A Beginner’s Guide to Growing Cannabis Indoors

There’s an overwhelming amount of information out there for first time cannabis growers. And the truth is, there are several approaches you can take to achieve success. But like any new hobbyist, you just need a way in. Time and experience will teach you more – for now, it’s about getting started.

Our guide to indoor cannabis growing breaks down the process into eight easy steps while hitting all the major considerations first time growers need to know. Dive in and happy growing.

No. 1 Pick Your Room or Space

You’ve got to have a place to put your plants, so selecting the best spot available to you is the first step. You don’t need to have a massive grow room to begin. A cabinet, closet, part of a basement, and spare room all work equally well. The key thing to remember about your selection is that you’ll need to select equipment and plants based on your space. And that can be budget driven.

We recommend that first timers start small.

  • The smaller, the less expensive to start
  • Mistakes won’t be as big
  • Growing a few plants is easier than growing a lot of plants

Growing pains are inevitable. Investing in 15 plants that you lose to disease or pests is much more costly than two.

But just because you want the physical space to be small, don’t limit your thinking. Your plants are (hopefully) going to grow and need to take up more space as they do. You also need to account for things like fans, lights, ducting, and possibly more. Don’t forget that you also need to be in the room or space and work with the plants – so consider the elbow room you’ll need.

Depending on the strain, some cannabis plants triple in size during the flowering stage. So give yourself plenty of room to grow into.

Cleanliness is King

When growing indoors, cleanliness is critical. Be sure to select a space that can be easily cleaned. Common household surfaces like drapes, carpet, and raw wood are difficult to keep clean so try to avoid them when possible.

Light-tight

If light leaks from your room during dark periods, your plants will get confused. When they get confused, they start producing male flowers. And this is not what you’re looking for. Make sure your space is light-tight.

Miscellaneous Considerations

Don’t forget to keep these things in mind when making a decision about your new grow space:

  • Temperature – Ideally you want a cool, dry area with easy access to fresh air. Warm and humid spaces will have the hardest grows.
  • Convenience – Monitoring plants is a key factor in success. Daily checking is required – and for newbies, you’ll want to check in several times a day. Don’t select a space that makes it a chore to check in.
  • Covertness – No matter where you live, stealth is a good rule of thumb when starting a grow. Fans can be loud, so try to select a spot that won’t attract too much attention.

No. 2 Pick Your Grow Lights

The environmental factor that will most affect the quantity and quality of your cannabis yield is your lights. This is where it’s a good idea to invest the most. There are a number of different lights commonly used for indoor growing.

HID Grow Lights

HID stands for high-intensity discharge. These are the industry standard. They provide a combination of efficiency, output, and value which is hard to beat. They are more costly than incandescent and fluorescent lights but give off much more light. A metal halide (MH) light produces a blue-ish white light and is used during vegetative growth. High-pressure sodium (HPS) lights are closer to the orange end of the spectrum are used during the flowering stage.

If you opt for HID lights, you’ll also need a ballast and a hood/reflector for each light. Be careful when purchasing these. Some ballasts are designed specifically for either MH or HPS lamps. Though newer designs are being made for both.

Other tips:

  • If both MH and HPS aren’t in your budget right now, start with HPS. You’ll get more light per watt.
  • Magnetic ballasts are cheaper but run hotter. They’re also less efficient.
  • Watch out for cheap digital ballasts. They aren’t always well shielded and can interfere with Wi-Fi
  • Air-cooled reflector hoods are your best bet.
  • HID produces a lot of heat, which means investing in ducting and exhaust fans. Tough on the wallet but necessary to control the temperature in your room.

Fluorescent Lights

Smaller growers seem to prefer the high-output (HO) T5 bulbs. They are a little cheaper because the bulb, ballast, and reflector are all sold as a unit and they don’t need a cooling system. The downside to fluorescent lights is that they are simply less efficient. You’re going to get about 20-30% less light per watt. In order to equal the output of one 600 watt HPS, you’ll need 19 four foot T5’s.

LED Lights

LED stands for light emitted diode and the technology has been around for a while now. LED makes for some incredibly efficient indoor growing lights. But they do cost. High quality LED’s will cost you ten times what you’d pay for HID. LED’s do last longer, use way less electricity, and offer a fuller spectrum of light. All of this can lead to bigger yields.

We recommend doing your research if you think this is the way you want to go. The market is saturated with poor quality LED systems for growers – be sure to read product reviews and talk to other growers if you can.

Induction Lights

Electrodeless fluorescent lamps have also been around awhile and have recently come into popularity with growers. An invention of Nikola Tesla, induction lights are a longer lasting and more efficient fluorescent light. Once again, it comes down to price. What are you aiming for and what do you need to spend to get there?

No. 3 Air

Much like people, plants need air. They need fresh air to really thrive and carbon dioxide for photosynthesis. Make sure the grow room you select has plenty of it. Exhaust fans are an easy way to achieve this. Install one near the top of your space in order to remove warmer air. Then install a filtered air inlet opposite the exhaust, near the floor.

The temperature should stay between 70 and 85 degrees Fahrenheit when the lights are on and 58 to 70 degrees Fahrenheit when they’re off. Indica strains prefer the low end of the range, while other strains easily tolerate the high end.

Determine the size of your exhaust fan by considering the size of your grow space and the lighting system that you’ve chosen. HID puts out a lot of heat (especially if you’re not using mounted air cooled hoods).

A good rule of thumb is to set up your lighting system and use it for a while, then decide what kind of exhaust fan and air filter system that you need. Also, if the odor of the plants in bloom will cause problems for you, add a charcoal filter to the fan.

You’re aiming to provide a constant light breeze for your plants. This helps create stronger plant stems and a less hospitable environment for pests and molds. An inexpensive fan mounted to a wall works great. Avoid windburn by pointing it away from the plants.

No. 4 Controls and Monitoring

Now it’s time to automate your climate control and lighting systems. You can imagine how sophisticated and expensive these systems can get. The upper end of the market will control temperature, light, CO2, and humidity. As a beginner, you just need a 24 hour timer for your light and a thermostat switch which you can adjust for your exhaust fan.

The timing you select for the light and dark cycle is key when growing cannabis. You want to keep your lights on 16-20 hours for every 24 hour cycle during the vegetative stage. When you want them to bloom, switch to a 12/12 cycle. Set your lights to turn on and off at the same time every day in order to avoid stressing the plants.

Helpful Devices

A basic thermostat adjuster allows you to set the device to your maximum desired temperature and then plug in your exhaust fan. When the temperature rises to the level you set, the adjuster turns the fan on until it cools by a few degrees. The perfect energy saver.

One thing that new growers find handy is a hygrometer/thermostat combination. Since you’re not likely to be spending all your time in the grow room, a device with a high/low memory feature will keep tabs on your rooms conditions. They’re relatively inexpensive and show you the highest, lowest, and current temperature and humidity levels.

Keep a pH meter nearby so that you can periodically check the pH level of your water, soil, and nutrient solution. Cannabis likes a pH level between six and seven for soil and 5.5 and 6.5 for hydroponic media. If the pH drifts outside of those ranges, you’re looking at a nutrient lockout. Your plants won’t absorb the needed nutrients.

No. 5 Pick Your Grow Medium

The beauty of indoor growing is that you have many methods to choose from. Everything from the straightforward pot and soil combination to a Rockwool slab to a hydroponic tray. Just like lights, each medium has pros and cons.

Soil

Traditional and forgiving, this is the ideal medium for new growers. Choose a high quality potting soil that doesn’t contain any artificial extended release fertilizer (think Miracle Gro). This is not good for growing cannabis.

Look for a pre-fertilized soil or super soil. This can grow a cannabis plant from start to finish without the need to add nutrients. You can also make your own super soil with bat guano, worm castings, and other compost. Let it sit for a few weeks after you put it all together before planting.

Hydroponics

Soilless is becoming more popular with cannabis growers. Using this method requires you to feed concentrated mineral salt solutions to the plant. The solution is absorbed through the root system by osmosis. This is the medium to use if you’re after the fastest growth and the biggest yield.

But you also have to develop the experience. Precision is required because hydroponic plants can be easily over and underfed.

You can use coco coir, Rockwool, clay pebbles, vermiculite, perlite, and more. Commercial mixes combine two or more of these to optimize growing. Plus, they are readily available.

If you choose hydroponics, you can automate your system or use hand-watered individual containers.

No. 6 Choose What to Grow the Cannabis In

This is a step that really builds on the decisions you’ve made in the first five steps. The kind of container that you’ll use will really depend on the medium you select, your system, and the plant size. If you’re going with flood and drain hydroponics, you might consider net pots filled with clay pebbles. But a super soil grow will need ten-gallon pots to support larger plants.

This is an area where inexpensive is ok. Consider disposable plastic bags, cloth bags, or regular flower pots. Some growers like to use smart pots – which are designed to enhance the flow of air to the root zone. A lot of newbies start with the old fashioned five-gallon bucket.

Keep drainage in mind though. Cannabis is sensitive to over watering. You don’t want to create waterlogged conditions in your containers. This is easily solved by drilling holes in the bottom of your buckets.

No. 7 Pick Your Nutrients and Feed Your Plants

Cannabis needs more fertilizer than other crops. There are several macro and micronutrients that they require:

  • Phosphorus (P)
  • Nitrogen (N)
  • Potassium (K)
  • Magnesium
  • Calcium
  • Iron
  • Copper

If you opt not to use a pre-fertilized super soil, you’ll need to feed the plants about once a week. You can buy fertilizer in concentrated liquids or powder form (that you might with water). These commercial products are usually formulated for vegetative or flower growth.

Most of the macronutrient solutions are sold as a two-part liquid. This keeps the solution from combining and precipitating (forming a solid unusable by a plant). So you’ll need two additional bottles for the vegetative cycle, two for the grow cycle, and a bottle for the micronutrients.

You might want to consider a calcium/magnesium supplement. Some strains need more of these micronutrients than others.

When you first begin feeding, start at half strength. Cannabis is easily burnt. In general, it’s worse to overfeed than underfeed. The key is to spend time learning to read your plants and getting to know what they need and when. This will come with experience.

No. 8 Water

Depending on your location, the kind of water you use may or may not be an issue.

  • Some areas have a high concentration of dissolved minerals. These can build up in the plant roots and create nutrient lockout.
  • Water can have fungus and pathogens that aren’t harmful to humans, but cause root disease in plants.
  • High levels of chlorine can harm the soil microbes.

For all of these reasons, the best bet is to filter the water you use for your cannabis. Water your plants based on the medium, plant size, and ambient temperatures. If you like, you can wait until you notice the lower leaves beginning to drop a bit.

The most important part is not to overwater. It’s also the most common mistake that beginners make. The reason for this is that there are so many variables to consider when it comes to watering and because it really does take learning by trial and error.

Hopefully this gives you some idea of where to start. From here, you’ve still got to make decisions about which strains you’ll grow, what techniques you’ll use, and how to troubleshoot grow problems. Time and attention will get you far as you move from newbie to pro.