Temperature and Humidity

In order for cannabis plants to grow correctly without any illnesses or issues they need the correct temperature and humidity parameters, among others.

These parameters can vary as your cannabis plants grow.

Making sure to maintain a stable climate in your grow tent for your plants within each of their stages is key to having highly successful plants.

The Importance of Temperature and Humidity in Indoor Grows

• Bad air circulation in your grow room or grow tent can increase humidity and cause a fungal infection when your flowers are doing their best.
• High temperatures during the flowering period can easily lower the final quality of your yields by quite a lot. The flowers closest to the lights, which are generally the largest, are those which are under the most risk of losing flavour due to excess temperature.
• Knowing the right humidity and temperature levels for your grow allows you to point your grow in the right direction, allowing you to adapt all parameters to your plants’ needs at all times.
• Increasing extraction, placing your fans, or adjusting the height of your plants’ lights are all chores that require a thermos-hygrometer to do properly.

The Ideal Temperature and Humidity for Indoor Cannabis Grows

The recommended temperature and humidity parameters for cannabis plants don’t stay the same during the entire growing process. You'll need to adapt these parameters to each stage of your plants' life cycle.

In order to simplify this we’ve divided it into 4 stages. Temperature and humidity changes should be progressive, which is to say, a little bit every day.

These numbers indicate the recommended parameters for your grow room; lower the humidity slowly, as well as the temperature, until you get to the right parameters for that stage of growth.

Sowing

During the first days, your plants haven’t developed enough root mass in order to absorb enough water. They need a humid and moist environment in order to stay hydrated and start growing. During these days we recommend keeping the temperature between 24 and 26 degrees, with a humidity of around 65 – 75%. Your plants are still quite small in this phase, so you can easily achieve these parameters using a propagator.

Growth or Veg Stage

This stage starts once your plants have their first pair of real leaves, which are those which have serrated edges and come up after the first two round leaves. This stage goes on until the flowering stage begins, when your plants stretch out before they start producing flowers. During this stage, your plants’ roots will have colonized the entire substrate, so you’ll have to reduce humidity levels to around 50-60%. The recommended temperature is between 22 and 26°C, with 28 as the max.

First Flowering Stage

This is when your plants grow and stretch out, and they start producing groups of pistils (the little hairs on the flowers). Towards the end of this stage, your plants will start growing their first buds. During this stage you’ll need to reduce humidity to 40 – 50% and the temperature to around 20 – 25°C.

Advanced Flowering Stage

The buds should have been formed at this stage and they’ll begin fattening. It’s important to keep in mind that the temperature shouldn’t go over 26°C; if this happens, terpenes will begin evaporating and the flowers can end up losing aroma and flavour. Plus, you’ll also need to make sure that humidity at this time doesn’t go over 40%; this is important in order to make sure that fungal infections such as botrytis which deeply affect denser flowers. Make sure you have the right type of ventilation and that no stagnant air is forming among your plants. The recommended temperature should be 18°C with lights off, and 24°C with lights on. Humidity should be between 30% and 40%.

How to Measure Temperature and Humidity

You’ll need to know the temperature and humidity in order to effectively administer the ventilation and extraction in your grow room. Our sensor thermo-hygrometer is a great tool that can help you figure out what’s going on in your grow tent when you’re not there. The recordings are stored at min and max values, so you can get a general idea of your grow’s parameters.

How to Control Humidity and Temperature in your Grow Tent

In order to make life easier, it’s a great idea to set up certain systems to work automatically when it comes to temperature and humidity changes that can affect your plants. Humidity and temperature controllers allow you to automatically turn on your dehumidifier, humidifier, heat cables etc, keeping your grow within the right parameters.

In order to fully automize your fans and extractors you can use a fan controller, which is the most professional option. Fan controllers allow you to adjust your fans and extractors automatically, depending on the chosen model, and working with changes in humidity, temperature, ventilation etc.

If you have any questions regarding the products involved in measuring and controlling humidity and temperature, at La Huerta Grow Shop we have professionals that are ready to help you out.