How To Grow Marijuana Indoors: Beginners Guide

From a basic view growing indoors is easy. Just make sure you have a secure location, plant good seeds or clones, a proper climate – air, light, water, nutrient, drainage and growing medium. Once planted seeds will begin their life cycle and turn into seedlings and then put on vegetative growth. At the end of the vegetative growth stage they will show male or female pre-flowers. When the flowering stage is induced, your plants will ready to harvest in about two months.

What do I need?


Marijuana seeds (aka cannabis seeds) are easy to purchase online or by mail. Many seed companies advertise in magazines like High Times, Cannabis Culture, Weed World etc. You can also get them from websites like Attitude Seed Bank or Nirvana Shop. You may even find seeds in a good bud from time to time.


Clones are exact replications of a female marijuana plant that has been cut from a branch tip and rooted. They are desirable because they flower sooner than seeds and are guaranteed females. Harvesting clones can be accomplished in about three months. Unfortunately, clones are not available by mail delivery. They must be purchased from a grower. A Google search for “buy clones online” will give you a list of potential growers you can get in contact with.

Grow Space

Where can I grow marijuana?

It’s possible to find a grow space in almost any home or structure. The ideal space should be enclosed so you can control the environment where the plants will grow. Some of the more popular options are in the corner of a basement, attic, closet or extra bedroom. Enclose the space with wood, brick, plastic or a prefabricated grow tent or cabinet.

Temperature Control

It goes without saying that the temperature and humidity in the grow space must be controlled. Optimal temperature for growth is about 75F (24C). Ideal humidity for growth is 50-70 percent during pre-flowering stage and 50 percent during flowering stage. The environment will most likely need to be heated or cooled slightly to maintain the ideal temperature and humidity. In many cases a ventilation face is the perfect solution to keep the ideal temperature and humidity.

Air Circulation

Circulating air with an oscillating fan provides the benefit of mixing the hot air on top with the cool air below so temperatures are more even throughout the room. More importantly, it allows the leaves to come in contact with new CO2. CO2 is used by the plant during photosynthesis to produce sugar for food.

Air Ventilation

Marijuana uses the available CO2 in a room pretty quick. It’s recommended to have a ventilation fan that expels used CO2 and an intake vent that draws in fresh, cool, dry air rich in CO2.


Add light with fluorescent tubes, compact fluorescent lamps (CFLs), light-emitting diode (LED), metal halide lamps, or high pressure sodium (HPS) lamps. Each have their pros and cons. Fluorescent lights are best used for growing seedlings and clones. Affordable CFLs from about 65-125 watts are able to grow small crops from start to finish. More expensive and versatile LED lights are considered the grow light of the future by many growers and range in a variety of options. Metal halide and HPS lamps are high intensity discharge (HID) lamps are range from wattage and color spectrum.

Water and Drainage

Can I grow with tap water?

Normal tap water is usually okay to grow cannabis with. If you can drink it yourself, it’s usually okay for you plants. If your water is rich in sodium, other minerals or taste bad, you may need to treat it with reverse osmosis. Such actions are not typical. Make sure the container you’re growing in does not hold the water and will drain from the bottom when poured.

Growing Medium


“Hydroponics” refers to growing in a soil-less blend that serves as an anchor for the plant roots. It allows for more accurate nutrient (fertilizer) uptake by giving growers more control over how much the plant receives. Hydroponic grow systems give the roots more airspace and allows for faster nutrient uptake than traditional soil gardens. There are a number of different hydroponic systems ranging from simple and cheap to complex and expensive.


Growing in soil is easy and simple. Many professionals recommend purchasing quality soil that drains well. In the event that you cannot find good soil, mix our own from quality ingredients. Organic soil gardens tend to flaunt the best aroma and flavor.