Skip to main content

There are 6 essential needs for growing marijuana.

1. Light (must be the right amount, and the right spectrum or spectrums)

2. Air (oxygen and carbon dioxide)

3. Nutrients (needs to be adequate and the right sort)

4. Water (must have enough, but not too much)

5. Warmth (must be the right temperature range)

6. Grow Medium (what you will be growing in)

These 6 things are essential for all plant growth, not just cannabis. If you’re lacking in one of these things, your plants will suffer. Let’s take a deeper look at these necessary areas.

Needs For Growing Marijuana


Plants need light to form carbohydrates for building and repairing their tissue.  In nature, the sun gives a mix of all spectrums of light.

Indoors, when growing cannabis, the plants use mainly blue and red colors of light. Typically “Compact Fluorescent Lights” (CFL’s) are used for the seedling stage. “Metal Halide” (MH) lights are used to the vegetative phase of growth.

And “High Pressure Sodium” (HPS) bulbs are used for the flowering phase.  In addition, “Light Emitting Diode” LED lights are also becoming more and more common with cannabis growers.


Plants require a fresh supply of air in order to grow. If growing indoors, it is imperative to supply free flowing air for your cannabis plants.

Outdoors there is always an abundance of fresh air for the plants.

It is the indoor growers job to try to replicate the outdoor atmosphere.  Fans are imperative in any indoor grow room.  HPS and MH lights will raise the room temperature.

CFLs and LEDs do not dramatically raise the temperature of the grow area because they give off less heat. Exhaust systems with air-cooled grow lights are usually enough to keep a room at a sufficient temperature.  Heaters or coolers can also be used to bring the temperature to the proper levels.

The optimum humidity levels for indoor cannabis growing are from 40-60%. When humidity rises up to high levels, such as above 60-70%, problems with mildew and mold are likely to occur.

If you notice that your grow room is either very dry or very humid, the use of either a humidifier or a dehumidifier is recommended. It is common to lower the humidity level in a grow-room with a dehumidifier during the last two weeks before it is time to harvest the crop.

This process increases resin production, helps prevent mold, and gets the buds ready for drying/curing. The humidity level during the last 2 weeks can be dropped as low as possible.  A thermometer with a humidity sensor is essential in any indoor grow room.


Marijuana plants break down their food they receive by using “photosynthesis”. Nutrients are taken up from the soil by plants.

Fertilizers are added when the soil nutrients are low. Fertilizers can be chemical or organic, liquid or powder, and usually contain a mixture of ingredients. Commercial fertilizers indicate the levels of “NPK” (nitrogen, phosphorus, and potassium).

During the vegetative stage, cannabis needs more N than P and K, while during the flowering stage, P is more essential than N and K. Because Cannabis nutrient needs vary widely depending on the variety, fertilizers are often used sparingly and by trial and error.

Fortunately there are soils made that contain everything in them that are needed and simplify things for any grower. Such soils are simply add water and watch the plants grow!


Cannabis plants, like humans, are made up primarily of water.  The water is used to send nutrients to different areas throughout, and also to maintain a cool temperature.

Some growers use tap water, while others believe distilled water or reverse osmosis water (filtered) works better. It is our experience that tap water is usually fine for indoor cannabis growing unless the water is highly polluted.

Try to maintain pH for best results, 6.0-7.0 when using soil and 5.5-6.5 for hydroponic growing.


A cannabis plant needs warmth to properly grow. If temperatures are too low, the plant may not grow at all. The roots of cannabis plants like to be at a lower temperature than the leaves and buds of the plant do, about 10 degrees cooler.

Cannabis plants generally respond best in temperatures between 72-80 degrees Fahrenheit. (21.11 to 26.67 Celsius)

Room temperature or slightly warmer is perfect during the day and at night the plants need to be kept from getting too cold as the temperatures drop.

Grow Medium

By “grow medium” we mean, what you are going to grow in. There are numerous choices when it comes to what to grow cannabis in as you will see when you visit your local hydroponic store, there are hundreds of different mixes, brands, and bottles all claiming to provide exactly what your plants need to live.

Grow mediums are designed to help hold up the weight of the plant, while at the same time providing a stable base for the plant to grow roots in.

One of the most common questions for any cannabis grower is “What should I grow my plants with?”

There are over 300,000 jobs in the cannabis industry. CTU trained me for one of them!

marijuana extraction course - Johanna Rose
Makes $24.50 @ THC +

There are many options to grow with, and many different opinions of which one is best. One of the fun things about growing cannabis is experimenting with different techniques and finding the one you feel most comfortable with. Some ways of growing cannabis can be messy, like if you use soil indoors.

If you are the type of person who doesn’t want dirt under your fingernails, then using soil may not be your best grow medium to use.

These needs for growing marijuana are imperative for anyone interested in growing their own cannabis.

To learn which nutrients we recommend for massive cannabis yields and more potent buds, make sure to follow the Cannabis Training University blog.

Luis Cordova
Luis Cordova

Luis Cordova is a distinguished author, and renowned expert in cannabis cultivation, who possesses a Master's degree in Plant Biotechnology and Pharmaceutical Science. As a valued contributor to highly esteemed publications such as Cannabis Training University and Maximum Yield Magazine, Luis has emerged as a trusted source of guidance and knowledge in the cannabis industry. Having written thousands of informative articles, Luis is widely recognized for his comprehensive expertise on cultivating cannabis, both indoors and outdoors.

Enroll Now