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.
What's 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.
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 and/or buds with high THC.
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.
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.
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%.
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
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.
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.
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 and most weed 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.