The Ideal Environment for Growing Marijuana

If you treat your cannabis plants right, they will reward you with great buds at the end of your grow when you harvest. You risk shocking your marijuana if you do not control certain environmental factors imperative for healthy cannabis growth. Environmental shock is never a good thing for your weed plants!

What are the biggest factors to consider when creating the most ideal growing environment for your cannabis?

The following three factors are very basic and super significant in controlling when you are growing marijuana indoors:

  • Light
  • Temperature
  • Humidity / Air Flow


Photosynthesis allows your weed plants to use light and convert it into energy that is necessary for healthy growth. The more light energy or photons that your marijuana plants absorb during their growth, the bigger your cannabis buds will grow. The amount of light that you shine on your weed will have a huge impact on your bud yields at the end of harvest.

It is also important to know that your cannabis plants will use different shades of the light spectrum during its growth phases. When your marijuana is in its vegetative phase, your plants will use more “blue” light that will help it grow strong stems and as many leaves as possible. After you “flip” your lights to a 12 hour photo light cycle, your marijuana will start to mature sexually and will start to produce buds. When your cannabis plants are in the flowering period, they will require more red light for healthy bud development.


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Summary of Blue/Red Light needed for your marijuana plants:

  • Cannabis in Vegetative Phase – needs “blue” (range: 400 – 500nm; ideal – 460nm)
  • Cannabis in Flowering Phase – needs “red” (range: 620 – 780nm; ideal – 660nm)

It is important to keep a recommended distance from the bulbs from your lighting in your marijuana grow room. You should keep the top of your cannabis plants the right distance away from your bulbs. Some lighting systems are more powerful than others so the distance needed to keep your plants away from the lights will vary. For some HPS lighting, a good distance to keep your light bulbs up away from your cannabis plants is the distance from your elbow to the tip of your fingers. If you are unsure for your lighting system, you should ask a knowledgeable employee working in a hydroponic / nutrient store.


Your marijuana plants will like the temperature in your grow room if you do. Cannabis likes to grow in comfortable room temperatures. Generally, this ideal temperature is 70-85°F (20-30°C) but you will want to lower the temperature to 65-80°F (18-26°C) when your cannabis plants enter flowering and start producing buds. Photosynthesis will start slowing down for your weed plants with temperatures greater than 85°F degrees and this will negatively impact your bud yield. Your lights will produce heat so it is more likely you will be trying to make your marijuana grow room cooler and not hotter. It is strongly recommended that marijuana growers buy an atmospheric controller that will control the temperature and humidity in your cannabis grow room.

When do you want to lower temperatures for your cannabis?

Cannabis will require slightly different temperatures depending on what growth phase it is in. If your marijuana plants are or in early veg or in early stages of growth, you can have warmer and more humid conditions. The early growth of the cannabis plant occurs well, in humid conditions and higher temperatures. However as your weed plants start to mature and enter the flowering phase, you will want to decrease temperatures and humidity.

Humidity / Air Flow

Humidity refers to the presence of water vapors in the air. It is often expressed as a percentage of the maximum humidity possible at a particular temperature. The measurement is termed as relative humidity (RH). Your humidity should be the highest when your cannabis in their initial growth stages and should decrease when your weed plants start to flower. Having high humidity while your cannabis is producing buds can lead to bud rot.

What should my humidity be when I am growing weed indoors?

  • When your marijuana plants are in vegetative phase you will want 40 – 60%.
  • When your marijuana plants are in flowering phase you will want 40 – 50%.


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What is transpiration and why is it important for my marijuana plants?

All plants transpire which is their way of sweating and cannabis is no exception. transpiration from your weed plants will create moisture which increases humidity. This becomes even more prevalent as your marijuana plants grow bigger and get closer to harvest. This is why it is important to have ample ventilation for growing healthy marijuana plants. Good air flow also creates wind resistance and forces your cannabis to grow stronger stems. Good ventilation is also very important in the flowering phase as it will reduce the chances of you getting mold or Bud rot as you get closer to harvest. A good way to create air flow in your grow room is with oscillating fans.

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