In order to develop correctly, cannabis plants need certain humidity, temperature and pH conditions (acidity), as well as certain nutrients. If your plants don’t have the right conditions, they won’t be able to absorb nutrients properly and they’ll also be more susceptible to issues such as fungi and pathogens. In this section we’re going to explain the ideal cannabis growing parameters and how to achieve them.
Parameters Needed for Indoor Growing
When growing cannabis you’ll need to keep 4 main parameters in mind so that everything goes smoothly: temperature, humidity, pH and EC (Electroconductivity).
- The wrong temperature and humidity level can stop your plants from growing altogether and even increase the likelihood of fungal infections.
- pH measures the acidity in any given solution. The nutrients your plants absorb are only available within certain pH levels depending on the substrate; the wrong pH levels can cause your plants to suffer nutrient deficiencies and stop feeding.
- EC or electroconductivity measures the amount of dissolved salts and minerals in your water, which is necessary when using mineral fertilizers. However, when using biomineral or bio fertilizers you should follow the included feeding schedule. If you use water that has been through an osmosis filter, you’ll need to rebuild it before using it, and you’ll need an EC meter in order to add the correct amount of calcium and magnesium.
Parameters Depending on Plant Stage
The parameters we just mentioned can vary slightly depending on the phase that your cannabis plants are in. Let’s have a look at how you should adjust these parameters in order to guarantee successful plants.
Initial phase: Seedlings
This stage happens from the moment your seed sprouts until it grows its first real pair of leaves (with serrated edges).
- Temperature: 24 – 26°C
- Humidity: 65 – 75%. If you’re growing using clones we recommend increasing humidity to 75 – 85% the first week, and reducing it to 65 – 75% the second week.
- pH: adjust your pH levels to 6 in soil and 5.5 in coco coir and hydroponics.
- EC: during this stage your plants shouldn’t need any fertilizer if you’re growing in soil, and around 0.3 if you’re growing in coco coir or hydroponics.
Vegetative or Growth Stage
By growth we’re referring to the stage in which your plant goes from having its first pair of real leaves until the flowering stage starts.
- Temperature: 22 – 26°C, four degrees lower when the lights are off.
- Humidity: 50 – 60%
- pH: keep pH levels at 6 in soil and 5.5 in hydroponics. As the weeks go on, we recommend increasing it to 6.4 in soil and 5.8 in coco coir and hydroponics.
- EC: in soil and coco, 0.8 – 0.9, and increase to 1.1 – 1.2 during the growth stage. In hydro we recommend an EC of 0.5 – 0.8 and increasing it to 1.1 – 1.3 depending on the strain being grown.
First Flowering Stage
During this stage, your plants will begin to flower and show their buds.
- Temperature: 20 – 25°C
- Humidity: 40 – 50%
- pH: when growing in soil, we recommend starting with 6.4 and progressively increasing it each week until it’s at around 7. In coco coir and hydroponics, adjust pH levels to 5.9 and increase them to 6.4 slowly.
- EC: in soil and coco coir, start the flowering period with an EC of 1.2 – 1.3, and then increase it weekly until it reaches 1.9 – 2.0. In hydroponic grows you can start off with 1.3 – 1.4 during the first few flowering weeks, and increase it to 2.0 – 2.2.
Advanced Flowering Stage
During this stage, your cannabis plants’ buds have already developed and are beginning to fatten up.
- Temperature: 18 – 24°C
- Humidity: 30 – 40%
- pH: 7 in soil, 6.5 in coco coir
- EC: in soil and coco coir grows, 1.9 – 2.0, and in hydroponic grows it should be at 2.0 – 2.2. During the last few growing days we recommend watering using just water in order to get rid of excess minerals and salts in your substrate, improving the flavour of your harvest.
How to Measure Temperature, Humidity, pH and EC in Indoor Grows
We recommend checking out our meter section, where you can find a wide range of pH and EC meters, as well as temperature and humidity meters, pipettes and measuring cups. In order to measure temperature and humidity, we recommend getting a digital thermohygrometer which also indicates the max and minimum readings. In order to control pH levels, you can use portable digital meters such as the Hi 98107 by Hanna Instruments or the Hanna pH Grocheck meter, which is ideal for hydroponic tanks. In order to measure your plants’ EC you can use the Hanna HI98304, an affordable portable meter that’s high in quality, or the continuous EC Hanna Grocheck Meter for water tanks.
How to Control Humidity in an Indoor Grow
Keeping humidity levels within the required parameters when growing cannabis is absolutely necessary if you don’t want to deal with fungal infections; high humidity and dense buds are a lethal combination.
In our Humidity Control section, you’ll be able to find everything you need to make sure your plants are well within the necessary parameters.
For example, the Cornwall Humidity Controller, a highly useful digital accessory that can turn your humidifier or dehumidifier on or off, depending on your needs.
We also have a wide range of humidifiers and dehumidifiers in case your ventilation and air extraction system isn’t enough to keep your grow room within recommended humidity levels. A good example of this is the silent Pure Factory 8L Humidifier, which uses ultrasonic technology, or the Mistmaker, which comes with 1 or 5 membranes, producing a humid, cold mist.
We also have some of the best dehumidifiers on the market, such as the Mini Cornwall Dehumidifier which uses Peltier technology, making it ideal for small spaces, or the Industrial DH-202B by Pure Factory, which reduces humidity in large grow rooms efficiently and can absorb up to 20L a day. The 504B by Pure Factory is designed for grow rooms, reducing humidity by up to 50L a day in order to cover 50 – 70m2.
Automatic Growing, the Next Step
In our automatic growing section you’ll be able to find everything you need to set up a professional grow room; timed boxes for timing various lighting systems, humidity and temperature controllers capable of automatically adjusting ventilation and extractor fans, watering timers etc.
If you have any questions regarding accessories and devices needed to control indoor growing climates, get in touch with La Huerta Grow Shop’s team of professionals.