How to Grow Marijuana Indoors: A Step-By-Step Guide

By Alex Halperin May 15, 2020

The way to grow marijuana indoors is a bit different than growing any other kind of herb garden, but at the end of the day, the process is not as intimidating as it may seem. Whether you’re looking to try out a plant or two, or exploring a bigger operation, this article can be your roadmap for growing weed in the great indoors.  

Why Would You Grow Marijuana?   

By growing the green, you can save it: cutting out the middleman and essentially becoming your own dealer means your marijuana will be much cheaper. You’ll also have far greater control over your own product, allowing you to tailor it to your individual needs and preferences. 

For example, deciding to growing organic crops free of pesticides can be a real bonus for your body. Plus, like any kind of gardening, growing weed can be a great hobby, producing gratifying results especially as you hone your skills and knowledge of this fascinating plant. 

How Long Does it Take to Grow Marijuana Indoors?   

The length of time it takes to go from seed to weed can vary widely, but generally the timeline is between three to five months. This timeline accounts for the four basic life stages of the plant: Germination takes between one to seven days; The vegetative stage lasts between three to eight weeks; and flowering can take upwards of 16 weeks. The harvesting stage, including the drying and curing processes, can take up to a month. 

These timelines are affected by a number of different factors, including the chosen strain, growing methods and equipment being used, as well as how many plants are being grown. 

Benefits of Growing Weed Indoors   

To grow marijuana indoors or outdoors, that is the question. There are benefits to both. However, indoor environments offer a few key advantages. Indoor grows can happen all year round, making it possible to get up to six harvests per year, rather than needing to wait out winters and other unfavorable seasons, particularly in northern latitudes.  (It should be noted that it can take time, dedication and experience to achieve this many harvests in a year.). 

Indoor grows also allow for more control over the growing environment. Cleanliness is a huge factor in any successful operation, and indoor spaces enable a level of hygiene that can eliminate potential contaminants. Air pollution, fungus and other factors can cause disease or otherwise negatively affect plants. 

But this also means that indoor gardeners are entirely responsible for the health and well-being of the plants. Indoor growers need to provide the perfect amount of inputs like water, light, ventilation, gas exchange and fertilizers that the great outdoors may provide naturally. The good news is pot plants tends to enjoy the same temperatures as people, between  68-77 degrees Fahrenheit – so they can make great roommates. It’s also possible to keep indoor operations out of public view, which can be advantageous for security reasons – and to prevent any unauthorized harvests. 

Step 1: Choose Your Marijuana Strain   

Cannabis sativa strains come in all different shapes and sizes. For indoor grows, it’s best to think about what your goals are and what space you are working with in order to achieve the best results. Some strains offer high yields and short flowering periods, but may require more space in order to achieve maximum results. Also important to consider is the grower’s preference between indica and sativa, which will come down to the kind of experience you want from your finished product. 

Once the strain is chosen, the next step is to decide whether to grow from seeds or clones. Below are some factors to consider: 

Grow Marijuana Indoors with Seeds

Growing from seeds is the way nature intended it, and can result in a heartier, healthier plant in the long run. Purchasing feminized seeds also guarantees plants are female, and therefore will produce buds (male plants are unable to produce buds). 

Grow Marijuana Indoors with Clones

Although it may seem counterintuitive, since they are already partially-grown plants, clones tend to be more temperamental and therefore challenging to grow successfully, especially for beginners. 

Clones can go through various traumas which render them more susceptible to disease and other ailments. Repotting is always shocking for plants regardless of species, since uprooting them and changing their location is an unnatural process they haven’t evolved to endure. Repotted plants need extra care and attention, which first-time growers may find difficult. Transporting clones may cause stress and even death. While purchasing a clone may reduce the total grow time, there tends to be a greater chance for problems down the line.

Step 2: Designate a Space to grow marijuana indoors  

One of the first considerations for selecting a space is size. Cannabis plants can be long and tall or squat with broad leaves, so be sure to get a sense for what the crop will require. For one or two plants, a smaller space such as a closet can work well. However it’s important to be able to maneuver between or around each plant for inspection, to keep an eye out for health issues. 

Plants housed too close together may also facilitate the growth of mold. According to Growers Choice Seeds, a 2×2 foot area can hold up to 16 plants, but generally it’s best to give each plant some space to breathe. The more plants, the more space required. 

Cleanliness is a another critical factor to keep in mind. Avoid using carpeted spaces, since carpets can harbor dust, mold and other potential contaminants. Even wood should be avoided if possible for its absorptive surfaces. Ideal materials include linoleum or concrete.

Selecting a self-enclosed space allows for better control over light, humidity and other factors that are critical to properly moderate throughout the plant’s lifetime. 

Step 3: Choosing Your Medium   

Selecting the method for growing plants comes down to the amount of time and money one is willing to invest, as well as a few other factors. Here are some benefits to consider for each medium: 

Grow Marijuana Indoors with Soil

Because it’s natural and easy to use, soil can be a great option for beginners. Soil tends to produce higher yields than hydroponics, enabling plants to grow bigger and taller. Many soil mixes include fertilizers by default. This means plants require fewer additives, especially in the first few weeks. 

Soil also acts as a buffer, since it enables slower assimilation of elements, and the pH is more stable than other growing mediums, providing a larger margin of error.

Grow Marijuana Indoors with Hydroponics

This usually refers to a soil-free method of growing plants where their root system is submerged in water. This medium can facilitate the easiest and greatest degree of control over nutrient and water delivery, and can enable fast growth of plants with highest cannabinoid yields. 

Popular forms of hydroponic grows include Deep Water Culture, aquaponics, in which plants are grown in tanks with fish, and Nutrient Film Technique. 

Grow Marijuana Indoors with Coco

Also known as coco coir, coco is coconut fibre, which can either be mixed into soil or used as a stand-alone medium. It is great for water retention, meaning less watering is required, and it possesses good buffering properties as well. Pest infestations are also less likely to occur in a soilless mixture like coco. 

Step 4: Choose Your Cannabis Grow Lights   

Of the many different types of grow lights, three are the most common and popular. High Intensity Discharge (HID) lights are preferred for professional or commercial growers, since they offer the diversity of wavelengths needed throughout the different cycles of a plant’s life. However, each HID emits a certain frequency, so different HID lights would need to be purchased for each stage of the plant’s life.  HIDs emit vast amounts of light but also heat. This can require cooling fans and lead to higher energy use costs. 

Compact Fluorescent Lamps (CFLs) might be cumbersome in size and reminiscent of depressing office environments, but they are energy efficient and particularly good for plants in the early stages of their lives. Light Emitting Diodes (LEDs) are the most energy efficient. Generally, LEDs should be set about 12-18 inches or more above plants.  

Step 5: Ventilation   

Plants can’t grow in a vacuum. Effective indoor grow environments must  mimic the great outdoors as much as possible. This includes the gentle spring breezes all plants seem to love. 

A typical ventilation system will include up to three pieces of equipment. The most important is the extractor fan, which turns over the air in the space and helps regulate the internal climate. An intractor fan can be useful to counteract air pressure caused by the extractor, particularly when your growing space is a tent, where such air pressure can cause tent walls to collapse. Finally, an interior fan can help circulate air around the space. 

Step 6: Pick Your Climate Controls and Monitors   

Maintaining a consistent and optimal environment for your ganga garden is critical, yet this can be difficult to do, especially for beginners. Many products exist that can measure crucial factors like humidity and CO2 levels, and provide alerts about any dips or spikes. pH monitoring systems are also available and worthy of investment. 

Step 7: Pick a Container   

Containers have come a long way from the standard plastic or terracotta pots – however these can be great options for your cannabis. Other options include fabric pots, which make overwatering much less of a risk. 

That is key since it is more difficult to recover from over watering than underwatering. Hemp buckets, which include space at the bottom to act as a nutrient reservoir, meaning watering can be done less often. Air pots are another option. These enable “air-pruning”, a natural process that occurs when roots come into contact with air. Be aware that air pots tend to dry out quickly and require plenty of watering attention.  

Step 8: Feed Your Cannabis Plants Nutrients   

Plants can be fussy eaters, and cannabis is no exception. Over-feeding, or feeding them the wrong thing at the wrong time, can cause serious harm to your garden. 

Everything needed for marijauna to thrive exists in soil, air, and water; this is why soil-grow mediums are so effective, and why hydroponics – where all nutrients must largely be added by the gardener – can go wrong without careful attention and study. 

Store-bought fertilizers contain the primary essential elements of nitrogen, phosphorus, and potassium, along with other micronutrients. Often, store-bought fertilizers will indicate how much to feed to apply at what stage of the plant’s life cycles. 

Step 9: Water Your Cannabis Plants   

Watering cannabis plants can be tricky. It is not only the amount of water that is important, but the pH levels as well. While watering needs differ depending on the substrate, setup and more, it is generally advised to water every two to three days, and to do so in the morning or when artificial lighting is first turned on. 

Gauging when to water is important part of the growing process. For soil growth mediums, simply lift up the pots; if they are light, then they need water, whereas if they feel bottom-heavy, hold off. For coco and hydroponic grows, an eye towards plant behavior post-watering (such as curling leaves, yellowing tips or drooping plants) can be a way of telling what’s needed moving forward. 

Step 10: The Vegetative Stage   

Think of the vegetative stages as the childhood and teenage years of a plant, where they grow tall and fill out with leaves and stems. This stage can take anywhere from three to 16 weeks, and ends when flowers begin to appear. Plants require more watering during the vegetative stage than in the flowering stage. Fertilizing with higher levels of nitrogen and potassium, with a more moderate rate of phosphorus, is also important.

Step 11: The Flowering Stage   

This can be the most exciting stage for growers, when buds begin appearing, hinting at the eventual harvest. The flowering stage lasts for about eight weeks. In the wild, plants enter the flowering stage as they prepare for winter, producing offspring before winter sets in. Within indoor grows, plants can be artificially sent into the flowering stage by placing them in darkness for 12 hours each day. By around  the third week of this process, small buds will appear, then in week four to eight these buds will grow more robust.  In the flowering stage, fertilization should be tweaked. Levels of nitrogen must be leveled off, while increasing amounts of phosphorus and maintaining potassium at the same level. From week eight onwards, a flush of pH balanced water can be administered instead of nutrients.

Step 12: When to Harvest Your Weed   

Deciding when to harvest your crop will depend on what kind of experience you are ultimately after in the finished product. As with all gardening considerations, much will depend on the strain. Generally speaking, sativas take longer to mature than indicas.

There are a few telltale signs that indicate the right time to harvest. When the stigmata – the hairy strands that grow off of buds – begin to change colors, this is when close examination of the trichomes should begin. When trichomes turn from transparent to opaque, and resemble a dusting of white sugar on the buds, it is time to harvest. 

Later harvests, when trichomes turn from opaque to amber in color, means that THC is being converted to a compound called cannabinol, or CBN. CBN has been found to reduce insomnia, inflammation and pain, without providing any psychoactive effects. 


Growing pot doesn’t have to be as scary as it seems. Like other forms of life, cannabis plants thrive with a little tender loving care – and the right space, equipment, fertilizers, and so on. 

There are many ways for beginners to ease into growing marijuana, as long as a little research and planning is done beforehand. The results can be an effective product, and a fun experience along the way.