precisely — and keep your grow room environment stable:

• Digital Hygrometer & Thermometer
  → Instantly check temp and RH inside your tent

• VPD Chart or Monitor
  → See if your grow is in the optimal zone at a glance

• Inline Fans & Ducting Kits
  → Control airflow and exhaust excess heat and humidity

• Dehumidifiers
  → Reduce RH in flower and prevent mold

• Humidifiers
  → Boost humidity in veg or dry climates

• Climate Controllers & Timers
  → Automate your environment for less daily babysitting

Temperature and humidity work together — not separately.
VPD helps you understand how your environment actually feels to your plants, so you can make smarter adjustments.

When temp and humidity are in sync, your plants thrive. When they’re not, problems sneak in fast.

Temperature isn’t just about comfort — it directly affects how your cannabis plants grow, feed, and flower.

When temps are in the ideal range, your plants:

• Transpire efficiently
• Take up nutrients properly
• Build strong structure
• Produce more resin and cannabinoids

But when temps swing too high or too low? You’ll start to see slow growth, stress symptoms, or even crop loss.

Here’s how temperature extremes impact your plants:

• Too Hot (above 85–88°F / 29–31°C)
  → Wilting, heat stress, foxtailing buds, terpene loss, reduced potency

• Too Cold (below 65°F / 18°C)
  → Slow growth, nutrient lockout, purpling stems, weak structure

• Big Day/Night Swings (over 15°F difference)
  → Stress and stunted metabolism

To maintain the right temperature in your grow room, you’ll need the right equipment and smart tools to guide your setup:

• Digital Thermometers
  → Track temperature accurately, day and night

• Inline Fans & Exhaust Kits
  → Remove heat and bring in fresh air

• Heaters
  → Prevent cold temps during lights-off or in winter

• Air Conditioners
  → Cool your grow space during hot seasons

• Climate Controllers
  → Automate temperature regulation for consistent results

• Oscillating Fans
  → Improve circulation and eliminate hot spots

Use these free grow room calculators from GrōHaus to take the guesswork out of climate control:

• BTU & CFM Calculator
  → Estimate how much cooling and airflow you need based on your light wattage and room size

• Temperature & Humidity Log
  → Track and maintain optimal temperature by stage

• Exhaust Fan Timing Estimator
  → Automate fan cycles for better energy efficiency

Temperature is one of the most powerful levers in your grow.
It affects everything from how your plants feed to how strong they smell and how potent they end up.

Keep it in the sweet spot for each stage, and you’ll grow faster, harvest more, and run into fewer problems along the way.

Humidity isn’t just a background number — it has a massive impact on how your cannabis plants grow, feed, and defend themselves.

From seedlings to late flower, keeping your RH (relative humidity) in the right range helps your plants:

• Transpire properly
• Take up nutrients efficiently
• Build strong cell walls
• Resist mold and mildew

Too much or too little humidity can cause problems with growth rate, nutrient uptake, and mold resistance — making it one of the most important environmental variables to control in your grow room.

Here’s what happens when RH is too high or too low:

✘ Too High (Especially in Flower)

• Mold, bud rot, and powdery mildew
• Weak transpiration = poor nutrient uptake
• Stretchy, airy buds

• Stunted growth
• Leaf curling or clawing
• Over-transpiration = nutrient burn or lockout

• Digital Hygrometers
  → Monitor RH and temperature in real time

• Humidifiers
  → Raise RH during early stages or dry climates

• Dehumidifiers
  → Lower RH in flower and prevent mold

• Inline Fans & Exhaust Kits
  → Remove humid air and improve airflow

• Carbon Filters
  → Control odor while exhausting humid air

• Climate Controllers
  → Automate RH adjustments with sensors

Use these free tools from GrōHaus to optimize your humidity planning:

• VPD Calculator
  → Find your ideal temp/RH combo for healthy transpiration

• Temp & Humidity Log
  → Track RH by stage and spot trends before issues arise

• Dehumidifier Sizing Tool
  → Find the right dehumidifier based on space and watering rate

• Exhaust Fan Timing Estimator
  → Automate your air exchange for humidity control

Humidity is one of the most overlooked — but most important — pieces of your grow room environment.

Keep it dialed in by stage, and you’ll avoid mold, boost nutrient uptake, and grow healthier, more potent plants.

When temperature or humidity fall outside the ideal range, your plants will start to show stress — often in their leaves, stems, or overall growth rate. Learning to recognize these warning signs early can prevent bigger problems later.

Here’s how your plants might react to temperature or humidity issues:

Sometimes your environment may look fine, but VPD (Vapor Pressure Deficit) tells a different story. If your temp and humidity aren’t balanced, your plants may be over- or under-transpiring — even if you don’t see damage yet.

Use the VPD Calculator to find your ideal range by stage.

• Digital Thermometers & Hygrometers
  → Spot issues by comparing day/night temp and RH

• Climate Controllers
  → Automate your gear and set alerts for bad ranges

• Oscillating Fans
  → Eliminate hot spots and improve airflow

• Heaters & AC Units / [/collections/air-conditioners]
  → Adjust the climate as needed based on your grow space

• Humidifiers & Dehumidifiers / [/collections/dehumidifiers]
  → Keep RH in the target zone for each stage

Use these free grow room calculators from GrōHaus to help diagnose or prevent climate issues:

• VPD Calculator
  → See if your temp + humidity are balanced

• Temp & Humidity Log
  → Track patterns and fluctuations across your grow

• Exhaust Fan Timing Estimator
  → Improve airflow and reduce RH automatically

• BTU & CFM Calculator
  → Make sure your fans and cooling system are powerful enoug

Your plants are constantly giving you feedback — and climate stress is usually the first thing they complain about. Learn what these symptoms mean, and you’ll catch problems early, save your yields, and grow healthier cannabis with less guesswork.

If you're not actively tracking temperature, humidity, and VPD, you're essentially growing blind. These three variables directly affect how your plants grow, feed, and defend themselves throughout each stage.

Temperature and humidity affect everything from nutrient uptake to mold risk. Vapor Pressure Deficit (VPD) is the relationship between the two — and it tells you how efficiently your plants are transpiring.

When your VPD is in the right range, your plants grow faster, take in nutrients properly, and resist stress.

Here’s what to use for accurate, consistent climate tracking:

• Digital Hygrometer-Thermometers

→ Track temperature and relative humidity in real time. Place one at canopy level and another near the root zone for full coverage.

• Data-Logging Sensors

→ Sensors that store data over time let you see trends like day/night swings or stage-by-stage changes. Many models export to your phone or computer.

• Infrared Thermometer (Optional)

→ Use this to spot-check leaf surface temperature, which impacts VPD and can help detect hidden heat stress.

VPD can’t be measured directly — it’s calculated using your air temperature, relative humidity, and optionally your leaf temperature.

Instead of doing the math manually every day, use tools like:

• GrōHaus VPD Calculator
• Climate controllers with VPD mode

These tools give you recommended humidity ranges based on your current temp and growth stage.

• Place your sensors at canopy height, where your plants are most sensitive.
• Log temperature and RH at least twice daily — once during lights-on, once during lights-off.
  
• Use the same tools throughout your grow, so your data stays consistent.
• Compare your readings to your target VPD range for each stage.

Pro Tip: Use our Temp & Humidity Log to track patterns and fluctuations across your grow

• Digital Hygrometers & Thermometers
• Climate Controllers
• Inline Exhaust Fans & Ventilation Kits
• Smartphone-Compatible Sensors

Monitoring your grow room climate is non-negotiable if you want consistent yields and healthy plants. With the right tools and a little daily tracking, you can stay ahead of issues and keep your environment dialed in from seed to harvest.

Plants thrive in a stable environment — and maintaining the right temperature and humidity is essential for healthy growth, strong yields, and disease prevention. But your grow space won’t stabilize itself. The right equipment gives you control.

Fresh air and proper airflow are the foundation of environmental control.

• Inline Exhaust Fan — pulls out hot, stale air and reduces humidity
• Carbon Filter (optional) — cleans air before it exits your space
• Oscillating Fans — eliminate hot spots and prevent mold by moving air across leaves
• Ducting — connects your fan to the outside or another room for proper airflow

Your lights and environment will raise or lower temps — you’ll need to adjust accordingly.

• Air Conditioner — cools the space and lowers humidity
• Grow Tent Heater — keeps temps stable during lights-off or in colder months
• Clip-On Fans — help dissipate heat from lights and keep canopy temps consistent
• Thermostat or Controller — automates your heater or AC based on target temps

Relative humidity affects everything from nutrient uptake to mold risk.

• Humidifier — adds moisture to dry environments, especially in veg or seedling stage
• Dehumidifier — critical during flower to prevent bud rot and mold
• Humidity Controller — automates your humidifier/dehumidifier for precision control

You can’t control what you don’t measure — or automate what you’re not tracking.

• Thermo-Hygrometer — shows current temp and RH
• VPD Calculator or Meter — helps balance humidity and temp for optimal transpiration
• Environmental Controller — connects fans, heaters, ACs, humidifiers, and more
• Smart Sensors — send alerts and logs via Wi-Fi or Bluetooth

• Inline Fans & Ventilation Kits
• Heaters & Air Conditioners
  
• Humidifiers & Dehumidifiers
• Climate Controllers
• Thermo-Hygrometers & Sensors

Need help figuring out the right temperature, humidity, airflow, or CO₂ levels for your space? These free tools make it easy.

• BTU & CFM Calculator – Estimate how much cooling and airflow your space needs
• VPD Calculator – Find the ideal humidity for your current temperature and growth stage n_with
  auto_awesome save_alt content_copy delete
• Temp & Humidity Log – Track your readings and stay in range from seed to harvest
• CO₂ Calculator – Calculate how much CO₂ to add for stronger growth in sealed rooms
• Dehumidifier Sizing Tool – Get the right size unit based on your watering rate and space
• Exhaust Fan Timing Tool – Set up your fan cycles for efficient ventilation

→ Visit the Environmental Calculators & Tools Suite

Your plants can’t thrive unless your environment is dialed in — and that won’t happen without the right tools. Start with ventilation, then dial in temperature and humidity as needed. Once you've got the basics, automation and measurement tools will help you keep everything stable without constant babysitting.

Once your fans, humidifiers, and heaters are in place, the next step is automation. With the right devices, you can monitor your climate in real time and trigger adjustments automatically — even when you're not around.

Keeping your environment stable is key to consistent growth. But temps and humidity naturally fluctuate throughout the day. Manual adjustments can only take you so far.

Automation keeps your climate in the right range — without constant checking or guesswork. It helps prevent issues like heat stress, mold, or stalled growth before they start.

These devices monitor temperature and humidity around the clock. Many models log data and send alerts to your phone when something goes out of range.

• Great for tracking trends over time
• Use multiple sensors to monitor canopy and root zones

These plug-and-play units connect to your fans, humidifiers, heaters, and AC units. Set your target temp and humidity — and the controller takes care of the rest.

• Automatically turns devices on/off
• Some include VPD presets or mobile apps

Instead of just reacting to temp or RH, these tools calculate VPD in real time and adjust your environment accordingly.

• Ideal for maintaining optimal transpiration
• Some models control both temperature and humidity to stay within target VPD range

• Mobile App Integration – Monitor and adjust remotely
• Data Logging – Track your environment over time
• Multi-Device Support – Control fans, heaters, humidifiers, and more from one hub
• Alarm Settings – Get alerts for high/low temp and humidity

• Climate Controllers & Automation Tools
• Thermo-Hygrometers & Smart Sensors
• CO₂ Devices & Monitors

Need help figuring out the right temperature, humidity, airflow, or CO₂ levels for your space? These free tools make it easy.

• BTU & CFM Calculator – Estimate how much cooling and airflow your space needs
• VPD Calculator – Find the ideal humidity for your current temperature and growth stage
• Temp & Humidity Log – Track your readings and stay in range from seed to harvest
• CO₂ Calculator – Calculate how much CO₂ to add for stronger growth in sealed rooms
• Dehumidifier Sizing Tool – Get the right size unit based on your watering rate and space
• Exhaust Fan Timing Tool – Set up your fan cycles for efficient ventilation

→ Visit the Environmental Calculators & Tools Suite

Grow tents are designed to help you manage temperature, humidity, airflow, and light more easily. But just setting one up isn’t enough. To get healthy plants and great yields, you’ll need to create the right climate inside the tent — and keep it stable from seed to harvest.

Fresh air is the foundation of a healthy grow tent environment.

• Inline Exhaust Fan – Removes hot, stale air and pulls in fresh air passively
• Oscillating Fans – Circulate air inside the tent to prevent hot spots and mold
• Passive Intake Vents or Ducting – Ensure air is flowing in as it’s being pulled out

→ Pro Tip: Your exhaust fan should exchange the entire volume of air in your tent every 1–3 minutes.

Cannabis likes it warm, but not too hot. Lights, seasons, and even the room your tent is in can affect temperature.

• Ideal Range: 70–85°F (21–29°C) during lights-on, a few degrees cooler at night
• Too Hot? Add an AC, stronger exhaust fan, or run lights at night
• Too Cold? Use a tent-safe heater or heat mat in early stages

Humidity needs change with each stage of growth.

• Too Dry? Add a humidifier or reduce exhaust speed
• Too Humid? Increase airflow or use a dehumidifier

You can’t fix what you’re not tracking.

• Thermo-Hygrometer – Shows current temp and RH
• VPD Monitor or Calculator – Helps balance humidity for optimal growth
• Data Logger or Smart Sensor – Tracks changes and alerts you to problems

→ Use Environmental Tools to calculate BTU, CFM, VPD, and more.

Once you’ve got the basics set up, automation tools make it easier to keep things stable.

• Plug your heater, humidifier, or fan into an environmental controller
• Set your target temp or humidity and let the system adjust automatically
• Use app-connected sensors for alerts and remote control

You’ve got your fans, filters, humidifier, and heater in place. Your temps and humidity are in a decent range. But if you want tighter buds, better terpene profiles, and more consistent results, it’s time to start fine-tuning.

Here’s how to go from “good enough” to dialed in.

Your environment fluctuates throughout the day — and from veg to flower. Tracking helps you understand patterns and catch issues early.

• Use a smart sensor or data logger
• Log temperature and humidity at different times of day
• Monitor VPD (Vapor Pressure Deficit) to stay in the ideal range

→ Use the VPD Calculator to see your current conditions

→ Use the Temp & Humidity Log to track patterns and fluctuations across your grow

The temp and RH at canopy level (where the leaves are) is what matters most — not the air near the top of the tent.

• Place sensors at canopy height
• Use an oscillating fan to prevent microclimates
• In larger spaces, monitor multiple zones

Adjust temp and humidity together to stay in range.

Manual adjustments are fine at first, but they’re hard to maintain. A controller helps regulate conditions automatically.

• Set ideal temp and RH
• Plug in exhaust fans, humidifiers, or heaters
• Some models include VPD tracking and app alerts

→ Tip: Automating even one device can make your whole system more stable.

Plants don’t stop growing when the lights go out — but temps and humidity often shift fast at night.

• Make sure your climate stays within 10°F of daytime temps
• Use a controller or timer for nighttime humidity control

Your plants will tell you when something’s off.

• Leaves taco or curl? Too hot or too dry
• Drooping during lights-on? Could be VPD or root stress
• Powdery mildew or bud rot? Too humid in late flower
• Slow growth? Check for cold root zone or dry air

These tools can help you collect better data, automate your adjustments, and keep your environment more stable:

→ Smart Environmental Monitors

Track temperature, humidity, and VPD in real time — with alerts and data logs you can access on your phone.

• Smart Thermo-Hygrometers
• VPD Monitors & Sensors

Plug in your fans, humidifiers, or heaters and let the controller adjust automatically based on your settings.

• Humidity & Temp Controllers
• Multi-Device Climate Controllers

Upgrade your airflow to improve consistency across the entire grow space — especially at night or between stages.

• Inline Exhaust Fans
• Oscillating Fans

Use these to figure out ideal VPD, CFM, BTU needs, and more based on your space and growth stage.

• Environmental Calculators & Tools

Need help figuring out the right temperature, humidity, airflow, or CO₂ levels for your space? These free tools make it easy.

• BTU & CFM Calculator – Estimate how much cooling and airflow your space needs
• VPD Calculator – Find the ideal humidity for your current temperature and growth stage n_with
  auto_awesome save_alt content_copy delete
• Temp & Humidity Log – Track your readings and stay in range from seed to harvest
• CO₂ Calculator – Calculate how much CO₂ to add for stronger growth in sealed rooms
• Dehumidifier Sizing Tool – Get the right size unit based on your watering rate and space
• Exhaust Fan Timing Tool – Set up your fan cycles for efficient ventilation

→ Visit the Environmental Calculators & Tools Suite

CO₂ (carbon dioxide) is one of the most powerful tools in indoor growing — but only if your environment is already dialed in. It’s something you can use under the right conditions, but it’s typically not a necessity for most home grows.

Here’s what to know before you start using it.

CO₂ helps plants photosynthesize more efficiently, especially under bright lights. When levels are elevated (above 1000 PPM), your plants can:

• Grow faster
• Develop thicker stems and leaves
• Produce bigger yields
• Handle higher temps without stress

Use CO₂ only if all of these are true:

✔ Your temps, RH, and VPD are stable
✔ You’re using high-intensity lights (LED or HID)
✔ Your grow space is sealed or semi-sealed
✔ You want to push for maximum yield

If your climate isn’t stable or your airflow is high, extra CO₂ will just get pulled out before plants can use it.

→ Pro Tip: Stop using CO₂ in the final weeks of flower — it’s not needed and may reduce aroma or trichomes.

To supplement CO₂ safely and effectively, you’ll need:

• CO₂ Source: Tank + regulator, or CO₂ bags for small tents
• CO₂ Controller: Turns injection on/off based on PPM
• PPM Monitor: Tracks levels in real time
• Sealed Space: To prevent your CO₂ from escaping too fast

Shop CO₂ Devices & Monitors →

Use our CO₂ Supplementation Calculator to find out:

• How much CO₂ your space needs
• How often to run your emitter or tank
• If CO₂ is even worth it for your setup

Launch CO₂ Calculator →

CO₂ is safe when used properly — but high levels can be dangerous in sealed rooms if not monitored.

Safety Tip: Always use a CO₂ monitor with alarms if working in a sealed space. High PPM levels can be harmful to humans even if they benefit plants.

→ Do I need CO₂ to grow good cannabis?
No. Most home growers get excellent results without it. Focus on dialing in temp, humidity, and airflow first.

→ Can I just use a CO₂ bag in my tent?
CO₂ bags may help a little in small tents but won’t make a big difference unless your environment is sealed and stable.

CO₂ can boost growth and yield — but only in the right setup.
If you're a beginner or not using high-intensity lights in a sealed room, skip it for now.

Dial in your temp, humidity, and airflow first — then revisit CO₂ when you’re ready to scale up.

This checklist covers the essential gear and tools to help you maintain a stable grow environment — even in a small tent or closet grow.

1. Thermometer & Hygrometer
Track temperature and humidity daily at plant canopy level.
→ Browse Thermo-Hygrometers

2. Inline Exhaust Fan
Pulls hot, humid air out of your grow space to maintain airflow and reduce moisture buildup.
→ Shop Inline Fans

3. Oscillating or Clip-On Fan
Keeps air moving inside the tent to prevent hot spots, mold, and weak stems.
→ See Circulation Fans

4. Humidifier or Dehumidifier
Use depending on your local climate and the time of year. Raise or lower humidity to stay in the right VPD range.
→ Humidity Control Gear

5. Environmental Calculator Tools
Use our free tools to:

→Use the Free Tools

6. Temp & RH Log (Manual or Digital)
Track your temperature and humidity daily so you can catch issues early.
→ Download the Free Log

• Smart Environmental Sensor
Get alerts to your phone if temp or humidity goes out of range.

• Climate Controller
Automatically turn devices on/off based on temperature or humidity targets.

• VPD Chart or Calculator
Helps keep your temp and humidity in balance for optimal plant health.

Start with the basics and build from there. A reliable thermometer, fans, and humidity control go a long way — you can always upgrade to automation later.

Use this chart as your go-to reference for ideal temperature, humidity, VPD, and light cycles at each stage of growth. These ranges help you create the best environment for healthy plants and bigger yields — just match your current stage and adjust as needed.

• Lower RH + higher VPD in late flower helps prevent mold and increase resin production.
• Don’t stress about hitting exact numbers — aim for the target range and adjust gradually.
• If you’re not using CO₂, keep temps on the lower end of these range