How to Grow Cannabis
Indoor gardening is great for growing weeds because they can be grown at any time of the year. You also have full control over what you plant and how it grows. Do you live in an apartment or a small home? You don’t need a large yard or much extra space to grow marijuana.
Indoor marijuana cultivation has many benefits.
While it is more difficult to grow outdoors, you may need to spend more on utilities to power equipment and grow your plants, you have complete control over your environment and the things you put in your plant. This allows you to create the perfect setup for primo weed.
Unlike outdoor gardening, you are not tied to the weather or the seasons. You will provide the environment for plants to thrive, including the soil, Rockwool and other grow mediums.
You can allow your plants to grow as large as you like. You can also control when and how often they flower. Also, you can always start another batch of plants right away. You can grow at any time of the year, even in winter and summer. Each season will yield consistent crops.
Security and privacy
Even in legal states, you might want to hide your crop from neighbors and potential thieves. Indoor gardening allows you to grow discreetly behind closed doors.
How to set up an indoor growing room
Here’s a list of items to look at and equipment that you will need to grow marijuana indoors.
A dedicated area is required for marijuana plants. They won’t be mobile. The ideal space should be next to a window that allows you to vent the air from your grow space. The smell of weed plants growing! You’ll need to redirect the airflow so that your house doesn’t smell like weed, especially when flowering begins.
Many people buy grow tents these days, but they’re not necessary. A closet, tent, cabinet or spare room can all be used to grow your weed. Keep in mind that your equipment and plants will need to be adapted to the space.
It is a good idea not to grow too many plants. The smaller the plant, the more affordable it will be to set up. If you have only a few plants, mistakes made by newbies will be easier to avoid. Moreover, while most states allow you to grow six plants, some states allow you to grow up to 12 plants.
When designing your space, you will need to consider space for plants and space for fans, lights, and other equipment. It is also important to have enough space for your plants. In the beginning stages of flowering, cannabis plants can double in size, so ensure you have enough space for your head!
Every space is unique and you will need to learn how to grow in it.
Like all plants, cannabis needs certain conditions to thrive. To keep cannabis in its various phases healthy, it will need to be controlled and monitored for temperature, humidity, light intensity and airflow.
While you can control the climate in your grow space, the outside climate will impact the plants. You will have problems controlling the environment in your grow area if it is too hot or too humid. You should choose a dry, cool area that has easy access to fresh air.
To stabilize a damp or cold basement, you may need to use a heater or dehumidifier. If your space is too warm, you may need additional fans or an air conditioner to cool it down.
To avoid high temperatures, keep the grow lights on in the evening when it’s cooler and the lights off in the daytime when it’s hot. While this may reduce the temperature, you won’t be able to work with the plants until the lights go out at night.
Weed plants require different light levels during the vegetative and flowering phases. This is something you don’t need to worry about in outdoor settings, as the sun and season dictate it. But indoors, it will be your responsibility.
When in the vegetative stage, plants need 18 hours of sunlight per day and flowering plants require 12 hours. The flowering cycle is when weed plants begin to grow buds.
You must make sure your indoor space is well-lit. Your plants can be confused by light leakage during dark periods. This could cause them to either produce male flowers or revert back to their previous stage.
Different lights produce different light colors. Here is a quick overview of the most common types of indoor cannabis grow lights.
The industry standard for high-intensity discharge (HID) lights is HID. They are widely used because of their efficiency, output, and value. Although they are more expensive than fluorescent or incandescent fixtures, they produce more light for every unit of electricity. They are less efficient than LED lighting but cost less.
Two main types of HID lamps are used for growing:
- The metal halide (MH), is a light-producing substance that produces a blueish-white color and is used in vegetative growth.
- High Pressure Sodium (HPS) produces more light on the red-orange side of the spectrum. It is used during flowering.
For HID lighting, you will need a ballast and hood/reflector to power each bulb. While some ballasts can be used with HPS or MH lamps, others will work with both.
You can choose to start with HPS bulbs if you don’t have the budget for both MH or HPS bulbs. They provide more light per watt. While digital ballasts are more affordable than magnetic ballasts, they are hotter and less efficient than the latter. They also last longer and are harder to use. While digital ballasts are usually a better choice, they are also more expensive. Avoid cheap digital ballasts as they can cause electromagnetic interference which can affect WiFi and radio signals.
If you don’t have a lot of space to grow in, you will need an air-cooled reflector cover to place your HID bulbs. You will need to install ducting and exhaust fans. This will reduce your initial costs but also make it easier to control the temperature in your grow space.
Fluorescent grow lamps
Because of their high output T5 bulbs, fluorescent light fixtures are very popular among small-scale cannabis growers.
- Because they include reflector, ballast and bulbs in one package, they are usually cheaper to put together.
- They don’t need a cooling system because they don’t produce nearly as much heat as HID systems.
Fluorescent lights are less efficient than HPS bulbs, producing about 20-30% less light for every watt of electricity. Space is also a concern as they would need approximately 19 T5 bulbs that measure four feet in length to produce the same output as a 600-watt HPS bulb.
LED grow lights
LED technology is not new, but they are becoming more efficient every day. The downside to LED grows lights is the high cost. A well-designed fixture can be 10 times more expensive than a comparable HID setup.
The benefits of LEDs are many: They last longer, consume far less electricity and produce less heat. Furthermore, the best designs can generate a wider spectrum of light, leading to higher yields and better quality.
For more information, please see our indoor lighting buying guide.
Fresh air is vital for plants to thrive. CO2 (carbon dioxide) is also essential for photosynthesis. You will need to have a constant airflow through your grow space. This will allow you to move hot air out and let cool air in.
You can do this by placing an exhaust fan at the top of your space to draw out heat. Warm air rises. A port fan or passive fan is placed on the other side of the space, near the floor, to bring in cool air. Each minute should be enough to ensure that there is an air exchange in the entire space.
A grow space without proper airflow can suffer rapid changes in humidity and develop pockets of CO2 loss, both of which are not good for plant growth. High humidity can cause nutrient lockout and pest infestation.
You can also have oscillating fans in your grow area to give your plants a constant breeze. This will help strengthen your plants’ stems and make them healthier.
Clip-on fans are great for tents and small spaces. They can be attached to walls, corners, beams or other support structures. Medium-sized oscillating fans and large floor models are best for larger grow spaces.
Fans should be placed so that there is constant airflow throughout the garden. This can be done by using multiple fans or oscillation fans.
Fans should maintain a comfortable airflow above and below the canopy. This can cause windburn, which causes leaves to recede into a claw-like shape.
ACs and dehumidifiers
You may need a dehumidifier if your space is too dry. Also known as “dehueys”, dehueys can reduce humidity but also increase temperature. This means that you will need more fans or an air conditioner when installing a dehumidifier.
It can be difficult to achieve the perfect climate for your plants. This requires a lot of electricity and multiple pieces of equipment. This is why growing weed indoors can be more costly than outdoor gardening.
Fans are essential if you have a space that needs to circulate air. An AC unit may be better if fans don’t bring down enough temperatures.
A timer is a great investment for your lights. A timer is a great way to ensure that your plants get enough light each day. This will help them grow and bloom in the right stages. To make sure your timer is working correctly, it’s a good idea that you check it at least once per week.
A timer can be used for fans as well, but a thermostat works better. The thermostat can be set to a temperature and fans will turn on when it gets too hot or off when it gets too cold.
Many ACs and dehumidifiers come with thermostats built-in. But, if not, an external one will be required.
Environmental controllers are a great option for growers who have more money and want to control their indoor gardens. These controllers are crucial if you are away from your garden for an extended period.
A controller can be connected to fans, humidifiers and heaters. You can also set thresholds for each device to turn on or off depending on the environment. Some units can run independently and make changes based upon set parameters. Others allow you to control the elements via an app on your phone, tablet or computer.
Controlling the temperature and humidity of your indoor garden space
Temperatures should be maintained within a comfortable temperature range for your plants. This means that they must remain between 70-85degF during daylight hours and between 58-60degF at night. Certain strains of cannabis, such as indicas, prefer the cooler side of the temperature range. Others, like sativas, are more open to high temperatures.
These temperatures are the best for weed’s health.
- Seedlings/clones: 75-85degF; ~70% relative humidity
- Vegetative Growth: 70-85degF, 40-60% relative humidity
- Flowering: 65-80degF, 40-50% relative humidity
Temperature and humidity are the two main factors that you must control in order to dial in your environment.
There will always be temperature fluctuations in your cannabis garden. These fluctuations can happen both in a grow area and within a specific room. These fluctuations can occur at different times during a day or season depending on the environmental conditions outside your grow space.
It can be difficult to achieve the right temperature and humidity balance. A dehumidifier will reduce the humidity in your space but will also raise the temperature. You may need to turn on an AC unit as everything is connected.
Tools for measuring temperature and humidity
These tools are inexpensive and simple to use for measuring your indoor cannabis plant.
- Thermometer This basic thermometer will let you measure the temperature of your garden’s environment.
- The Hygrometer measures humidity or, more precisely, water vapor in the air.
- Infrared temperature thermometer or IR thermometer (optional). IR thermometers measure the surface temperatures using a device called a thermopile. These are not required, but they can be useful in determining leaf temperatures. This will allow you to gain additional knowledge about how to regulate environmental conditions.
Regulating the temperature
These factors can be used to control the temperature of your indoor cannabis garden or grow room.
- Grow Lights: Different grow light types will emit different heat signatures. The heat produced by hot lights like fluorescents, HPS and MH produces more heat than LEDs. To alter the temperature at the canopy level, lights can also be adjusted to increase or decrease.
- Airflow With fans and ducting, you can take warm air (up-high) from your garden and bring in cool air (down-low). Fans can be used to exchange the air in your canopy and cool the leaves.
- ACs If your space is too hot or the fans aren’t working, you may need an air conditioner to cool it quickly.
- Heaters Warm air is needed for some gardens, particularly during dark hours when the lights are not on and do not generate heat.
Humidity refers to the level of water vapor in the atmosphere. Here are some ways you can control humidity in your cannabis grow room.
- Heaters: Heaters remove moisture from the air and also raise temperature.
- Airflow Just like regulating temperature, controlling airflow allows you to move moisture into and out of your space. You can also control humidity by opening up a space (e.g., opening the doors to your tent or grow room) to bring down humidity.
- Humidifiers If the space is too dry, a humidifier will add water vapor.
- Water If you don’t have a humidifier, you may mist your plants with a spray can to add moisture.
For indoors growing of weeds, soil and other media
There are many media options available, including pots with soil and Rockwool cubes as well as a hydroponic tray.
The best medium to grow marijuana indoors is soil. It’s also the most reliable and forgiving. Any high-quality potting soil can be used as long as it does not contain Miracle-Gro or any other artificial extended-release fertilizer. This is because Miracle-Gro is not suitable for growing quality cannabis.
A healthy soil bacteria and mycorrhizae population is essential for good cannabis soil. This will allow the plant to convert organic matter into useful nutrients. Alternately you can mix regular soil with liquid nutrients to supplement your plants.
The right soil to grow cannabis
We recommend that first-time gardeners purchase a high quality potting soil. This will give your plants enough nutrients to last most of the growth cycle. Pre-fertilized soil, also known as “super-soil”, can be used to grow cannabis plants without the need for additional nutrients.
You can make it yourself by mixing worm castings and bat guano with good soil. Let it sit for several weeks before you buy it.
You might feel overwhelmed when shopping for soil at your local garden shop. The basic structure of your soil is known as the soil type. The soil type is the basic structure of your soil. Next, you can look at nutrients, microorganisms and other amendments that enhance the soil. You will find words such as:
- Worm castings
- Bat guano
- Peat moss
- Fish meal
- Bone meal
- Glacier rock dust
- Plant food
These are only a few examples of common amendments used in different soil types. Heavily amended soils can have lengthy lists that reduce all organic nutrients. Some soils are designed to provide a strong structure and allow you to add or subtract nutrients as needed.
The type of container that you choose will depend on what grow medium you use, how large your plants are, and the size of the system.
Some growers will choose not to buy cloth bags or standard plastic pots. Others may opt for “smart” or “air” pots, which are containers that increase airflow to the root zone.
What size pot should I use?
Many growers start their plants in a 1-gallon pot, and then move to a larger pot as the plants grow. Many growers will only transplant one time, usually from a one-gallon container to a five gallon pot and then harvest the plants. A seven- to ten-gallon pot may be required if your plants grow larger.
What should you look for when buying a pot
Cannabis needs a healthy, safe environment for root development. Your cannabis won’t thrive if it doesn’t have healthy roots. Roots are responsible for water retention, nutrient absorption and anchoring the plant. They also aid in vegetative growth.
It is important to drain your cannabis plants, because they can become waterlogged and get root-rot. Repurpose containers by making sure the bottoms are drilled and placing them in trays.
These are the essential elements for a root system that can develop and thrive:
- Drainage Water retention is essential for healthy cannabis plants. Without it, your cannabis will die and wither. Too much water can cause root rot and waterlogging, which will ultimately lead to the death of your cannabis plants.
- Oxygen: For plant roots to function properly, oxygen is essential. You should choose a container that allows for sufficient oxygen to root development, without exposing them too much to the elements. There are many styles of perforation.
- Nutrients Roots need optimal conditions to allow nutrient absorption. This includes optimal pH balance, optimal temperatures and nutrient availability.
- Space: Roots require plenty of room to grow. Too small containers can choke and rootbound the plants.
Traditional plastic containers
Standard plastic containers are a good option for growers on a tight budget. These pots are affordable and will provide all the necessary nutrients for your plants.
- Low overhead costs
- Solid drainage is a plus, and it’s easy for you to add more holes.
- Transplanting is simple and affordable.
- Root systems are not protected from temperature fluctuations.
- Inadequacy in durability can lead to cracks and structural damage.
- Airflow problems may occur depending on the growing medium.
These are rapidly becoming the norm. Fabric pots allow roots to grow outwards from the walls of the fabric. However, they are cut back to allow for new growth. Air pruning is a process that results in denser roots that encourage healthy growth and development.
- Promotes dense, healthy root systems
- Roots receive more airflow
- Excellent drainage
- They dry quickly and require more care. You may use larger pots to slow down drying.
- Plant support can be difficult if the structure is weak.
Terracotta pots provide a unique set of benefits for growers in hot climates.
- Absorb moisture to retain lower temperatures on hot days
- Heavyweight can anchor larger plants
- Poor drainage is possible; drilling holes in clay pots requires special tools and is labor-intensive.
- Plants can be difficult to transport due to their heavy weight.
Caring for your indoor cannabis plants
You should check your plants daily if you are starting with seedlings or clones. They are delicate and highly sensitive to changes in the environment. To find the perfect temperature and humidity for your plants, you may have to adjust the temperature and humidity in your indoor garden space.
Your indoor weed plants will require less attention as they grow, but you still need to inspect them every 2 days.
Watering and nutrition
You will likely need to provide nutrients for your plants when growing weed indoors. Although you don’t have to water your plants every day, you can set a schedule that allows you to water only once a week.
Check the pH of your water before watering. If necessary, add pH Up or down.
Calculate how much water your plants will need to grow nutrients so that you can mix the right amount.
Overwatering plant is a common mistake made by newbie growers.
For more information, see our Guide to Nutrients.
Verify for any signs of mold, pests, or nutritional deficiencies
This is also a good time to inspect your weed plants for any pests, mold or nutritional deficiencies.
Examine the tops and undersides of leaves for pests or discoloration–spider mites live on the underside of leaves–as well as stalks and branches. You should also check the soil for any pests.
Check that all equipment is turned on and that no breakers have flipped. Also, ensure everything runs smoothly. Make sure to check lights, timers and fans, as well as dehueys and ACs.
Consider all equipment in your grow area as organs. If one of them fails, the rest will need to work harder and eventually will give up.
Check your indoor marijuana plant’s daily maintenance schedule
- Water plants
- Check the pH of your water
- Mix nutrients and measure them
- Verify that soil and plants are free from pests, mold, and nutrient deficiencies
- If necessary, prune or remove dead leaves from plants
- Find out if your plants require topping
- Space plants so they don’t shade each other.
- If leaf tips get burned, adjust the level of light
- In your grow space, check the temperature and humidity
- Verify that equipment is working properly.
Indoor marijuana grows timeline
You can break down the growth stages of marijuana into four main stages, from seed to harvest.
- Germination (3-10 Days)
- Seedling (2-3 Weeks)
- Vegetative (3-16 weeks)
- Flowering (8-11 Weeks)
It takes about 3–8 months to smoke the cannabis you have grown. It will take longer if you start with an autoflower or clone.
This is a large variance. However, it all depends on how big your plants are and how often you harvest them. You can harvest multiple smaller plants or fewer larger plants.
It takes less time to grow 3′ weeds than 5′; you could possibly grow four harvests from 3′ plants in a year or two harvests from 5′ plants.
Both cases will likely produce the same amount of marijuana, but you’ll be able to get fresher weed more often and more chances to grow different strains. However, more harvests mean more work when it comes to trimming, pruning, and cleaning up after harvests.
The vegetative stage, which is after the seedling phase but before the flowering stage, has the greatest variability in the time it takes for a marijuana plant to grow.
Flowering will take approximately eight weeks. Some strains may take seven or nine weeks depending on their strain.
You can also control the size of your weed plants indoors by turning them into flowers when they reach the vegetative stage.
Odor control in your indoor marijuana grow
Growing marijuana indoors can be fun, but a home that smells like fresh marijuana can cause serious problems. While weed odor from an indoor grow is easier to control than one with many flowering plants, it can still permeate a home.
The vegetative stage of plants has a low odor because they haven’t yet begun to produce the plant’s aromatic compounds, terpenes. When weed plants enter the flowering stage, trichomes will develop and begin to produce terpenes. This makes them smell stronger.
These are some of the ways you can reduce odor from growing weed indoors.
Monitor the temperature and humidity.
First, make sure your grow space is under control for temperature and humidity. High humidity and temperature will only lead to more odors.
Your plants will smell stronger as they grow, especially when they begin flowering. A deputy, or AC, can be used to reduce odor in your plants.
Air must circulate through your garden.
Air circulation is essential to maintain temperature and humidity and reduce odor. Air should circulate through your garden at least once every 30 minutes. To achieve this, you will need to create a vent that leads outside. Oscillating fans and intake and exhaust fans are great for moving air quickly through your garden and taking out odors.
Odor absorbing gels may help
The final six weeks of a marijuana plants life make it more difficult to control odors. This is when trichomes are produced and terpene production increases. There are also odor-absorbing gels that can be purchased to replace the weed smells with another scent. Remember that odor gels do not eliminate odors but only mask them.
Activated carbon filters
They come in many sizes and shapes. This is a great way of getting rid of odors in indoor weed plants. These are also known as “carbon scrubbers” because they can remove contaminants from the air. They use activated and highly-ionized carbon to attract volatile organic compounds and particulates that cause odor.
Carbon filters work best when placed at the highest point of your growing space. This is where heat accumulates.