September 09, 2020 7 min read

By George Mouratidis

In terms of climate, marijuana likes it steamy.

This should come as no surprise considering cannabis has thrived for centuries in tropical regions. However, that doesn’t mean there aren’t temps that are too hot for pot.

While cannabis usually won’t die when exposed to excessively high temps, there’s a far greater chance your plants will run into issues like nutrient deficiencies, bud burn, or mold.

Even in the best-case scenario, intense heat often leads to diminished marijuana yields and weak effects. For these reasons, home-growers must know how to reduce their grow tent’s temp.

Thankfully, indoor cultivators have come up with many handy tips to keep their tent's temp stable. But before we get into how to chill your tent’s temp, let’s briefly review the ideal environment for cannabis growth.

What’s A Good Temp For Hemp?

In general, cannabis performs well in warm climates similar to what you’d find in tropical, subtropical, or Mediterranean regions.

It’s usually best to keep your grow space between 70 – 80°F during the day and just a touch cooler at night. Although some strains could “make it” with nighttime temps in the high 60s, it’s usually best to keep your grow tent around the 70°F mark for the best results.

In terms of humidity, most home-growers recommend anywhere from 60 – 70 percent for vegetative plants and 45 – 55 percent during flowering.

The only exception to this rule is if you’re using clones, in which case you need to ramp up humidity levels to the 80 – 90 percent mark. By the way, anyone interested in cloning strains should check out Everything But The Plant’s extensive cloning catalog.

Of course, every cannabis strain has slightly different temp needs. In some cases, growers deliberately expose certain strains to chilly conditions on a few nights to bring out gorgeous purple leaves.

Before you try any of these tricks, however, we recommend doing thorough research on your chosen seeds to find the determine the perfect climate for your grow tent.

How Do I Know My Grow Tent Is Too Hot?

The simplest way to tell whether your grow tent is too hot is to use a high-quality thermometer and hydrometer.

Although you could get a sense for your grow tent’s temp by walking inside every day, the only way to accurately gauge temp and humidity is to monitor levels on these devices.

Beyond using a thermometer and hydrometer, there are a few other warning signs your grow room is getting too hot.

For instance, if you notice your cannabis plant’s leaves curving upwards, then you should think about reducing your grow tent’s heat levels.

Other warning signs of excessive heat include a “rotting” smell, dry soil, bud burn, and a slower-than-average flowering period.

What Can You Do To Cool Your Grow Tent? – Seven Strategies To Consider

Now that you know how crucial climate is for cannabis plants, let’s get into a few of the easiest ways you could bring some chill into your grow tent.

1. Ensure Your Tent Has A Good Exhaust System

The first step to controlling temperature is to make sure your tent has exhaust flaps on the top and bottom. Since hot air rises, the top exhaust helps carry out hot air, while the floor vent primarily brings in cold air.

If possible, you should attach your hot air vent to either a window or chimney to bring the hot air outdoors.

For optimal air circulation, try to keep your vent as straight as possible as it exits your grow tent. Also, be sure to attach a carbon air filter to your exhaust flap if you don’t want nosy neighbors sniffing your ganja goodies.

Luckily for home-growers, exhaust flaps are a standard feature in professional grow tent manufacturing. In fact, all of the grow tents now available on Everything But The Plant have easy-to-use air vents to help cultivators keep fresh air circulating through their grow space.

For more details on our grow tent catalog, be sure to follow this link.

2. Take Care To Examine Your Lighting System

The grow lights you use will contribute the most heat to your grow space. This is especially true in grow tents that have a reflective inner Mylar coating. For this reason, home-growers must research their preferred light’s intensity before making a purchase.

Unfortunately, since every grow light has a different set of specs, it’s difficult to estimate how much heat each model gives off.

While fluorescents tend to give off the least heat, most home-growers don’t use them for the entire growth process. Both HIDs and LEDs give off more heat than fluorescents, but just how much they give off depends on what intensity you’re using.

One thing that’s for sure is that HIDs require more space than LEDs. If you’re living in a home where space is limited, you should focus your search on LEDs rather than HIDs.

Another feature to consider when browsing different grow lights is whether the model you’re looking at has a dimmer option.

Although this feature usually costs more, dimmers offer growers a convenient way to cut your grow room’s temp literally with the flip of a switch. Dimmed lights also better mimic the sunset, which might help increase yields.

To offer cultivators the best choice for their growing space, Everything But The Plant now provides plenty of professional grow lights. Be sure to check out our full grow light catalog on this webpage.

3. Consider A Portable AC Unit Or An Evaporative Cooler

If you’re struggling to keep your grow room temps down with exhaust fans, you might want to consider investing in a professional AC unit.

While this device will increase your energy bill, it remains the easiest way to quickly and reliably cool your grow tent. Plus, many portable AC units now available make temperature control in tight quarters a “breeze.”

Somewhat related to AC units, evaporative coolers are another effective way home-growers could bring down a grow tent’s temperature.

However, anyone who’s planning on using these coolers must remember they will raise humidity levels. Typically, it’s best to use evaporative coolers if you live in a reliably hot and dry climate.

4. Hot Nights, Cool Days – Experiment With A Reverse Light Schedule

One of the most inventive ways home-growers keep their tent’s temps tempered is to reverse their lighting schedule.

Instead of turning your lights on every morning, turn them on before bedtime. Since it’s naturally cooler during the night, there’s less chance your plants will suffer from heat exhaustion compared with the daytime.

As a bonus, running your lights at night could save you some serious ca-ching!

Many cultivators say they’ve successfully used this lighting schedule to reduce their electricity costs. If you are going to use this method, take a close look at your electricity bills and compare them with previous daytime grow cycles.

5. Don’t Boil Your Buds! – A Few Tips For Hydroponics Growers 

If you’re a hydroponics grower, you might already know that hot water could land you into, well, “hot water.”

Reservoir water that has above average temps cannot effectively deliver oxygen or nutrients to your plants. Even worse, hot hydroponics water is a breeding ground for algae and a significant contributor to root rot.

According to most home-growers, the ideal temperature for hydroponics water is between 64°F – 75°F. However, most experienced cultivators urge students to stay closer to the 64°F mark for the best chances of survival.

Here are a few of the simplest ways you could heat-proof your hydroponics water:

  • Occasionally throw a plastic bottle full of frozen water into your reservoir.
  • Paint your reservoir’s surface white to deflect heat.
  • Place the reservoir outside of the grow tent to avoid light exposure.
  • Consider purchasing a water chiller device.

By the way, Everything But The Plant now offers many beginner-friendly hydroponics units with built-in nutrient distribution systems. If you’d like to learn more about our hydroponics offerings, please feel free to visit this link.

6. Do Fans Keep Temperature Cool?

You may have noticed we’ve yet to mention adding fans to your grow tent as a means of keeping temps down.

Although fans play an essential role in air circulation, they won’t necessarily reduce your tent’s temperature.

Although fans could bring your tent’s temps down if it’s colder in the surrounding area, it will only re-circulate hot air if you’re living in a warm climate.

This doesn’t mean, however, that you shouldn’t use fans in your grow tent. Although they aren’t reliable for temperature control, fans offer many other benefits for home-growers.

Most significantly, the gentle breeze fans provide will discourage the growth of mold, mildew, and pests. Portable fans also provide your plants with a bit of mild air resistance, which helps stems grow stronger over time.

7. Is Your Pot Too Hot? Turn To These Supplements

Lastly, there are a few nutritional supplements home-growers should know about to revive cannabis plants suffering from heat exhaustion.

Just keep in mind that these tips are only intended to help plants that are already showing signs of distress. Please don’t rely on these supplements to help your plants survive in a sweltering grow tent.

According to most cannabis growers, kelp extract is the most effective supplement for heat-exhausted plants.

Not only does kelp contain a plethora of healing nutrients, it appears to help plants absorb essential minerals and increases their resilience.

Along with kelp extract, the mineral silica also strengthens the cannabis plant’s resistance to heat.

Adding just a touch of this mineral to your plant’s diet could significantly improve your plant’s cells, leading to a firmer stem structure. Indeed, many home-growers use silica on sativa strains to prevent top-heavy buds from snapping stems.

Believe it or not, it also appears silica may offer a few health benefits for humans when taken as a dietary supplement.

If you’re interested in learning more about silica's potential uses, we encourage you to read through this previous post on Micro Plant Powder.

Control Your Tent’s Temps For Crazy Cannabis Yields

Along with proper watering and nutrition, managing your grow tent’s temperature is essential for a successful cannabis crop. If you begin noticing your tent’s temp veering into the 80°F territory, please try out the tips listed above to keep your cannabis comfy.

For even more info on indoor temperature control, we encourage you to read this previous post.


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