Humidity plays a necessary role in affecting the degree of evaporation from cannabis plants. When humidity is low, your plant absorbs more nutrients and water. If for some reason the humidty becomes too high or low, the cannabis plant protects itself. Therefore, it naturally slows down the growth of your plant due to the lack of water absorption. Thus, you must have sufficient moisture in your cannabis plant. So how do we know whether cannabis like moisture?
Cannabis likes moisture as it grows. In contrast, it does not like moisture during the flowering stage. During the growth phase of the plant, unlike the flowering phase, it needs a high level of humidity. The main reason for this is that the roots of baby plants are much smaller. Measure the humidity with a hygrometer. In the early stages of plant growth, the humidity can be around 70% and you can reduce it to 40% by 5% each week.
Before we continue, we need to discuss the relationship between temperature and humidity. First, you need to understand that the percentage of water that can be absorbed is determined by the temperature. At 68 degrees Fahrenheit, the air can hold up to 7.2 ml of water. In this case, the corresponding humidity of the air is 100%. At such temperatures and humidity, you are guaranteed not to see anything as the water vapor is very high.
At 32 degrees Fahrenheit, the air absorbs about 5 ml of water. For this reason, the weather is much drier in winter than in summer. Since you ventilate your growing room quite often, moisture will also be thrown out. Therefore, you should make sure your cannabis plant is moist at all times to keep the humidity high.
Cannabis and Humidity: A Scientific Look
Humidity is a big problem for cannabis growers. But why is humidity so important for cannabis plants and what is the ideal humidity in your growing room? To better understand why moisture is important to plants, it helps to think about how plants absorb ambient air. Remember that all plants breathe carbon dioxide from their leaves from the environment. In doing so, of course, they lose some of the water held in their leaves. Dry air causes the plants to lose more water from the moist air as they breathe, reducing the overall moisture content of the plant faster. When the environment becomes too dry, the plants lose more water than their roots can recover.
In this case, the plants almost completely close the pores in their leaves and minimize moisture loss. Of course, this works, but it also means that the plants get less carbon dioxide from the environment. This causes the plant cells to die, making them drooping and looking diseased. You may now want to water your plants more regularly to combat moisture loss in dry weather. Although it looks logical, it won’t work. Watering the soil too much will only reduce the amount of air in the soil, further drowning the plant and making the plants more prone to root rot. However, plants thrive when they have the right amount of moisture. The right amount allows plants to open their pores more fully, breathe more carbon dioxide, and grow faster.
However, very humid conditions can also be detrimental to plants, particularly hemp, and put them at risk for bud rot and other diseases as the water collects in the thick leaves and creates the environment for diseases. This is ideal for bacteria and fungi. When we talk about perfect humidity for a plant, it’s important to understand what “relative humidity” is. This is a complicated term, so we’ll try to explain it in the simplest way possible. However, it is important to note that the amount of water the air can hold depends on the temperature. Of course, hot air can hold more moisture than cold air.
The relative humidity is a term that refers to the amount of water that the air can hold at a given temperature. As soon as the relative humidity exceeds 100%, the air can no longer hold the excess water and condenses into water droplets such as fog, morning dew, or rain. For example, suppose the temperature in your growing room is 30 ° C (86 ° F) and the relative humidity (RH) is 33%. If you quickly cool the environment to 10 ° C, the relative humidity will rise to 100% (also known as dew point). If the temperature drops further, the water in the air will begin to condense.
The Ideal Humidity Levels for Cannabis
The ideal relative humidity for plants varies. Plants native to hot and tropical regions are well adapted to these temperatures and will grow better at higher relative humidity than plants in colder and more temperate climates. History shows that cannabis comes from different parts of the world. Indica species emerge and grow better in drier mountain regions, and can also withstand lower temperatures. Sativa strains grow naturally in hot, subtropical climates and prefer warmer, more humid conditions. Because cannabis strains are largely crossed, most strains purchased from seed banks are a type of Indica-Sativa hybrid. Therefore, it is not enough to “guess” what the ideal moisture level might be for a particular species based on its genetics.
Instead, most growers will evaluate their plants and their morphology and try their relative humidity levels to find the perfect place for each harvest. However, there are some basic “rules of thumb” you can follow: seedlings and clones need 65-80% RH. Remember, these fragile young plants have weak root systems. By increasing moisture, it can absorb more water from the environment and focus on developing strong roots. At this early stage, keep temperature levels at 25 ° C during the day and 21 ° C at night (77 ° F and 70 ° F). Herbal plants, on the other hand, tend to prefer moderate humidity. There is no exact number here, but you should stick to a value between 55-70% depending on the load.
Temperatures should be between 22 and 28 ° C during the day and between 18 and 24 ° C at night. Herbal plants have a strong root system and absorb more water from the soil, so most growers reduce moisture slightly at this stage. At the beginning of flowering, most growers agree that the plants benefit from less moisture. Again, there is no ideal number to hit, but most fall between 40% and 50% and sometimes up to 55%. You should also lower the temperatures to 20-26 degrees Celsius. At the end of flowering, try to reduce the humidity by 30-40% and keep the temperature between 18 and 24 ° C during the day, followed by slightly cooler nights (16-24 ° C).
Note that the numbers shown here are guidelines. Growers have a lot to say about great results when humidity is high, especially during the flowering phase. The best way to avoid this is to use a quality thermometer and hygrometer (or an all-in-one thermo-hygrometer) to regularly check your plants and monitor the temperature/humidity in your growing room. . If you want to reduce the humidity in your growing room, try the following:
- Run your exhaust duct at higher speeds to extract more hot air from the room (remember, warm air contains more water).
- Increase the cold air supply.
- Water your plants at the beginning of the lighting stages.
- Use a dehumidifier.
On the other hand, if you want to increase the humidity in your growing area, try the following:
- Lower the exhaust fan to keep more warm air in your growing room.
- Increase the temperature in your growing room.
- Spray your plants (don’t do this to flowering plants to prevent bud rot).
Adjusting the Humidity Levels for Cannabis Plant
Your cannabis cuttings have very small roots at first, so they cannot absorb much water yet. At this point, you want a very small amount of water to evaporate. The cutting process evaporates a small amount of water when the humidity is high and you need fewer roots. Another way to reduce evaporation is to cut the largest leaves in the middle of the cut. 70% moisture is exactly what you want when you put the cuttings in your cannabis plant.
I recommend placing the cuts under a 600-watt HPS lamp in an environment with 30% humidity for good results. When the second or third week of flowering begins, the roots reach the size of the actual plant. Roots must be durable so that water and nutrients can be well absorbed. Seedlings need a separate rule because they have a parent root that absorbs moisture and grows fairly quickly when they sprout. Never cut the leaves of a plant. Leaves are necessary to absorb light and evaporate water. Keep humidity high so seedlings can absorb water and food from leaves. Start with 60% and slowly work down to 40%.
As your plant begins to bloom, you can reduce the humidity gradually. At this point, the roots are very mature and allow the plant to absorb most of the nutrients and water. Since mold is more likely to develop in high humidity environments, you should reduce humidity during the blooming phase. As you age, your cannabis plant is more likely to become moldy. Because of the high humidity, water collects around the spikes, and this is when mold can grow. The most common type of mold is bud rot.
That’s why you have several options for increasing the humidity in your growing room. As a start, you can try spraying the walls and flowers with water. Also, try turning on the light so that the temperature near the plants drops slightly. This way, you don’t need to open the extractor as often. If you put bottles or buckets of water around the growing room, even wet towels, the humidity will increase. The best way to achieve your goal is to use a moisturizer. Humidifiers turn water into water vapor and pour a constant high humidity mist into your room. Depending on which one you buy, it can come with a humidity controller (wiki) to monitor the humidity level and it will open even if it falls below the value you set.
Measuring and Dehumidifying When Necessary
When the cannabis plant begins to bloom, it is necessary to reduce the humidity, so it is necessary to remove the moisture. Try using the exhaust fan at a higher setting than normal, otherwise, it may blow cool air into the room. Dehumidifiers are definitely the best option. It has the ability to dehumidify and ventilate or keep it in a tank. Make sure you have a bigger moisturizer as the little ones fill up quickly. Remember that moisture outside can affect the humidity of your marijuana plant. For example, if the humidity rises rapidly on a rainy day, you can turn off the exhaust fan or set it to a much lower setting. Make sure the temperature does not rise too quickly as the weather outside will be less cold.
Hygrometers are used to measure humidity. All you have to do is place it over the plants, assuming it is in a slightly ventilated area. More expensive hygrometers are generally of higher quality. For convenience, take the one with thread. This makes it easy to see humidity without having to turn on the lights in the room. These devices have a built-in memory bank that keeps track of the highest and lowest values to see how well you’re staying in the preferred range.
Watering your plants will slightly increase the humidity, which is a good thing while growing because all you have to do is spray the floors and walls to increase the humidity. During the flowering phase, humidity usually increases significantly after the plants have been watered. As soon as the grow room light turns off, the temperature drops and there is not much hot air left to draw in, which is often the cause of the increased humidity. Give your plant some water after turning on the lights. In this way, they evaporate most of the water during the day. Note that it is not necessary to spray water on the buds, as increased moisture will increase the likelihood of mold growth.
Humidity is not a concern if you grow your cannabis outdoors. Spring and early summer create higher moisture levels, which works great as there are no buds for moisture build-up in the plant. All moisture from the morning dew on the plant easily evaporates during the day. After the summer ends, the flowering phase begins, and the weather changes, resulting in cooler days and more rainfall. This usually increases the humidity. In the colder months, morning dew can be a problem as the sun is not guaranteed to rise and temperatures are sometimes too low to evaporate.
Thankfully, a little rain won’t rot the buds, but you might still want to check just in case. During the last flowering stage, it may be a good idea to remove dew on your cannabis plants in the morning. If you find that rain is predicted, move your plants to a place where they will be kept dry and protected from the rain.
Managing Humidity: A Must for Cannabis Growers
If you want to grow strong and sticky buds, your hemp will require special attention due to its many needs. One of the often-overlooked needs of cannabis plants is moisture. Believe it or not, moisture is very important to your plant! Humidity determines the amount of beverage your plants should drink, as well as your plants’ resistance to mold/fungus. If done right, you can improve plant growth and increase your yield. Fortunately, there is not much to learn, so you can become the master of moisture in your growth with very little effort. Today we provide you with the information you need to precisely control humidity and thus increase the production of your plants.
At all stages of cannabis growth, your plants need constant water intake, and the amount of water they need will depend on the humidity in your growing room. When humidity is low, they absorb more water from their roots. Because moisture changes the amount of water your plants drink and the water you feed your plants contains nutrients, controlling humidity gives you better control over the nutrient supply to your plant.
However, humidity control isn’t just about prevention. Sufficient moisture supports strong, healthy foliage plants that grow vigorously. In fact, growing with DWC (Deep Water Culture) / Bubbleponics while vegetables with sufficient moisture can become a struggle to control uncontrolled plant growth. As soon as your plants produce buds during the flowering stage, you can also change the humidity in your growing area just before harvest so that your plants produce more resin (THC-containing trichomes/straw) while preventing mold from infecting plants. High humidity can sometimes cause mold or bud rot, making it a grower’s worst nightmare for dense, oily mother buds.
We don’t want to scare you, but you need to know what will happen to a growing room where moisture management is poor. We know the importance of moisture because we experienced each of these issues firsthand! White powdery mildew is a fungal disease that occurs in high humidity environments. This can be difficult as young cannabis plants will thrive in humid environments. Fortunately, you can avoid WPMs by ensuring proper air circulation in your growing area. A small oscillating fan works wonders even at low temperatures.
In my opinion, bud rot or mold is one of the worst pain a grower can suffer from poor moisture management. Imagine collecting a huge, dense main tail from your plant and find that the interior is all white or brown with mold. Buds in this situation cannot be used and should be 100% discarded. Humidity is a factor that partially determines how much your plants drink. When the air dries, your plants tend to drink more from their roots. If they are already drinking more due to high temperatures, low humidity can cause them to drink too much water from their roots and take in too many nutrients.
When your plant gets more nutrients than the plant can use, the leaves show yellow or burnt tips due to the burning of the nutrients. Sometimes too low humidity can cause other major nutritional problems. Cannabis plants like higher humidity when young and lower when they mature. To be honest, if you don’t have these conditions, you may not be growing as fast or healthy as they are.
How to Manipulate the Humidity Amount
Okay, now you know why you need to manage humidity when cultivating cannabis, but you may not be sure which moisture to aim for. Humidity is actually a measure of the amount of water vapor “trapped” in the air. There are several ways to measure humidity, including “absolute”, “specific” or “relative” humidity. Most growers talk about relative humidity or relative humidity when talking about humidity in the growing room. Relative humidity measures the amount of water in the air according to the maximum amount of water the air can hold at this temperature.
Clones need time to develop a water-absorbing root system. Maintaining high moisture levels greatly increases the chances of successful rooting of clones and increases the growth of young clones. For this reason, many breeders use a moisture dome for new clones. Cannabis seedlings and young plants in the vegetative stage develop a large amount of leaf mass in a perfect growing environment, and plants can sometimes grow foliage faster than roots. However, roots are not the only way your plant gets water. Leaves can draw water vapor directly from the air and higher humidity allows the leaves to bring more water to the plant when needed. Until your plant has fully developed roots, low humidity can slow growth. The idea is to create a pleasant and warm environment that mimics spring or summer.
Ideally, the relative humidity in your growing room should be reduced to around 40-50% at the start of flowering. Just before harvesting, some growers lower the humidity to below 40% or even less in order to force the cannabis buds to produce more resin, but I’ve seen this force some plants to this technique, so Beware. Be sure to lower the humidity a bit to see how the plants react before exposing the plants to the extreme environment. At the beginning of the flowering phase, your cannabis plants will have formed a large root system to meet their water needs. They can still absorb water from their leaves, but keeping humidity relatively low during the vegetative stage will prevent mold growth. Mold is especially dangerous during flowering as it can form on your buds or buds without you realizing it. If you notice mold on any of your buds or if the buds are rotting from the inside, you should discard the contaminated buds immediately.
Bud rot can devastate the entire crop. So if a bud becomes infected, do thorough research in your growing room to find out more. If you can’t reduce moisture and you already have a creeping mold problem, it may be best to reduce losses and harvest immediately to prevent further bud rot. Even when humidity is low, it is important to maintain air circulation over and around your plants. Small fans that blow above and below the vegetation keep the air moving so no wet spots appear anywhere on the plant.
Keeping the humidity around 50% will allow your buds to dry out, but they won’t dry out too quickly. This area is also great for preventing mildew, so if you’re a beginner it won’t get better with drying. As an advanced drying and curing technique, some growers want to keep the humidity slightly higher to allow the buds to dry more slowly (this can improve the quality of the dried buds). Drying with high humidity is considered an advanced technique, as special care must be taken during drying to prevent mold growth on harvested buds. It is good to circulate air in the drying area, but it is recommended not to blow air directly on the buds to avoid too fast drying.
Humidity and Temperature Relationship for Cannabis
Temperature and relative humidity are closely related. Relative humidity measures the amount of water held in the air in relation to the maximum amount of water that can be stored at this temperature. Plants tend to thrive at different relative humidity depending on the air temperature. When the air becomes saturated with water, it tends to form water or dew layers on the leaves that cause mold. For those who want to learn more about the science behind this, there is a term used by greenhouse growers known as VPD or Vapor Pressure Gap, which roughly measures temperature and relative humidity.
It is important to know that humidity and temperature are closely related. At the point when we discuss dampness, we normally mean relative moistness (RH), which is the proportion of water vapor’s partial pressure to the max vapor pressure of the same water at a similar temperature. When you know the basic principle that warm air contains more water vapor than cold air, you get the full picture. This is one of the reasons why a large amount of hot air should be removed from our growing room and ideally cool air should be taken in; hot air contains a lot of water vapor. So, basically by managing the water vapor content in the room, you can decide on the amount of moisture as well.
We have to characterize what moistness and temperature control really mean when raising cannabis. It makes sense to divide the life of cannabis plants into four different stages, where humidity and temperature must be adjusted to ensure healthy growth. Don’t think humidity and temperature controls are complicated and not worth it! This is usually very simple and all about keeping the settings within a certain range and as stable as possible. The first thing you should do is buy a hygrometer and a thermometer, preferably a digital one with a memory function that also displays the maximum and minimum values of the past. Some hygrometers are not the most accurate. So don’t worry about having more than one device to compare values in your growth room. Now that we can closely monitor our conditions, we can access the essence of humidity and temperature control: the true humidity levels and temperatures we seek.
Hemp likes a comfortable or slightly warmer room temperature that is neither too dry nor too humid. For most breeders, that’s all they have to worry about. If your growing room is hot or cold, damp or dry, this is a sign that you may want to look for a change in temperature and/or humidity in your growing area. In general, cannabis plants prefer temperatures between 21 and 27 ° C during the day when the lights are on. When the lights go out (or at night), cannabis plants are happy with slightly lower temperatures.
Colder temperatures tend to inhibit growth. Temperatures below 15 ° C (60 ° F) can disrupt plant growth, and freezing temperatures can affect or even kill a cannabis plant. Just as cold temperatures are not good for cannabis production, hot temperatures have their own harms. Note that very high temperatures during flowering will not only slow bud growth and produce softer buds, but will also reduce the effectiveness of your buds by burning some terpenes and cannabinoids. It is important to control the increase in ambient temperature during the flowering period!
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