A Beginner’s Guide to Growing Cannabis Indoors
While it might seem daunting at first, growing marijuana indoors isn’t really that difficult, as Tony van Liefde explains. If you’ve never tried growing cannabis before and want to give it a shot, just follow his recommendations and you’ll be amazed at the results.
Growing cannabis indoors is not difficult these days. There are lots of strains which are bred to give great results. And there are lots of options for grow methods and lights. If you have never grown weed inside before, you will be faced with a confusing number of options, but the key is focusing on a few simple recommendations which will allow you to make a successful first grow indoors.
Where to Grow?
One of the easiest ways to start is with one of the purpose-built indoor grow tents available from numerous vendors. These tents are strong and can be assembled in a few minutes. They are light proof and come with all the necessary holes for cables and air extraction. Indoor grow tents cost around $100-$150 for a basic model.
Grow in Soil or Hydroponically?
Cannabis can successfully grow in several different ways. Perhaps the simplest method is in soil. But it will grow well in coco fiber, clay pebbles, rockwool, and any number of different hydroponic systems where there is no soil. All that matters is the roots get nutrients and oxygen. It is called weed for a good reason.
(For more on hydroponics, check out Growing 101: Choosing a Hydroponic System)
Soil for Simplicity
Growing in hydroponic systems does give great results but the additional technical aspects involving pH, electrical conductivity, etc. may be a bit confusing for some first-time growers, so we will start by looking just at growing in soil.
The simplest way to start growing is to buy a prepared specialist soil from companies like BioBizz, Canna, or Plagron. This isn’t the cheapest way of getting started but it is the simplest, as everything is done for you, plus you know the soil will give solid results. If you visit their websites, you will see they have soil for seedlings and soil to use when potting up plants into their final containers. They also have additional soil additives which you may want to consider so you can maximize yields, including extra nutrients for flowering. If you buy compost, then add at least 30 percent perlite to allow root aeration. If you can, add some worm castings or other light soil enrichers such as bat guano. The easiest way to start is to get a specialized, ready-mixed soil and large plant containers.
If you use large containers, say four or five gallons, with a prepared soil mix, you will have a very simple way of growing. You won’t need to worry about pH or nutrient deficiencies. The only thing you will need to do is water them lightly a couple of times a week and perhaps add a little liquid feed towards the end of flowering when the soil nutrients are getting depleted. The most common mistakes made by new growers are overwatering and over-feeding; both of these slow plant growth and limit your end result.
Keep the growroom temperature around 77°F. If it gets too hot (more than 86°F) or too cold (less than 68°F) you may start seeing slow growth and other unwanted issues. If you are growing in a tent you will need to extract the air from the tent. Air is removed by a fan which sucks the air through tubes (usually four inches in diameter). The air should also be sent through a carbon filter to remove all traces of the characteristic cannabis smell. Finally, the extracted air is usually vented outside or into a well-ventilated loft. Pro growers will use ozone generators to remove the tiniest remaining canna smells. If you are growing indoors, then you really must use carbon filters. Cannabis plants need a constant supply of fresh air to stay healthy and grow large.
Choosing the Seeds
You have two choices. You can grow autoflowering seeds or traditional photoperiod strains. Autoflower seeds take 70 days from sprouting the seed to harvest under a lighting regime of 20 hours on, four hours off.
Traditional strains are grown initially under 18 hours lights on/six hours off. This is called vegetative growth; the plants grow leaves, roots, and branches but no bud. Usually, after four or five weeks, the plants are switched to 12 hours lights on/12 hours off. This causes the cannabis plant to go into flowering and produce the buds we all love. Normally, the flowering process takes around nine weeks. The finished plant is cut down, and the buds are trimmed and dried for a few days. Usually, people cure (or mature) the buds in glass jars for a month or two to get the best flavors.
Cannabis plants can be male or female, but only the female plant has the buds you want. For that reason, you are better off with feminized seed which will give rise to more than 95 percent female plants. If you are new to growing, try and purchase a robust, forgiving seed variety from a seed bank you can trust.
(For more on cannabis seeds, read Weed Seeds: When to Choose Regular, Feminized or Autoflowering.)
Most indoor growers use high-pressure sodium (HPS) lights as they are a low cost and effective way of growing. Light emitting diode (LED) lights deliver incredible results but they are still a little too expensive for many people. If you buy a grow tent you will normally get a manufacturer’s recommendation about the size of lamp and size of extraction fan. The most common HPS lamps are 250W, 400W, and 600W. The more power they have, the more light (and heat) they produce.
That’s it. There are countless ways to grow cannabis, but growing in premixed soil, in a purpose-built indoor tent with an HPS light is one of the easiest ways to start. More advanced growers will tell you hydroponic systems such as nutrient film technique and deep water culture give even better results than soil once, but it is best to learn the basics before starting more sophisticated grows.
Written by Tony van Liefde | Breeder
Tony van Liefde has been part of the Dutch Passion Seed Company for 10 years, with a lifelong love of the cannabis plant and cannabis breeding. He has a particular interest in the evolution of autoflowering cannabis, selective breeding of varieties rich in minor cannabinoids, and unusual genetic lines. His ambition is to see cannabis widely legalized and made available as a mainstream medicine.