Too Hot for Pot? >> The Best Temperature To Grow Marijuana (2022)

Too Hot for Pot? >> The Best Temperature To Grow Marijuana (1)

Marijuana plants can grow and survive practically anywhere regardless of the climate, hence the nickname “weed.” However, they will struggle and likely not produce desirable effects if the temperature is too hot.

The easiest way to prevent heat problems is to select strains that do well in your particular climate. You can also use grow rooms or greenhouses to create ideal environments. However, even if you create a dedicated indoor space, you’ll still need to pay close attention to the temperature. You don’t want it to be too hot for your plants.

Whether you are growing outdoors in Las Vegas or setting up an indoor grow room in Detroit, you’ll need to watch your plants carefully for signs of heat stress. Even in a grow tent, if your marijuana grow tent temperature is too high, your plants will start to have problems.

About Too Hot for Pot?

  • Symptoms of Heat Stress
  • Do marijuana plants stop growing at certain temperatures?
  • How to grow marijuana in extremely high temperatures
  • What is the ideal temperature for growing marijuana?
  • Soil temperature and marijuana plants
  • What marijuana strains grow well in hot temperatures?
  • What about humidity?
  • Fixing and preventing marijuana heat problems

Symptoms of Heat Stress

In general, a sign of heat stress in marijuana plants are curling leaves. Here are some other signs to look out for:

  • Leaf edges that curl upwards
  • Wilted and drooping leaves
  • Burnt leaves with the tips that appear brown
  • Wilting and drooping of the entire plant
  • The development of foxtails. This is where a plant grows a new bud on top of the initial one. Foxtailing often occurs during the flowering stage.

Too much heat can be a real problem. When marijuana plants are exposed to extremely high temperatures, they are susceptible to:

  • spider mites
  • root rot
  • nutrient burn, which is as a result of increased water transpiration
  • white powdery mildew, which is a result of too much humidity
  • Wilting, which is a result of lack of enough oxygen
  • Buds that lack smell. This because terpenes burn away at high temperatures
  • Increased stretching

Do marijuana plants stop growing at certain temperatures?

The good news is marijuana plants do not stop developing when there is too much heat. However, their growth will slow down. This is because too much heat affects the process of photosynthesis. The activities of the enzymes are also stunted, and the plants produce very few proteins. However, if it is exposed to heat for long durations, your plant might end up dying.

If you are growing marijuana in a grow room, keep in mind, the maximum temperature for marijuana grow tent success is 85°F. Temperatures higher than this will result in the plant’s death.

(Video) The importance of Temperature when growing Cannabis!

When the marijuana grow room temperature is above 85 degrees Fahrenheit, photosynthesis will be affected; however, the plant will still produce sugar. For the sugars to be distributed throughout the plant, the plant temperature should be above 20ºC or 60ºF. In the case of sugars, heat is a good thing. If the plant is not warm enough, the sugars will be stuck, and the plant will suffer. Once the plant is warm enough, the sugars will be distributed to their respective places.

However, if the temperature is above 85ºF during the flowering stage, bud growth will be stunted, which may result in an airy and loose bud. The potency and smell of your buds may also be reduced. Maintaining the right temperatures during the flowering stage is crucial if your goal is to produce densely packed buds.

Too Hot for Pot? >> The Best Temperature To Grow Marijuana (2)

How to grow marijuana in extremely high temperatures

In some areas, high temperatures cannot be avoided. In that case, you may want to consider using a grow tent. Grow tents help ensure an ideal marijuana grow room temperature. They do this by using an exhaust system to move hot air from the grow tent to the outside. If you are not using an exhaust system, you should, at least, make sure you have enough ventilation. An air conditioner can also remove hot air and cool an indoor growing area. Also, keep in mind that your lights will cause heat. Choosing low heat options will lower the temperature in your growing area.

Whether you use a grow tent or grow your plants indoors with an air conditioner, maintaining the ideal temperature is essential for producing the highest quality harvest.

What is the ideal temperature for growing marijuana?

Maintaining the ideal temperature for your marijuana plants when using a grow tent is not always the easiest thing to do. This is because marijuana plants require different temperatures at different stages of their growth.

During the vegetative stage, marijuana plants thrive in temperatures between 70-85 degrees Fahrenheit (20-30ºC). This is also the maximum temperature for marijuana grow tent use.

During the flowering stage, however, the ideal temperature to grow marijuana plants can be a little colder. The temperature should be kept between 65-80 degrees Fahrenheit (18-26ºC). The second half of the flowering stage is when the temperature should be at its coolest. This helps your marijuana plants produce flowers with rich color, as well as increased trichomes, denser buds, and more potent smell.

When growing outdoors, the ideal temperature is a little cooler. Marijuana outdoor grow temperature is best when it is close to 60ºF.

(Video) Best Grow Room Conditions For Maximum Yield - Light (PAR), Temperature and Air (CO2)

On the other hand, you also don’t want it to get too cold. When using a tent, the marijuana grow tent temperature should always be above 60ºF. Anything below that and the plant growth will be stunted, the plant may freeze, and it will eventually die. Sometimes you might experience a night or two where temperatures may fall below 50ºF, but as long as it is not prolonged, you don’t need to worry. Keep in mind, outdoor cannabis may die if the temperature drops below 40ºF. Some plants can withstand the cold, but their yields will be less than that of a typical plant because of delayed growth.

Just like with too much heat, the main problem with cold temperatures is photosynthesis. If it is too cold, your plant will not undergo photosynthesis, and the leaves will develop a purple color. Marijuana plants grown in cold weather are also more susceptible to mold.

In general, the best temperature to grow marijuana is about 68 degrees Fahrenheit during flowering, and 70-78 degrees Fahrenheit during the vegetative stage.

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Soil temperature and marijuana plants

Soil is a crucial component when growing marijuana, so you should make sure that you have chosen the best soil for cannabis growth. We recommend a Pot for Pot’s Superb Soil. It has the perfect balance of nutrients, perlite, and vermiculite to encourage proper soil pH, temperature, and drainage.

Soil is essential from the very beginning of a marijuana plant’s life. Marijuana seed germination is triggered when soil temperature, light, and moisture work together. For the best environment for your plants, consider investing in a soil thermometer to measure its temperature. The soil temperature should be maintained at 80ºF. This ensures that the roots stay warm. It also helps the stems and leaves withstand bouts of colder air (if you’re in an area that gets cool air). You can also place heat mats on the floor to maintain the soil temperature if your plants are not getting enough heat.

What marijuana strains grow well in hot temperatures?

Cannabis plants are hardy. Most marijuana strain will adapt to different climates and environments; however, some strains are better at it than others. When growing marijuana in a hot region, it’s best to choose strains that originated in similar climates.

Here are some marijuana strains that thrive in hot temperatures:

  • Northern Lights is best cultivated in warm temperatures. It provides up to 22 ounces per plant.
  • Amnesia Haze grows in hot and dry regions, preferably grown indoors with a controlled climate.
  • Fruit Spirit thrives in areas where the temperature is hot. It can produce up to 19 ounces per plant.
  • Tangerine Dream can be grown both indoors and outdoors as long as temperatures can be controlled. It produces high yields of about 18 ounces per plant. It reaches maturity in 9-10 weeks.
  • Grape Ape grows best where there is both heat and sun. Grape ape produces high yields of up to 28 ounces per plant. It is mold and pest resistant.

Too Hot for Pot? >> The Best Temperature To Grow Marijuana (9)

What about humidity?

When growing marijuana in a grow tent, you must monitor both the marijuana grow tent temperature and humidity. The same is true when growing both indoors or outdoors; however, it is more noticeable in grow tents. Humidity is formed in the air the plants breathe out, as it contains water vapor. That’s why in a grow room, the moisture will always be at a higher percentage than temperature. This is because marijuana plants emit 90% of the water and only absorb about 10%.

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High humidity levels are a problem for marijuana plants. Excessive humidity can slow your plant’s growth, encourage the development of mold, or even cause root rot. That doesn’t mean your plants want a desert environment, either. Excessively low levels of humidity can stunt growth and cause stress on the leaves.

Also, just like temperature, marijuana grow tent temperature and humidity needs differ depending on the plant’s growing stage. During the seedling stage, keep the humidity levels at around 65-70%. During the vegetation stage, humidity levels can lower to a range of 40-70%. Finally, once you reach the flowering stage, humidity levels should range between 40-50.

Near the end of your plant’s life, during the late flowering stage, humidity levels should range between 30-40%. Purchase a hygrometer to monitor the humidity levels of your plant’s environment.

Fixing and preventing marijuana heat problems

Indoors

If you are growing indoors using a tent, the marijuana grow tent temperature is a crucial factor in whether your plants merely survive or thrive. To create and maintain the ideal temperature in a grow tent, start by ensuring you have ventilation. Fans are a great way to do this in a grow tent, or you could use air conditioning in a larger grow room. Your focus should be on any heat that is near your plants since excessive heat can cause heat stress. Most of the time, growing lights are the main heat source to be concerned about.

Maintain a cool environment by installing an exhaust fan to make sure that the hot air from the area is directed outside. To prevent smells from escaping with the heat, use an exhaust fan that has a carbon scrubber.

You can also fix a heat problem by situating the lights a little bit further from the plants. You can also use cooler lights. Air or water-cooled grow lights can protect the plants from heat, despite the light intensity. If using regular grow lights, keep them at least three feet away from your plants. Air or water-cooled lights can be placed as close as a foot away from your plants.

Outdoors

When outdoor marijuana plants are affected by heat stress, it can take several weeks to recover, so it is essential to prevent that stress in the first place. Luckily, protecting your outdoor cannabis plants from heat stress is almost the same method as protecting yourself – stay hydrated. Use micro-sprayers to cool your plants. This simple step can cool your plants by up to 30 degrees. You can also keep your roots cool by using fabric pots. This type of material allows your roots to breathe.

When you choose to water your plants can also help with absorption and prevent heat problems. To help keep your plants hydrated, water in the early morning before the sunrise and late in the evening after sunset. When you water at these times, your plants are better able to absorb more of their water because it does not evaporate as quickly.

(Video) THE BEST WAYS TO DEAL WITH HEAT STRESS!

Placing your plants in the shade can also help; however, you should only do this for the occasional heatwave. If your plants are not regularly exposed to direct sunlight, they may go into shock when they eventually are exposed to it. This includes moving your plants that are growing in containers.

You can also use seaweed kelp extract to protect your marijuana plants while they are recovering from heat stress. This ensures the plants are protected from the possibility of contracting heat stress in the future.

Growing marijuana is one of the easiest things to do; however, you’ll get the best results if you focus on creating and maintaining the correct temperature. Start with high-quality seeds or clones, Superb Soil, and a little bit of love, and you’ll be well on your way to growing healthy marijuana plants.

FAQs

Is 82 degrees too hot for Grow Tent? ›

Managing grow tent heat is one of the more difficult, frustrating aspects of indoor growing. Not too hot and not too cold; many of the plants we grow are just like us and prefer similar temperatures - between 65 to 85 degrees Fahrenheit.

What happens if grow room is too hot? ›

High temperatures lead to earlier flowering and small flowers. Too much heat during the flowering stage will also slow down bud growth and reduce the plants' smell and potency. Plants' roots and leaves. Hot temperatures affect transpiration, which in turn, causes stress on the leaves and roots of the plant.

Is 85 too hot for a grow room? ›

A standard, well ventilated grow room should be kept between 75-85 degrees Fahrenheit under optimal conditions. Temperature can be raised or lowered according to your plants' needs.

What temp should my grow room be with LED lights? ›

The ambient room temperature should be below 90 degrees Fahrenheit (ideally 82-85 degrees) and as low as 72 degrees when the lights are on. Temperatures will be lower during the off period when the lights are not in use.

What is the best temperature for flowering stage? ›

Flowering Stage – The best flowering plant temperatures are between 65-80°F(18-27°C).

What temperature is too hot for plants? ›

So, how hot IS too hot for plants? The general answer is around 90 degrees F, with some exceptions to the rule. This means that when temps rise above 90 and remain there for a lengthy spell: Leaves wilt.

Will plants recover from heat stress? ›

Common in nonwoody annuals and perennials, many plants will recover when temperatures drop. The potential for permanent damage increases with the length of time that a plant remains wilted.

What humidity is best in grow room? ›

It's important to lower the humidity levels to 40-50% during this phase. Any humidity level over 60% could potentially damage the plant, which is relying on moisture from the soil to nourish itself.

How close should light be during flowering? ›

During this stage, more light is needed for photosynthesis, so the light source should be located closer to the plants. As the plants progress through the flowering stage, their demand for intense light decreases. The top leaves of the canopy should be between 18-24 inches from the light source to produce flowers.

Where should the temperature be in a grow room? ›

You'll also want to measure the temperature in a variety of spots in your grow room. The best places are in the shadier areas and at the canopy level of the plants but not directly under the lights or right by the fans, as this may give a distorted result.

Do buds grow at night or day? ›

Cannabis plants need short days (or more specifically long nights) in order to start flowering and make buds. Most indoor growers give their plants 12 hours of darkness and 12 hours of light each day to initiate budding and continue with that 12/12 light schedule until it's time to harvest.

Is it OK to water plants on a hot day? ›

Yes, you can water plants on a hot day – the leaves of plants will not get scorches or burn spots if they get wet on a hot, sunny day.

How do you keep potted plants alive in extreme heat? ›

Try putting potted plants inside larger pots to give them some insulation and shade, but make sure both pots have good drainage.
...
How to keep plants alive in this blistering summer heat
  1. Water deep. ...
  2. But don't overwater. ...
  3. No water in the sun. ...
  4. Set up some shade. ...
  5. Don't remove damaged foliage. ...
  6. Stop all pruning until fall.
14 Jul 2018

Do plants need more water when it's hot? ›

The short of it is that your plants need more water in extreme heat, but it's not just the amount of water that matters. Plants also need water to be applied in the most beneficial way. Plants are amazing organisms.

Does heat affect bud? ›

The ideal grow temperatures for cannabis plants in a grow room is between 50-60 ˚F during dark periods and 70-7 ˚F during light periods. Heat stress can cause these negative effects on your weed grow: Wilting and destruction of your weed plants.

How do you tell if a plant is stressed? ›

A common sign your plant is stressed is if it's dropping leaves and flowers. Stressors can include lack of water, over watering, temperature change, less light – you name it. If the problem isn't too little or too much water, or something else easy to identify, have patience.

Can Helicopters see grow tents? ›

Police helicopters are able to see illegal growing operations via their camera when plants are being grown out in the open, they are in a room with windows that can be seen through, or when the area they are being grown in is radiated much more heat than its surroundings.

How many fans do you need for a grow tent? ›

Fan Requirement Table For Common Grow Tent Sizes
Tent Size (Width X Length X Height)Add 5 Feet DuctRecommended Fan Size
4x4x6.51826'' Fan
5x5x6.5284.46'' Fan
4x8x6.54682*4'' Fan
5x10x6.5731.32*6'' Fan
7 more rows
29 Jun 2022

Do you leave fan on all the time in grow tent? ›

We recommend you run your inline fan all the time during the day, and to turn it off an hour dark after you turn off the lights. This will allow your plants to bloom undisturbed.

Is 81 too hot for Grow Tent? ›

Common grow room temperatures include (but are not limited to): Clones/Seedlings: 72-82°F. Vegging Stage: 68-78°F.

Is 80 degrees too hot for plants? ›

So, how hot IS too hot for plants? The general answer is around 90 degrees F, with some exceptions to the rule.

Is 80 Degrees to hot for seedlings? ›

Many factors affect seed germination, but the most challenging for gardeners and often least understood is soil temperature. While there is can be variation from one seed type to the next, most seeds for warm-season edibles prefer soil temperature between 70 and 80 degrees Fahrenheit (21.1 and 26.7 Celsius).

Is 80 Degrees to hot for Autoflowers? ›

Autoflower temp and humidity requirements are practically the same as for cannabis plants in general. Autoflowers thrive with day temperatures around 23–28°C (73–82°F) and a drop of no more than 5–10 degrees at night. The humidity should be ideally between 40 and 60%.

Is it OK to water plants on a hot day? ›

Yes, you can water plants on a hot day – the leaves of plants will not get scorches or burn spots if they get wet on a hot, sunny day.

How do you reduce heat stress in plants? ›

To lower the temperature, a layer of four-to-six inches of straw, pine needles, leaves or grass clippings will help. Also watch for vegetables dropping blossoms in times of high heat. Plants, such as tomatoes, peppers, squash, melons, cucumbers, beans and even pumpkins, are notorious victims.

Is it OK to water plants in the middle of a hot day? ›

Watering in the heat of the day shouldn't hurt the plants -- it actually cools them off -- but it's a far less efficient use of water as much of it will evaporate before reaching the roots. Avoid getting plants wet late in the day unless it's the only possible time you can water them.

How hot is too hot for Grow Tent? ›

If you are growing marijuana in a grow room, keep in mind, the maximum temperature for marijuana grow tent success is 85°F. Temperatures higher than this will result in the plant's death.

How hot is too hot for Autoflower? ›

If the temperature gets too high you should upgrade your ventilation and never let the temperature surpass 35°C (95°F) or else your plant will suffer and die quickly. If the temperature is too high then the plant can't absorb CO2 properly and it slows down the growth a lot.

Why is my grow room so hot? ›

If the air outside your grow room is hotter than the air in it, first make sure you're drawing air in from the coolest place inside your property. If nowhere is cool enough, you might need to switch intake fans off. Otherwise you'll just be heating your grow room further.

Is 60 humidity too high for flowering? ›

Any humidity level over 60% could potentially damage the plant, which is relying on moisture from the soil to nourish itself. One to two weeks before harvesting the cannabis, aim for humidity levels below 40%. This can ultimately help improve the yield, flavor and appearance of the plant.

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