Humidity is one of the most overlooked aspects of cannabis cultivation, but it can have a huge impact on your grow and its health. It determines how much water your plants will drink, and the amount of nutrients they will absorb.
This makes humidity control one of the most important factors in a successful and productive grow. The good news is, it’s pretty easy to master!
Humidity
When it comes to the indoor growing process, air humidity is a critical consideration for optimal production. A properly designed grow room or greenhouse enables you to maintain ideal conditions, ensuring your cannabis plants receive the moisture they need throughout their entire life cycle.
The relative humidity of the air in your grow space (RH) is a measurement of how much water vapor is present in the air. It’s expressed as a percentage from 0% to 100%.
Humidity levels also depend on the stage of the cannabis plant’s growth, with different strains requiring differing amounts of moisture. It’s important to adjust humidity levels to match the needs of each stage, as this will help your cannabis produce the best results.
During the seedling and cuttings stages, high humidity levels will allow the plants to absorb more moisture from the soil, which helps them develop a strong root system. However, if these plants remain at high humidity levels they will become susceptible to mould and mildew.
It’s vital to lower these seedling and cutting RH levels as soon as possible. This will ensure they don’t become overly stressed and can take advantage of the nutrients and minerals in the soil.
As the plant grows, it will begin to transpire more rapidly, releasing water into the air. The rate of transpiration will vary depending on the level of humidity, so it’s important to regulate this as the plant matures.
Another factor that influences the level of transpiration is the temperature. Low temperatures will affect the speed at which water vapor can escape from the leaves, reducing the amount of moisture they can hold.
Furthermore, the temperature of the air will influence the ability of your plants to uptake nutrients as they grow. If the air is too cold, the roots will be unable to absorb nutrients from the soil, which could lead to nutrient lockout and stunted growth.
It’s easy to underestimate the importance of humidity, but it’s one of the most crucial factors in determining your cannabis yield and quality. It’s a simple and effective way to enhance your overall output and reduce the risk of pests, diseases, and poor quality weed.
Temperature
Air temperature is a major factor in cannabis cultivation, so you need to know how to control it. While it may not seem like a big deal to some growers, proper air temperature is one of the most important factors in a cannabis plant’s health and yield.
High temperatures can kill a cannabis plant. They can also cause the plant to grow more slowly.
During the vegetative stage, your plants should be kept between 62degF and 72degF with lights off and between 68degF and 80degF during light-on times. These lower temps reduce the amount of water that a cannabis plant loses through its leaves, which helps to speed up the growth rate.
The flowering stage is another important time to watch the air temperature, as it can be critical for bud formation. At this stage, you’ll want to lower your temperatures by about 5-8degC during lights on and increase them by about 5degC when it’s time to switch to dark-phase.
Humidity is an important factor during the flowering phase as well. During this period, you’ll want to maintain ideal humidity levels at about 40% during the daytime and 60% at nighttime.
As the buds are developing, the cannabis plant will start to absorb more moisture from the atmosphere through a process called transpiration. Transpiration is a natural part of the plant’s cycle and plays a large role in transporting water, nutrients and other vital elements to the flowering cells.
When the air is too humid, your plants’ stomata will close more often in order to restrict the loss of water. This can result in stunted growth and poor quality buds.
Low humidity can also lead to nutrient burn, or “nute burn,” a browning of the tips and edges of your plant’s leaves. This is caused by a lack of oxygen in your grow room and can be prevented by running an extractor fan throughout the growing process to pull warm, stale air out of the space.
It’s important to remember that cannabis plants are more susceptible to issues such as spider mites, powdery mildew and root rot if they are too dry. Too much heat can reduce the potency of a marijuana plant, as well as the scent and taste.
Lighting
As a cannabis grower, lighting is a crucial part of your grow system. It can make or break your yields. It also helps you optimize plant growth and health, maximizing the amount of cannabinoids and other nutrients in your harvests.
Proper lighting for cannabis is more than simply exposing plants to bright light; it’s about adjusting the spectrum, intensity and duration of light at different phases of cannabis growth cycles, as well as providing supplemental, dark light when necessary. This is especially important for marijuana in certain climates and geographical locations where the sun shines fewer or less hours a day than normal.
There are four basic lighting basics that you should be familiar with in order to maximize your yields:
1. Keeping lights at the correct distance is critical during seedling stage.
In a grow room, you should position your lights at least eight feet away from the center of each growing area.
This is a crucial distance because it allows your cannabis to absorb the full range of wavelengths required for healthy development and photosynthesis. Having your light too close can result in a “leggy” or stretched stem, which can be detrimental to your plants’ overall growth and health.
2. Avoid overwatering:
Many rookie growers tend to give their plants too much water, which can cause the soil to become saturated. This can lead to excessive evaporation, increasing the cannabis air humidity levels above ideal values.
3. Use LED grow lights:
In order to achieve the optimal light quality, it’s best to use a high-quality LED grow lamp. These lights are optimized for growing cannabis and provide a powerful light spectrum that stimulates flowering while reducing wasteful wavelengths and energy costs.
4. Use the right bulbs:
The most effective bulbs for growing cannabis are MH (metal halide) and HPS (high-pressure sodium). This type of lighting will help you maximize nutrient absorption and produce the strongest, most productive buds possible. Using these types of bulbs will also reduce your utility expenses and growroom heating needs.
Water
Keeping the humidity in your grow room right is an essential part of generating healthy crops. The cannabis plant is a thirsty plant and requires the proper amount of water vapor in its environment to develop and grow properly.
Depending on the stage of your cannabis plant’s growth, humidity needs will vary greatly. Getting the humidity levels just right during each stage will make your plants produce dense, potent buds with compact calyxes filled with aromatic and tasty trichomes.
The most important factor to keep in mind when it comes to controlling your grow’s humidity is that it affects how much water your marijuana plants drink, which will have a direct impact on how well they absorb nutrients. If the air becomes too dry, your plants will start to drink more than they can regain through their roots, which may result in a “nutrient burn” – leaves that turn yellow or brown and have a rough texture.
Humidity levels also affect how resistant your cannabis plants are to mold and mildew. If your grow room is too humid, this can lead to the formation of molds and mildew that can destroy your crop.
Another key factor to control is temperature. The optimal temperature for cannabis cultivation is between 75°F and 80°F. This allows your plants to maximize their growth potential and avoid nutrient lockout or deficiencies.
Maintaining a good air flow and proper ventilation in your grow room will also help keep the humidity level within an acceptable range, reducing the risk of mold and mildew. This is a particularly critical issue during the flowering stages, when high levels of moisture can increase the risk of molds and mildew, including the notorious Botrytis that causes bud rot.
The ideal humidity for a cannabis grow room is between 40-55%. This reduces the chances of mold, powdery mildew and Botrytis developing, while allowing your buds to get the most resin out of them possible. Some growers lower their cannabis rooms to 40% or less during the final stages of flowering, but that can stress many plants and cause them to suffer from a lack of quality resin.
