How to grow weed indoors
Growing weed indoors is great because you can grow it any time of year and you’ll have complete control over the plant and what you put into it. Live in an apartment or a small house? Don’t worry, you can grow weed practically anywhere, even if you don’t have a backyard or a lot of extra space.
Benefits of growing weed indoors
Although it’s more resource-intensive than growing outdoors and you will likely have to spend more money on utilities to power equipment, you can control every aspect of your grow environment and what you put in your plant, allowing you to dial in your setup to grow some primo weed.
Unlike outdoor growing, you aren’t tied to the sun and the seasons. You will be providing the entire environment the plants need to grow, including the grow medium—soil, rockwool, etc.—and regulating the amount of water and nutrients they receive, as well as controlling temperature, humidity, and more for them.
You can let your plants get as big as you want, and can control when they flower and when you harvest, and you can start another batch right away or whenever you want. You can grow any time of year, even straight through winter or summer, and you’ll get consistent crops each time.
Privacy and security
Even in legal states, you may want to conceal your crop from judgmental neighbors and definitely from potential thieves. Growing indoors allows you to grow discreetly behind a locked door.
How to set up an indoor grow room
Below is a list of things to consider and equipment you will need to purchase to get started growing marijuana indoors.
You’ll need a dedicated space for your marijuana plants—you won’t be able to move them around. Ideally, the space is next to a window so you can vent air from the grow space outside. Growing weed plants smell! Especially when flowering kicks in, you’ll want to redirect air so your house doesn’t reek of weed.
A lot of people these days buy grow tents for their weed, but they aren’t necessary. You can grow in a closet, tent, cabinet, spare room, or a corner in an unfinished basement. Just keep in mind that you’ll need to tailor your equipment (and plants) to fit the space.
It’s a good idea to start small—the smaller the grow, the less expensive it is to set up. Newbie mistakes will be less costly if you only have a handful of plants. Additionally, most state laws only allow for growing six plants, but some allow up to 12.
When designing your space, you’ll need to take into account room for your plants, as well as space for lights, fans, ducting, and other equipment. You’ll also need space to work on the plants. Cannabis plants can double in size in the early stages of flowering, so make sure you have adequate head space!
Every space is different and there will be a learning curve to growing in yours.
Cannabis, like all plants, prefers certain environmental conditions in order to thrive. Temperature, humidity, light intensity, and airflow are all factors that will need to be monitored and regulated in order to keep cannabis healthy through its different phases.
Although you’ll be controlling the climate inside the grow space, climate outside the grow space will affect your plants. If the environment outside your grow space is very warm or humid, you’ll have issues controlling your grow space. Choose a cool, dry area with ready access to fresh air from outside.
If you’re growing in a cold, wet basement, you might have to run a dehumidifier or heater to stabilize the environment. Conversely, if your space is too hot, you might need to add extra fans or an AC to cool the plants down.
One trick to avoid hot temps is to have the grow lights on during the evening, when it’s cooler outside, and leave the lights off during the day when it’s hot. This may help bring down the temps, but you’ll only be able to work on the plants at nighttime when the lights are on.
Weed plants need different amounts of light during their vegetative and flowering stages. You don’t have to worry about this in an outdoor setting—the sun and the season dictate this—but when growing indoors, you will be controlling it.
Plants need 18 hours of light a day when in the vegetative stage and 12 hours a day when flowering. The reduction in light from 18 to 12 hours a day is what triggers the flowering cycle—when weed plants start to grow buds.
Because the amount of light a plant receives is so important, you’ll need to make your indoor grow space light-tight. Light leaks during dark periods will confuse your plants and can cause them to produce male flowers or revert to a different stage.
Different lights produce different colors of light. Here’s a brief rundown of the most popular types of cannabis grow lights used for indoor growing.
HID (high-intensity discharge) lights are the industry standard, widely used for their combination of output, efficiency, and value. They cost a bit more than incandescent or fluorescent fixtures, but produce far more light per unit of electricity used. Conversely, they are not as efficient as LED lighting, but they cost much less.
The two main types of HID lamp used for growing are:
- Metal halide (MH) produces light that is blueish-white and is generally used during vegetative growth.
- High pressure sodium (HPS) produces light that is more on the red-orange end of the spectrum and is used during the flowering stage.
In addition to bulbs, HID lighting setups require a ballast and hood/reflector for each light. Some ballasts are designed for use with either MH or HPS lamps, while many newer designs will run both.
If you can’t afford both MH and HPS bulbs, start with HPS as they deliver more light per watt. Magnetic ballasts are cheaper than digital ballasts, but run hotter, are less efficient, and harder on your bulbs. Digital ballasts are generally a better option, but are more expensive. Beware of cheap digital ballasts, as they are often not well shielded and can create electromagnetic interference that will affect radio and WiFi signals.
Unless you’re growing in a large, open space with a lot of ventilation, you’ll need air-cooled reflector hoods to mount your lamps in, as HID bulbs produce a lot of heat. This requires ducting and exhaust fans, which will increase your initial cost but make controlling temperature in your grow room much easier.
Fluorescent grow lights
Fluorescent light fixtures, particularly those using high-output T5 bulbs, are quite popular with small-scale cannabis growers because:
- They tend to be cheaper to set up, as reflector, ballast, and bulbs are included in a single package.
- They don’t require a cooling system since they don’t generate nearly the amount of heat that HID setups do.
The main drawback is fluorescent lights are less efficient, generating about 20-30% less light per watt of electricity used; space is another concern, as it would require approximately 19 four-foot long T5 bulbs to equal the output of a single 600 watt HPS bulb.
LED grow lights
Light emitting diode (LED) technology has been around for a while, and they are getting more efficient all the time. The main drawback to LED grow lights is their cost: well-designed fixtures can cost 10 times what a comparable HID setup would.
But the benefits are great: LEDs last much longer, use far less electricity, create less heat, and the best designs generate a fuller spectrum of light, which can get bigger yields and better quality.
Check out our buying guide on indoor lights for more info.
Plants need fresh air to thrive and carbon dioxide (CO2) is essential to the process of photosynthesis. This means you will need a steady stream of air flowing through your grow room, which will allow you to move hot air out of the space and bring cool air in.
This is easily achieved by placing an exhaust fan near the top of the space to suck out warm air—warm air rises—and adding a port or passive fan on the opposite side of the space near the floor to bring in cool air. A complete air exchange throughout the entire grow space should occur once every minute or so.
Without proper airflow, a grow space can experience rapid changes in humidity or develop pockets of CO2 depletion, neither of which are good for plant growth. CO2 depletion can lead to nutrient lockout, and areas of high humidity are prone to pest infestation, mold, or mildew.
It’s also a good idea to have oscillating fans to provide a constant breeze in your grow room as it will strengthen your plants’ stems, making them stronger and healthier.
Setting up fans
For small spaces or tents, clip-on fans can be attached to structures like walls, corners, or support beams. For larger grow rooms, use medium-sized oscillating fans or big floor models.
Fans should be positioned to provide direct, even airflow throughout the garden. This typically involves using multiple fans that work together or fans that have oscillation capabilities.
There should be a comfortable airflow both above and below the canopy, and fans shouldn’t blow air directly onto plants—this can cause wind burn, which makes leaves recede into a claw-like deformation.
Dehumidifiers and ACs
If your space is too humid, you may need to invest in a dehumidifier—also known as “dehueys.” However, keep in mind that while dehueys will reduce humidity, they typically increase temperature—you may need more fans or an AC when adding a dehumidifier.
Getting the right climate for your plants can be a delicate balance involving multiple pieces of equipment and also lots of electricity. This is part of what makes growing weed indoors more expensive than growing outdoors.
Fans are a must in a grow space to move air around, so buy some of those before an AC unit. If you find that fans aren’t bringing down the temperature enough, then you may want to invest in an AC.
You will definitely want to invest in a timer for your lights. Because the amount of light a plant receives dictates its vegetative or flowering stage, it’s important to give it a consistent amount of light every day, and that’s done with a timer. It’s a good idea to check your timer at least once a week to make sure it’s working properly.
You can also use a timer for your fans, but a thermostat is better—you can set it to a specific temperature, and the fans will turn on when it’s too hot and turn off when it’s too cold.
Most dehumidifiers and ACs have built-in thermostats, but if they don’t, you’ll want to buy an external one.
For growers who have a little extra money to spend and want full control over their indoor garden, environmental controllers will allow you to automate the process. These devices are essential for if you’re away from the garden for a long period of time.
You can connect a controller to fans, dehumidifiers, humidifiers, heaters, or air conditioners, and set thresholds whereby each device will power on and off based on your ideal environmental settings. Some units run autonomously, making changes based on set parameters, while others allow you to control each element via an app on a phone, tablet, or computer.
Regulating temperature and humidity in your indoor grow space
You’ll need to ensure that temperatures remain within a comfortable range for your plants, between 70-85°F when lights are on and between 58-70°F when off. Some varieties of cannabis—generally indicas—prefer the colder side of the range, while others—typically sativas—are more tolerant of high temperatures.
For the most part, weed prefers these temps at each growth stage for optimal health:
70% relative humidity
The two factors you need to control to dial in the environment are temperature and humidity.
Inevitably, there will be fluctuations of temperature and humidity in your cannabis garden. These fluctuations can occur both throughout a grow space as well as within pockets inside a given room. They can also occur at different points within a given day or throughout a season as conditions change in the environment outside your grow space.
It can be tricky getting the right balance of temperature and humidity because they affect each other—turning up your dehumidifier will lower the humidity of your grow space, but it will also increase the temperature of the area. This in turn may require you to turn on an AC unit—everything’s connected!
Tools to measure temperature and humidity
Equip yourself with these cheap and easy-to-use tools to take measurements in your indoor cannabis setup:
- Thermometer: A basic one will allow you to measure how warm or cool the environment is inside your garden.
- Hygrometer: This measures humidity, or more specifically, water vapor content in the air.
- Infrared thermometer, or IR thermometer (optional): IR thermometers use a detection device called a thermopile to measure surface temperatures. Although not necessary, these are helpful in finding out leaf temperatures, which will give you an extra layer of knowledge on how to properly regulate environmental conditions.
Controlling temperature in your indoor grow room or cannabis garden can be achieved by manipulating these factors:
- Lights: Different grow lights will give off different heat signatures. Hot lights such MH, HPS, and fluorescents produce much more heat than LEDs. Also, lights can be raised or lowered to change temperature at the canopy level.
- Airflow: You can remove warm air (up high) out of the garden and bring in fresh cool air (down low) with fans and ducting. Fans can also help exchange air throughout your canopy, cooling leaves in the process.
- ACs: You may need to bring in an air conditioner to rapidly cool the overall temperature of your grow space if it’s too hot and fans aren’t enough.
- Heaters: Some gardens may require warm air, especially during times when lights are off and not generating heat.
Humidity is the amount of water vapor in the air. Here are some ways to control it in your marijuana grow room:
- Dehumidifiers: Dehueys remove moisture from the air but also increase temperature.
- Airflow: As with regulating temperature, regulating airflow will allow you to move moisture in and out of your grow space and control humidity—simply opening up a space, i.e., opening the door to your grow room or tent, can bring down humidity.
- Humidifiers: A humidifier can add water vapor to a grow space and increases moisture levels if it’s too dry.
- Water: In the absence of a humidifier, you can mist plants with a spray bottle to create extra moisture.
Soil and other media for growing weed indoors
There are many different media to choose from, including good ol’ fashioned pots full of soil, rockwool cubes, a hydroponic tray, and more.
Soil is the most traditional medium for growing marijuana indoors, as well as the most forgiving, making it a good choice for first-time growers. Any high-quality potting soil will work, as long as it doesn’t contain artificial extended release fertilizer—like Miracle Gro—which is unsuitable for growing good cannabis.
Good soil for cannabis relies on a healthy population of mycorrhizae and soil bacteria to facilitate the conversion of organic matter into nutrients that a plant can use. Alternately, you can use a regular soil mix and then supplement your plants with liquid nutrients.
Finding the right soil for cannabis
For most first-time gardeners, we recommend buying a quality potting soil that will provide your plants with enough nutrients to get them through most of their growth cycle without having to add many amendments or liquid nutrients. This pre-fertilized soil—often referred to as “super-soil”—that can grow cannabis plants from start to finish without any added nutrients if used correctly.
You can make this yourself by combining worm castings, bat guano, and other components with a good soil and letting it sit for a few weeks, or it can be purchased pre-made from a local nursery or grow shop.
While shopping for soil, you might be overwhelmed by the options available at your local garden store. The soil type is the basic structure of your soil. From there, look at nutrients, microorganisms, and other amendments that improve the soil. Your choices will be flooded with words like:
- Worm castings
- Bat guano
- Peat moss
- Fish meal
- Bone meal
- Glacier rock dust
- Plant food
These are just some examples of amendments commonly used in different types of soils. Heavily amended soils will have long lists that break down all organic nutrients they contain. Some companies create soils that offer a great structure with base nutrients, but allow you to fill in the gaps as you desire.
What type of container you use will depend on the grow medium, the system, and the size of your plants.
Inexpensive options include standard plastic pots or cloth bags, while some growers choose to spend more on “smart pots” or “air pots”—containers designed to enhance airflow to the plant’s root zone.
What size pot do I need?
Many growers will start plants in a one-gallon pot and then transplant up to a bigger pot as plants get bigger. A lot of growers will transplant once, from a one-gallon to a five-gallon pot, and harvest from there. If your plants get bigger, they may need a seven- or ten-gallon pot.
What to look for in a pot
Your cannabis wants a safe, healthy place for root development. Without healthy roots, your cannabis will never thrive. Roots are in charge of water retention, nutrient absorption, anchoring the plant, and they also facilitate vegetative growth.
Drainage is key, as cannabis plants can get waterlogged and develop root rot. If you repurpose containers, be sure they have holes in the bottoms and set them in trays.
For a root system to develop and thrive, they will need the following:
- Drainage: Water retention is paramount for healthy plants—without it, your cannabis will wither and die. But too much water will waterlog your plant and lead to root rot, killing roots.
- Oxygen: Plant roots require oxygen to function properly. Choose a container that facilitates enough oxygen for root development without overexposing them to the elements—containers do this though various styles of perforation.
- Nutrients: Roots require optimal conditions for nutrient absorption to occur. This includes pH balance, optimal temperatures, and nutrient availability.
- Space: Roots need plenty of space to branch out. A container that is too small will cause it to become rootbound and choke the plant.
Traditional plastic containers
Standard plastic containers are a popular option for growers operating on a budget. These pots are inexpensive and provide the essentials for your plants.
- Low overhead costs
- Solid drainage (plus it’s easy to add more holes)
- Transplanting is easy and inexpensive
- Can’t protect root systems from temperature fluctuations as well
- Lack of durability which can cause cracks and structural damage over time
- May have airflow issues depending on the grow medium
These are quickly becoming the standard. Roots in fabric pots grow to the outer edges and attempt to bypass the porous fabric wall but are cut back, allowing new growth to occur. This process, called “air pruning,” results in a denser root composition which promotes healthy growth and development.
- Promotes dense, healthy root systems
- Increased airflow to roots
- Excellent drainage
- Require more attention and maintenance because they dry out quickly. Note: You can use larger pots to help slow drying.
- Flimsy structure can make plant support challenging
Terra cotta pots offer a unique set of benefits to growers in hot climates.
- Absorb moisture and retain lower temperatures during hot days
- Heavy weight helps to anchor larger plants
- Less than optimal drainage; drilling holes into clay pots is possible but requires special tools and is labor-intensive
- Heavy weight makes it difficult to transport plants
Caring for your indoor cannabis plants
When starting with clones or seedlings, you’ll want to check your plants every day because they’re delicate and sensitive to environmental conditions. You may need to adjust temperature and humidity levels in your indoor grow space at first to hit the sweet spot for your plants.
As your indoor weed plants grow, they’ll need less attention, but you’ll still need to check up on them every 2-3 days.
Watering and nutrients
When growing weed indoors, you’ll likely have to add nutrients to your plants. You won’t need to add nutrients every time you water, but get on a schedule where you water every other time, or two on, one off.
Before watering, check the pH of your water and add pH Up or Down if needed.
If using nutrients, estimate how much water you’ll need for all of your weed plants so you can measure out and mix in the appropriate amount of nutrients.
Remember, a common mistake newbie growers make is to overwater plants.
Check out our Guide on nutrients for more info.
Check for pests, mold, or nutrient deficiencies
You’ll also want to take this time to check over your weed plants for pests, mold, or nutrient 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. Also, check the soil for pests.
Make sure all equipment is on, no breakers have flipped, and everything is running smoothly. Check lights, timers, fans, dehueys, ACs, and anything else that plugs into the wall or has a battery.
Think of all the equipment in your grow space as organs in the body—if one fails, the others will have to work a lot harder for a bit, and then will fail in a matter of time.
Daily maintenance checklist for your indoor marijuana grow
- Water plants
- Check pH of water
- Measure and mix nutrients
- Check plants and soil for pests, mold, nutrient deficiencies
- Prune/remove dead leaves on plants if needed
- Determine if plants need topping
- Make sure plants are spaced properly and not shading each other out
- Adjust level of lights if leaf tips are getting burned
- Check temperature and humidity in grow space
- Check equipment is running properly, i.e., lights, timers, fans, dehueys, etc.
Indoor marijuana grow timeline
The growth stages of marijuana can be broken down into four primary stages from seed to harvest:
- Germination (3-10 days)
- Seedling (2-3 weeks)
- Vegetative (3-16 weeks)
- Flowering (8-11 weeks)
Generally speaking, it takes anywhere from 10-32 weeks, or about 3-8 months, to smoke what you’ve grown. (It’ll be quicker if you start with a clone or an autoflower seed.)
That’s a big variance, but it really depends on how big you want your plants and how often you want to harvest—you can have multiple harvests of smaller plants, or less harvests of bigger plants.
For example, it takes less time to grow 3′ weed plants than 5′ plants; in the span of a year, you can maybe grow four harvests of 3′ plants, or two harvests of 5′ plants.
You’ll likely yield about the same amount of weed in both cases, but more harvests mean you’ll have fresh weed to smoke more often and have more opportunities to grow different strains. But more harvests also means more work in cleaning up the space between harvests, trimming, etc.
The biggest variability in how long a marijuana plant takes to grow will happen in the vegetative stage—after the seedling phase and before flower.
The flowering stage will always take about eight weeks—some strains take seven, some nine, some even more, it depends on the strain.
So when growing weed indoors, you can control the size of your plants by flipping them into flower whenever you think they’re big enough in the vegetative stage.
Odor control in your indoor marijuana grow
As much fun as growing marijuana indoors is, having a home that perpetually smells like fresh weed can be a serious inconvenience, if not to you than possibly your neighbors. Although weed odor from a small indoor grow in a closet is much easier to manage than a large grow with several flowering plants, both can produce pesky odors that will permeate an entire home if left unattended.
Plants in the vegetative stage maintain a low odor as they haven’t begun to produce terpenes, the plant’s aromatic compounds. As weed plants transition into the flowering phase, trichomes will start to develop and produce terpenes, causing them to smell more.
Here are some ways to mitigate odor when growing weed indoors.
Check temperature and humidity levels
The first step in odor control is making sure temperature and humidity are under control in your grow space—high temperature and humidity will perpetuate odors.
As your plants get bigger and especially when they start flowering, they’ll start to smell more. Outfitting your grow with a dehuey or AC can help bring odor down.
Make sure air is circulating through your garden
Proper air circulation will help maintain temperature and humidity, and also bring down odor. Ideally, air needs to move through a garden every few minutes, and you should create a vent to the outside. Oscillating fans, and intake and exhaust fans can move air through your garden quickly, taking odors out with them.
Odor absorbing gels may help
Odor becomes much more difficult to manage in the final six weeks of a marijuana plant’s life, when trichomes and terpene production ramps up. You can also get odor-absorbing gels, which replace weed smells with other scents. Keep in mind that odor gels don’t eliminate odors, but simply mask them.
Activated carbon filters
These come in different shapes and sizes and are a great way to get rid of odor in an indoor weed grow. Also known as “carbon scrubbers” for their ability to get contaminants out of the air, these employ activated and highly ionized carbon to attract particulates responsible for carrying odor, such as dust, hair, mold spores, and volatile organic compounds, and traps them in a filter.
Carbon filters usually work best when positioned at the highest point in your grow space, where the most heat accumulates.
Patrick Bennett and Trevor Hennings contributed to this article.
Growing weed indoors is a great option for new homegrowers. Learn everything you need to know about growing weed indoors, including how to set up your grow room and climate control.
Cannabis Micro Growing: Growing Great Weed in Tiny Spaces
Worried you don’t have the space to grow great weed? Well, don’t! With micro growing, you can grow superb bud in the smallest of spaces.
The new trend of micro growing weed is challenging the norms of how much space it takes to grow great cannabis at home.
Thanks to new and improved grow gear (especially grow lights) and an increase in knowledge concerning the cannabis plant, micro growers are able to churn out great harvests in extremely small spaces.
In this article, we’ll walk you through everything you need to know about micro growing, and set you up to grow great weed in (almost) any space.
Understanding the Basics of Micro Growing
Micro growing is regular indoor growing, but on a smaller scale. It’s all about producing top-shelf bud with all the flavour, aroma, and potency you want, but in confined spaces (such as small DIY tents, cupboards, bar fridges, or even hulled desktop computer towers). Alternatively, some growers opt to buy ready-made stealth grow boxes.
The minimum amount of space you’ll need to grow weed in a micro setup is 35 × 35 × 75cm. To accommodate the lack of space in a micro grow, you’ll have to make minor adjustments to your lighting and ventilation, the strains you choose to grow, your medium, and your watering/feeding schedule.
Using the Right Amount of Soil
Micro growing is usually done using soil, as setting up a soilless or hydro system in a space as small as a mini-fridge can be very difficult. So, to accommodate the lack of space that qualifies a micro grow, you’ll want to use less soil to prevent your plants from outgrowing their small room or tent.
The root system is a crucial part of the plant, and its size has a great influence on how tall the plant will grow. Most plants tend to occupy the same amount of space below the ground as they do above. In a micro grow, we can use this correlation between the size of the root system (thus, the amount of medium) and plant size to control the growth of our cannabis plants and match it to our spatial limitations.
Below you’ll see how different pot sizes will impact the height of your cannabis plants:
Note that these figures are just estimates, and the exact size of your cannabis plants will vary depending on their genetics. Also, keep in mind that plants grown in small containers will need to be fed and watered more regularly than plants grown in larger containers with access to more soil.
For micro growing, we generally recommend sticking to 3l pots. However, we’ve seen some growers working with slightly larger spaces use up to 9l pots. How big or small you choose to go with your pots is up to you; just keep in mind that using bigger pots will likely restrict the number of plants you can grow (but more plants won’t necessarily translate to a bigger micro grow yield).
Finding the Right Grow Light
First and foremost, you’ll want to turn to LEDs for micro grows. HPS and HPI lights simply aren’t suited to these small grows as they produce far too much heat.
For the best results, we recommend using LED panels. A 15W panel is capable of producing op to 3000 lumens while producing almost no heat and taking up virtually no space (the panel measures just 130 × 110mm).
Alternatively, we recommend using any small 60W LED panel for your micro grow. Depending on just how small of a space you’re growing in, you’ll likely never need to keep this panel running at 100% capacity. We recommend keeping it at 25–50% to help control your plant’s stretch during veg, then turning it up to 50–75% during bloom, depending on the plant’s stretch. You can also control the panel’s light schedule using a controller, which is app-operated.
Properly Placing Your Grow Light
One common question micro growers face is this; where do I place my grow lights?
Traditional indoor grow setups place the main grow light directly above the canopy. But, since micro growers are often working with extremely small spaces, this setup might not always be the best option.
In small vertical spaces (like a grow box, small cupboard or furniture piece, or computer tower), you’ll usually be better off placing your main grow lights along one or multiple sides of your plant. This will allow you to grow a bigger canopy, improve light penetration through the canopy, and prevent plants from stretching towards the top of your grow space.
For even more control, you may want to consider building two separate grow boxes; one for veg and another for bloom. In the veg box, you may be able to get away with placing your grow light right above your plant, as light penetration isn’t as much of an issue during veg as it is during flowering. Remember to keep in mind the speed at which your plants grow, and try to find strains that grow at a speed that suits the size of your space.
If you do opt to install your veg light above your plants, remember to keep it at the right distance and intensity. If your grow light is too close or too strong, plants are likely to develop very short internodes and might show signs of light stress. If, on the other hand, your light is too far or too weak for your plants, they’re going to stretch and develop long internodes.
In your bloom box, however, we recommend placing your grow light along the sides of your plants. This will provide the best light penetration and allow you to grow a longer vertical canopy of buds. We also recommend using a vertical net to keep your plants centered. You can also use this net to train your plants gently and control their growth as you see fit, given your space.
How to Manage Ventilation and Smell in a Micro Cannabis Grow
While it might seem like a trivial detail, properly ventilating your cannabis micro grow is a must. When working with such a small space, air can quickly become stagnant and start creating a lot of problems for your plants. This is because plants consume the CO₂ in their environment for photosynthesis. When growing in such small spaces, your plants have very limited access to fresh, CO₂-rich air, making proper ventilation a must for healthy plants.
Luckily, ventilating a cannabis micro grow space is easy.
If you decide to build your own micro grow setup, all you’ll need to keep your space ventilated is a small outtake fan, like this 24V Brushless Centrifugal Blower. While it might not look like much, this tiny fan will do a perfect job at removing old, stagnant air from your grow space. For the best results, we recommend installing it directly above your plants.
If you’ve got enough space, you may even want to consider keeping a small hand-held fan inside your space to keep air circulating properly around your plants.
For even better ventilation and air circulation, we recommend installing a small intake fan at the bottom of your micro grow setup. A high-speed cooling fan, for example, will let a constant influx of fresh air into your micro grow space.
Because micro grows usually only allow you the space to grow one small weed plant (or two), you shouldn’t need to use carbon filters to manage the smell of your operation. However, if you want to be extra safe, installing a carbon filter to the outtake fan we mentioned above is simple. The filter needs to be installed in front of your outtake fan, and therefore may rob you of some space inside your mini grow room/box.
How to Water Cannabis Plants in a Micro Grow
Watering your cannabis plants in a micro indoor setup can be tricky due to the lack of space. If you’re building your own micro setup, take this into consideration and try to leave enough space around the base of your plants so you can water them comfortably. Remember that water splashing up onto the foliage and buds of your plants can cause fungal issues, so you’ll want to avoid it at all costs.
If you’re growing in a truly tiny space—one where you can’t walk around or get a good position over your plants—make sure you can remove your plants for watering so you don’t end up making a mess of your space.
Given the small scale of a micro grow, we generally don’t believe they warrant the installation of any automatic watering systems. Just have the patience to manually water your plants using a small watering can or bottle.
How to Use Growing Techniques in a Cannabis Micro Grow Setup
Micro grows typically call for smaller, bushier plants. In order to achieve this kind of structure and produce decent harvests in such small spaces, you’ll want to employ some growing techniques like LST, HST or ScrOG, and Defoliation. Below, we’ll share some basic tips on how to adapt these techniques to a micro grow setup.
LST is easily one of our favourite grow techniques, and can come in super handy when growing in small spaces. The only way your LST technique might vary when micro growing is in how you direct your plant’s growth. Remember, the goal of LST is to open up your plant and improve light penetration. Think about how you’ll achieve that given the lighting in your micro grow room.
HST (Topping, Super Cropping, FIM, etc.)
High-stress techniques may be a little trickier to apply to a micro grow. Topping or fimming, for example, create multiple dominant colas, which may not be ideal in small, narrow vertical indoor gardens.
If you’re growing in a short yet wide space (like a shelf, for example), you may want to use super cropping or fimming early on to create a short canopy packed with thick colas. In fact, super cropping may come in handy in either case, as it strengthens your plant in time for bloom and, like LST, can direct growth in the right direction to make better use of your lights.
Screen of green is another of our favourite training techniques, and you’ll be glad to know you can take advantage of it even in small micro cannabis gardens. If you’re working with a narrow vertical space with lateral lights, for example, using a vertical screen can be one of the best ways to create a big canopy that receives a ton of light.
In a short, horizontal micro grow cabinet, on the other hand, you can use ScrOG as you would in a regular indoor garden to create a thick, even canopy that, come harvest time, will be loaded with sticky buds.
Defoliation is essential to micro growing. In a narrow, vertical grow room with lateral lights, defoliation will help you clear unnecessary foliage and ensure all parts of your plant get enough light to develop big, thick buds.
When to Switch Your Micro Grow Room to Bloom
In general, we recommend you flip your vegetative cannabis plants to bloom once they’ve grown to half of the height of your micro grow box. This will ensure they’ve still got enough space to accommodate their pre-bloom stretch without growing too close to the top of your box/room.
Remember that the rate at which your plants grow is directly related to the amount of light they receive. More light will result in shorter internodes, while plants grown with less light will stretch, resulting in larger spaces between each node. You may need to play around with the lighting in your micro grow room to find the sweet spot for each of your strains.
Micro Growing Cannabis: Expect Realistic Results
As with any cannabis grow, it’s important to set yourself some realistic expectations regarding the size and quality of your harvest, as well as the amount of time it’ll take you to get from seed to harvest.
In general, growing in a small 35 × 35 × 75cm space using a rough average of 30W of light throughout your entire grow, you can expect to harvest between 25 and 45g, depending on the strain, your feeding routine, training techniques, and skill. You’ll usually be able to go from seed to harvest within 3–4 months, depending (obviously) on your light cycle and the genetics of your plants.
Finally, the cost of setting up your micro grow box/room will vary greatly. If you choose to build your own micro grow space, you may be able to do so relatively cheaply (keep in mind that your LED panel will easily be the biggest upfront cost).
Choosing A Suitable Strain
When it comes to micro growing, choosing the right strain is very important due to the limited space available. One of the things to watch out for is the height of your cannabis strain. Sativas grow higher and more slender than indicas, which tend to be short and bushy.
Furthermore, during the flowering phase sativas undergo a 200-300% increase in height, while Indicas increase only by 50-100%, which shows that indicas are more compatible with micro growing.
Another reasonable option would be autoflowering strains. No matter what the conditions, autoflowering strains stay small due to their genetics (a great many of them even smaller than indicas) and aren’t dependent on the light regime, which means they will have a shorter harvest time.
3 Great Strains for Micro Growing
Of course, some genetics are more suited to micro growing than others, and the following three are prime examples of quality picks. You’ll notice these strains all have something in common: they’re autoflowering.
Royal Dwarf truly is a miniature cannabis specimen that can remain at tiny sizes of 40cm tall when trained in the ways mentioned above. This plant was bred for one reason and one reason only: stealth. Growers can easily cultivate multiple Royal Dwarf plants in their home without a single suspicion being raised. She can easily be grown within modified kitchen cupboards, wardrobes, boxes, and computer towers. Small LED lights can also be used within these tiny spaces to avoid giving off too much heat. Royal Dwarf is essentially the autoflowering version of the legendary Skunk, and was made using a Skunk strain along with a specific ruderalis cultivar. She offers stimulating but subtle sativa highs fuelled by THC quantities of 13%. She can therefore be smoked all day long whilst allowing the user to stay on top of their game and not get too high. Her small yet compact flowers offer sweet and citrus tastes.
Royal Dwarf will be ready to harvest a mere 8–9 weeks after seeds have been germinated. Plants grown indoors will provide yields of up to 200g/m² and won’t exceed 70cm in height. Plants grown outdoors within garden beds or guerrilla grow spots will produce harvests of 30–80g/plant and reach heights of between 50–90cm.
Think you haven't got the space to grow weed? Think again. With our guide on micro growing, you can grow top-shelf bud at home in even the tiniest of spaces.