When it comes to growing cannabis, two of the most important factors to keep in mind are temperature and humidity. Temperature and humidity both play very important roles in terms of cannabis growth. This is true on many different fronts. Moisture absorption, the health of the roots, the health of the main plants, diseases and pests, and much more, are all affected by both temperature and humidity levels.
As you could probably guess, if your humidity and temperature levels are not ideal for your grow space, then you’re going to run into some really serious issues. This is what today’s article is all about, talking about the impact of both humidity and temperature on cannabis growth.
We’ll cover a number of extremely important factors, such as what the best temperature and humidity levels are for growing weed indoors according to various growth stages, what to do if your growth stage is either too wet or too dry, as well as too hot or too cold. We’ll also take a look at some valuable tips on how to maintain the ideal temperature and humidity levels in your grow space.
The Best Temperature for Growing Weed Indoors
First, let’s take a look at what the best temperature for growing weed indoors is, according to each growth state. As you’ll see below, exactly how warm the temperature should be during each growth stage varies slightly.
Germination
Turn the germination stage, temperatures should be fairly warm, anywhere between 70 degrees and 85 degrees Fahrenheit.
Seedling
During the seedling stage, the environment should be slightly cooler than during both the vegetative and the flowering stages, as seedlings are quite delicate. A temperature range between 70 degrees and 80 degrees Fahrenheit is ideal.
Vegetative Stage
Cannabis plants during their vegetative stage are growing branches and leaves, and they like it slightly warmer. A temperature range between 70 degrees and 85 degrees Fahrenheit is ideal.
Flowering Stage
As a cannabis plant enters the flowering stage, you want to turn the temperature down slightly, to within a range between 68 degrees and 78 degrees Fahrenheit.
Once the mid flowering stage hits, he wants to turn the temperature down even a little more, maintaining a level between 68 degrees and 75 degrees Fahrenheit.
Once the late flowering stage occurs, you can lower temperatures even more, which helps to increase resin and therapy and production. During the late flowering stage, maintain a temperature between 65 degrees and 75 degrees Fahrenheit.
Pre-Harvest
During the few weeks before harvest, you want to turn the temperature down even more, keeping it within a range of 60 degrees to 72 degrees Fahrenheit.
The Ideal Humidity Level for Cannabis Plants
Now that we know what the ideal temperature for cannabis plants is, let’s take a look at the ideal humidity level according to each growth stage.
Germination
Humidity levels during the germination stage should be very high to allow a successful sprouting to occur. The humidity should be between 70% and 90%.
Seedling
Cannabis seedlings prefer relatively high humidity levels to promote leaf development and to prevent moisture stress from occurring. A humidity range between 70% and 80% is ideal here.
Vegetative Stage
When the cannabis plants enter the vegetative stage, they do well in a fairly wide humidity range, anywhere between 40% and 70%. Remember that high humidity levels are ideal for growth, but lower levels help keep away mold and pests, so somewhere around 55% should be ideal.
Flowering Stage
To stop mold and mildew from growing, when cannabis plants enter the flowery stage, you should reduce the humidity levels to anywhere between 40% and 60%, with around 50% being the ideal.
As the flowering stage progresses, especially towards the late flowering stage, you want to decrease the humidity levels once again, to anywhere between 30% and 45%, with around 35% being ideal.
Pre-Harvest
During the final weeks of flowering, right before harvest, you don’t want the humidity levels to be anywhere above 35%, or 40% at the very most.
What if Your Grow Space is Too Dry?
As you could probably tell by this time, if cannabis plants are too dry, there will be some very negative effects, so let’s take a look at what these might be.
- If cannabis plants do not receive enough moisture, they can start to wilt, as leaves start losing their firmness. This is a big indication of water stress and will quickly lead to damage or death.
- If weed plants don’t get enough moisture, it will also result in reduced nutrient uptake. If plants don’t have enough water and humidity, then they can’t properly absorb nutrients from the soil.
- If plants can’t properly absorb nutrients from the soil and don’t have enough moisture, it will also result in insufficient and stunted growth. Cannabis plants won’t grow very well if they don’t have enough humidity.
- Overall, if your cannabis plants are kept in conditions that are too dry, it will result in reduced bud development and lower yields overall.
- Not only will the yields be lower, but if the plants are kept in conditions that are too dry, the potency, flavor, and overall quality of the buds will also not be very good.
- Plants that are stressed out also become more susceptible to pests and diseases.
What if Cannabis Plants Are Too Wet?
Just like if the humidity levels for cannabis plants are too low, humidity levels that are too high can be very detrimental as well. You don’t want your growth space being too wet. The following are all signs or results that your cannabis plants are in conditions that are too wet.
- If the humidity levels in the grow room are too high, it will lead to reduced growth and inhibited root development. If the roots are too wet, they’ll no longer be able to uptake nutrients that the plant needs to grow.
- One of the biggest threats to your cannabis plant is if it is kept in the humidity levels that are too high, as the plant will start developing root rot. If the roots are too wet for too long, they will quite literally start to rot, which will quickly result in the death of your cannabis plant.
- Another big problem that occurs if your cannabis plant is being grown in conditions that are too moist is that pests are easily attracted, especially gnats and aphids. They love damp soil. Furthermore, high humidity levels are also fantastic for encouraging the growth of mold and mildew.
- Even if your plants don’t outright die due to excessive moisture levels, the result will still be less than ideal. The flavor, potency, yield, size of the buds, and everything in between will all be affected. The bottom line here is that ideal humidity levels are very important.
What if Your Grow Space is Too Hot?
Now that you know what happens if cannabis plants are too dry or too wet, let’s take a look at what might happen if your grow space for your weed plants is too hot.
- First and for most, cannabis plants kept in very high temperatures can lead to what is known as heat stress, with symptoms such as drooping, wilting, and leaf curling.
- Cannabis plants that are far too hot will also not be able to properly engage in photosynthesis, which means that they won’t grow as quickly or as tall.
- If you’re weed plant is kept in conditions that are far too hot, it will also affect its ability to absorb nutrients from the medium. This may at times lead to nutrient deficiencies.
- If your cannabis plant is too hot, it will cause moisture to evaporate too quickly, which will often lead to growers providing them with too much water, which can then lead to over watering issues.
- All of the issues discussed above so far lead to the cannabis plant not being able to grow big buds, to grow very many buds, or to grow potent buds. The quality, size, potency, and aroma of the buds will all be affected by temperatures that are far too hot.
What If Your Grow Space Is Too Cold?
Just like if the grow space is too hot, there are also some pretty big negative consequences if your grow space for your cannabis plant is too cold.
- The colder the conditions are, the less efficient photosynthesis becomes, which results in the stunted growth of cannabis plants. They just won’t grow as big or quickly.
- If temperatures are too cold, the ability to absorb nutrients from the soil can also be impaired, plus the metabolic activity is just much lower overall. A cannabis plant that is cold cannot easily convert fuel into energy.
- There are certain pests and diseases that are more prevalent when temperatures are too low.
- Overall, if the temperatures for cannabis plants are not ideal, it will result in a decreased terpene profile, less cannabinoids, and lower yields overall.
How to Maintain Optimal Temperature and Humidity Levels in a Grow Room
Now that we know how temperature and humidity affect cannabis growth, let’s talk about some of the best ways to maintain the ideal levels of both within your growth space.
Monitoring is Essential
To maintain the ideal level of temperature and humidity for your marijuana plants when growing cannabis indoors, using monitoring tools is essential.
This means that you need to have a thermometer and hygrometer to keep track. A thermometer measures temperature, whereas A hydrometer measures humidity levels. Getting an accurate model is essential for indoor growing.
Use Heaters and Coolers
To grow cannabis indoors and to maintain the proper temperature levels, using heaters and coolers is recommended. Of course, whether you need a heater, such as a small space heater, or something that will cool the space down, such as a small air conditioning, depends on your specific situation.
When you have a good thermometer that lets you know exactly what the temperature is like, you can then make the adjustments as needed. Using electronic heaters or air conditioning units is perhaps the easiest way to maintain ideal temperature levels.
Use Humidifiers and Dehumidifiers
When you grow weed indoors, just like using heaters and coolers is ideal for maintaining temperature levels, using humidifiers or dehumidifiers can be very beneficial for maintaining ideal humidity levels.
It is certainly the easiest way to do so. Once again, which of these two tools you will need will depend on your current humidity level and what the needs of your cannabis plants are.
Maintain a Good Watering Schedule
As far as humidity levels are concerned, remember that moisture from the soil or growing medium will evaporate into the air and contribute to humidity levels. On that note, remember that if temperatures are too hot, it will also cause too much water to evaporate out of your growing medium, and cause higher humidity levels.
Therefore, maintaining a good watering schedule is essential. A rule of thumb here is that if you can stick your finger down into the soil down to the second knuckle and it is bone dry, and it is time to water your plants. However, if the soil is still moist down to your second knuckle, then you can wait a little longer to water your plants.
Insulate Your Grow Space
Having temperatures that are too high or too low is one problem, but temperature fluctuations are another. To avoid temperature fluctuations, having an insulated growth space is essential.
Good insulation will allow you to easily maintain temperature levels in combination with your heating and cooling equipment. Furthermore, if too much heat or cool air can escape, you’ll also end up using much energy and end up racking up a big power bill.
Get the Right Kind of Lights
Of course, having the right kind of grow lights is essential for both the vegetative and flowering stages in your indoor grow room. That being said, there are many different kinds of lights out there designed to grow marijuana indoors, but not all of them are ideal. There are certain kinds of life that release way too much heat, which is not ideal for cannabis cultivation.
This will end up increasing both the humidity and the temperature in your grow space, which as you know by now, can have some serious consequences. Your best course of action here is to get a very high-quality LED grow light that has heat dissipation features. LED grow lights generally don’t get that hot to begin with, and with some good heat dissipation features, growing marijuana indoors should be a piece of cake.
Ventilation is Crucial
The other important aspect here is ventilation. If you have good ventilation, allowing excess heat and moisture to dissipate is easy. However, if you have a sealed grow space that has no ventilation, heat and moisture will just continuously build up.
Conclusion
As you can see, both temperature and humidity levels play a very important role in healthy cannabis growth. If either of those two are either too high or too low, you’re going to run into some serious problems.
