How To Grow Weeds From Seeds To Harvest Indoor

Want to grow weed indoors but need tips? With this step-by-step-guide we will learn you everything you need to now for a succesfull grow. Happy growing! 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.

How to Grow Weed Indoors
(15 Step Beginner Guide)

This is the Step-by-Step guide to How to Grow Weed Indoors for Beginners.

In this new guide you will learn:

  • Why & when grow indoors
  • The pros and cons
  • 10 steps in the preparation phase
  • 5 steps in the growth phase
  • Lots more

In short: if you are a beginner and you want learn how to grow weed indoors, this guide will get you started!

Let’s get started!

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  • Happy growing!
  • Why grow indoors?
  • Steps to growing indoors
  • Step 1. Choose your location
  • Step 2. Choose your grow tent
  • Step 3. Choose your lights
  • Step 4. Choose your ventilation
  • Step 5. Choose your air conditioning/heating units
  • Step 6. Choose your pots
  • Step 7. Pick the right tools
  • Step 8. Buy your seeds
  • Step 9. Purchase nutrients
  • Step 10. Pick your growing medium
  • Step 11. Germinate your seeds (3–10 days)
  • Step 12. Taking care of your seedlings (2–3 weeks)
  • Step 13. Caring during the vegetative stage (3-16 weeks)
  • Step 14. Treatment during the flowering stage (8-11 weeks)
  • Step 15. Harvest and dry your buds (1-3 weeks)

Why Grow Indoors?

One might imagine an expansive outdoor field or a greenhouse when they think about growing weed.

Doing it indoors instead can offer a variety of benefits — especially for beginners.

If you’re looking to keep a close eye on your plants and hoping for a controlled setup, this might be a suitable option for you!

A wonderful thing about growing weed is that this plant can survive, and even thrive, in numerous setups, whether outdoors or inside.

Choosing to move your project indoors offers advantages that are quite beneficial for beginner growers. There are also a fair amount of disadvantages you need to be aware of before proceeding.

Pros to Indoor Growing

  • Environmental control
  • Management of soil
  • Grow year-round
  • Discreet
  • High THC percentages
Environmental Control

Weed requires specific nutrients and conditions to grow successfully. Factors such as moisture and light control are essential throughout the process. Growing weed indoors offers you the chance to take greater care of your environment than you can outdoors.

Monitor your lighting needs with the help of lamps and tents. Temperature control is also easier, thanks to central units and individual stations like the use of fans. Furthermore, you’re able to water at your discretion without the fear of unknown weather conditions encroaching on your yield.

Since a plant’s needs differ from species to species, this enables you to monitor a variety of strains at once.

Management of Soil

Taking control of the soil outside, while possible, is much more complex than the manageable situation you have inside. Where outdoors you have, at times, unfavorable conditions to worry about, indoors you’re able to control your soil conditions.

Factors include how much water the soil receives and when that happens. On the flip side, you don’t have to worry about your soil drying up.

Grow Year-Round

This is a major bonus to indoor growing because it indicates you can harvest more than once per year. An outside harvest, unless you are opting for autoflowering plants, occurs just once a year and usually in the fall.

With your controllable indoor conditions, you’re able to grow a wider variety. It also provides more room to quickly recover from your mistakes (don’t worry, it happens) — it won’t require you waiting an entire year to adjust your methods accordingly.


With the help of ventilation systems with a carbon filter (this is indispensable!), growing indoors doesn’t have to permeate your entire home with a total skunk aroma. It allows you to be more discreet about your endeavors, instead of planting in your publicly-exposed yard or garden.

High THC Percentages

Rumor has it that growing indoors means better quality, once again, thanks to all that control you have.

By high quality here, we mean strong strains with a robust THC content. Are potent buds a deciding factor for you? Growing indoors will be your best bet.

Cons to Indoor Growing

  • Costly endeavor
  • Labor intensive
  • Lower yield
  • The legalities
Costly Endeavor

One of the biggest drawbacks to growing indoors are the resources required to pull it off. All of the environmental control factors aren’t free, after all.

From your setup to ongoing costs, you have to factor in supplies such as lights and electricity and water bills, to name a few. Ventilation setups aren’t cheap either but are also necessary.

It’s not essential to go high-end here, but the other side of that coin is going too cheap and risking an unsuccessful yield. As you’ll find out, it’s crucial you maintain each step of the growing process with quality and care.

Labor Intensive

Much of growing outdoors means leaving it up to nature. It’s risky, yes, but this also means less work on your part.

Those indoor environmental controls don’t just happen automatically — they require precise, dedicated labor and lots of it. From everyday upkeep to obsessing over the conditions in rough summer months, you’ll have to keep tabs on your plants daily.

Do you like to vacation frequently? This is something to consider here. You can’t leave your plants on a whim and just keep your fingers crossed. You’ll need a backup plan or trustworthy partner to help care for them while you’re away.

Lower Yield

Space is a big part of the equation when determining how large your plants will grow. Growing outdoors offers plants that yield up to 900 grams per meter squared, whereas indoors, the largest you’ll get is around half of that.

Given you can harvest more than once per year indoors, it could even out in the end — depending on your time commitment to the project.

The Legalities Around Growing Indoors

Understanding the specific legislation around the growing and consuming of marijuana is tricky. Uruguay, for example, legalized growing up to 6 plants for personal use in 2013. In the Netherlands, there is a policy of toleration. However, in the US it is still mostly illegal under federal law, aside from the 2018 Hemp Farming Act. This legalized growing marijuana so long as it contains less than 0.3 percent THC (read: it doesn’t get you high).

This makes it crucial that you research and know your state’s laws specifically, to avoid any troubles in the future. Factors that vary based on state include how many plants you can grow at once, which may limit your countering of the lower-yield point above.

In Colorado, for example, you can grow up to six plants and be in possession of 1 ounce — so long as you’re 21 years of age or older.

Steps to Growing Weed Indoors

Are you ready for all the choices you have to make where growing is concerned? We delve into detail later, but, in brief, these include the following:


Step 1. Choose Your Location
Step 2. Choose Your Grow Tent
Step 3. Choose Your Lights
Step 4. Choose Your Ventilation
Step 5. Choose Your Air Conditioning/Heating Units
Step 6. Choose Your Pots
Step 7. Pick the Right Tools
Step 8. Buy your Seeds
Step 9. Purchase Nutrients
Step 10. Pick your Growing Medium


Step 11. Germinate your seeds (3–10 days)
Step 12. Taking care of your Seedlings (2–3 weeks)
Step 13. Caring during the Vegetative Stage (3-16 weeks)
Step 14. Treatment during the Flowering Stage (8-11 weeks)
Step 15. Harvest and Dry your Buds (1-3 weeks)

It’s time to Build Your Grow Space!

This exciting phase is when you get to see all that forethought and dreaming come to life.

Step 1. Choose Your Location

Choosing a grow space is one of the first considerations you’ll make. Some key points to keep in mind include the following:

  • Ventilation/carbon filter
  • Discretion
  • Size of space
  • Noise

Ventilation and a good carbon filter are a must, which indicates you’ll need access to a nearby window where you can filter out the carbonated air. Otherwise, your house will smell of weed real quick.

Secondly, putting a grow box in a high-traffic area of your home isn’t a good idea. A laundry room or basement would be ideal as these spaces are private and allow you to keep things on the down-low.

Make sure to measure your space before assuming your grow box will fit. Take into account access to electricity and your ventilation system.

Lastly, your fans are bound to make some noise. Make sure your grow box isn’t too close to your home office or baby’s room. This would get annoying.

Step 2. Choose Your Grow Tent

How many plants are you looking to grow at once? What size space is available? These are questions to keep in mind when picking out a grow tent.

Smaller tents (approximately 2 feet by 4 feet) will house around 3 plants. However, if you are willing to spend a little more, larger ones have a capacity of up to 50(!) plants, depending on their size. Grow tents are available as small as 1m2. / 11ft2. all the way up to 10m2 / 108ft2.

The best-quality grow tents are made from a heavy-duty plastic covering and reflective insides to bounce all that light back to your plants. Flaps, adhesive taping, and zippers will be on the closing points to ensure no outside light or air enters.

Step 3. Choose Your Lights

There are two main types of grow lights:

HPS lights, despite being the older option, do offer an advantage when it comes to yield. Sinds the rise of the LED light its popularity has slightly diminished because HPS does have a few drawbacks.

The fact that it uses substantially more power is a common complaint. They also give off a lot of heat (which can be both an advantage as well as a disadvantage, depending on the circumstances). At the same time, they’re fairly budget-friendly, although they last nowhere near as long as LED lights.

If you live in a cold climate, HPS lights might serve you better as they tend to offer more heat (sometimes too much heat).

One of the major advantages of LED lights is that they last significantly longer. LED lamps also produce less heat, so additional heat in the winter might be necessary. They cost more upfront but offer enhanced longevity in return.

If your demand is a bit lower and your climate is mild or even warm, LED lights could be a better, more economical choice.

Step 4. Choose Your Ventilation

It might be obvious, but it’s also easy to forget. Weed smells! Sometimes it’s bad, other times not. Regardless, it can come with a very potent aroma that, most likely, you don’t want that floating around your house or in the vicinity.

A ventilation system cleans the air, dumping it outside. We recommend using a carbon filter, so the air pushed outdoors isn’t skunky either.

Other benefits of a ventilation system include:

  • Helps control humidity
  • Decreases pest and plant diseases
  • Keeps CO2 in balance
  • Lessens stress of heat
  • Circulates fresh air
  • Prevents pungent odor from getting out.

Depending on the size of your grow space, your ventilation system will differ, of course. Two of your main tools here will be an exhaust fan and an oscillating fan.

Keep in mind that oscillating fans below 6 inches in diameter won’t be strong enough for the job, regardless of your tent size. If those are all you have, use at least two of them.

Step 5. Choose Your Air Conditioning/Heating Units

If you have a medium-to-large size grow room, you may want to consider an air conditioning unit to increase the ventilation inside. Furthermore, your climate plays a large role as to whether you need to invest in such units.

Imagine you’re furnishing a home. Do you live in a hot climate where it’ll be difficult to maintain the temperature inside? An AC unit might be necessary. On the contrary, super cold climates will require further heating mechanisms than lights alone.

During the night or a “dark period,” the optimal temperature will be around 68°F / 20°C to 75°F / 24°C to give you an idea. If your temps are consistently falling below 59°F / 15 °C or above 80°F / 27°C, consider adding on to your ventilation system with AC or heat.

Step 6. Choose Your Pots

The most obvious thing to keep in mind here is that your pots should fit comfortably, not squished, in your grow tent. Cloth or fabric pots are an inexpensive option and also popular for other reasons.

See also  Weed And Seed

First, they offer adequate airflow, which means your plants will be prime for absorbing nutrients. Furthermore, you’ll benefit from good drainage as well. This can help you avoid problems such as root rot.

Look for fabric pots that are BPA-free and that have outside seams along the bottom, which help hold the pot together over time.

There are various sizes of pots available on the market, ranging from 1.5 – 5 gallons / 6 – 19 liters, with 3 gallons being the most commonly used. If you have sufficient room in your grow space, consider using the 5 gallon / 19 liter pots.

Why is the pot size so important?

Generally speaking, the larger the pots, the larger the plants. This will eventually benefit your yield which is, of course, your endgame.

Cannabis plants grow long, winding roots; if they are limited, your roots can become “root-bound”. This means that there is not enough room for the roots to grow. As a result, they cannot fully develop and will therefore not be able to absorb sufficient nutrients. This leads to nutrient deficiencies. Nutrient deficiencies will result in smaller plants or worse, your plants may even die!

3 gallon / 11 liter pots provide a good balance between pot size and room to grow – your cannabis roots have enough room for a decent grow, while the pot doesn’t take up too much space in your grow room so you can grow more plants in a limited space.

Step 7. Pick the Right Tools

Your initial space is now set up, and other tools are needed. These include:

  • Shovel: For digging, of course!
  • Watering supplies: A watering can is indispensable.
  • Scissors: Necessary for many tasks including pruning and cloning.
  • Hygrometer: Measures humidity, CO2 and more.
  • Temperature gauge: So you know how to adjust your AC/heat/lights.
  • Plastic gloves: Unless you don’t mind getting a bit dirty.
  • pH meter: You’ll need to keep an eye on the pH of soil and water when growing on cocos or hydro.
  • Rope: Often useful for rigging lights into place.
  • Bamboo sticks: To keep plants growing upright.

Depending on your budget, you can go as budget-friendly or high-end as you want here. Keep in mind that quality influences costs. While it may not be necessary to buy expensive plastic gloves, cutting corners on something like a hygrometer may not be wise.

Up next: Seeds, Nutrients and Growing Mediums

We warned you there was a cost to growing indoors and yes, you still have more items to purchase! Don’t fear. With a high-quality setup, some potent buds could be right around the corner.

Step 8. Buy your Seeds

It’s crucial to pick premium seeds — why else would you have invested in all this equipment? With high-quality strains, you’ll have better germination results, which is the start of your entire growing process.

A robust beginning will increase your chances of a better aroma, taste, growth, and yield. Our article the best indoor strains for beginners can help you distinguish from a list of great choices, for starters.

Step 9. Purchase Nutrients

You’ll require items such as fertilizer for your plants, starting when your little leafy babies are around three to four weeks old. What you use will depend on your growing medium.

You have to be careful here because under-fertilizing or giving too much can both lead to adverse effects.

Crafted bacteria and fungi solutions are useful for growth size and flowering success. One we love at Marijuana Seed Breeders is the Mycorrhiza Mix.

pH-equalizing solutions are also available when you come across difficulties where that’s concerned.

With all nutrients, there’s a variety of quality brands on the market.

Step 10. Pick your Growing Medium

Your nutrients, their dosage, and other factors all hinge on the type of growing medium you use. Each has its pros and cons:

Soil is not just a great option for beginners, in fact, it is recommended for everyone! Soil most resembles the way plants grow in nature. It retains a good amount of the nutrients it’s fed, easier to maintain your moisture balance and can be used multiple times. Aside from that, you will not have to sour your PHP and you will have more flexibility in terms of feeding times, which leaves room for error/experimentation since this option is the most forgiving.

On the downside, root-bound plants can appear quickly, which means the roots have outgrown their container. However, root-bound can easily be prevented by not pre-growing your plants for too long before you put them in bloom.

Another minor disadvantage is that replace the soil can be a tough job and you need to have room to dump it afterward or you’ll need to dispose of it.

A hydroponic setup means the plants are put directly into water only, and no other medium. Nutrients are absorbed quickly, and most strains grow more rapidly than with other mediums. Furthermore, nutrient issues show up right away and are easy to manage when they do.

Unfortunately, mold, fungus and root rot can occur since they’re planted in water. You have to stay on top of this to catch it right away. There’s also less of a buffer than with soil, which means it’s often recommended for advanced growers.

Types of hydro mediums include rockwool slabs, which may come as part of a growing kit.

Some say this is the “happy medium” of the two above. Plants placed in cocopeat tend to take in nutrients easily but might not hold them for as long as other mediums. Grow time falls in-between the soil and hydro setups.

The pitfalls here include a minimal buffer zone, should a feeding be missed, and high pH levels can occur easily, among others. It’s also only recommended for growers with at least some experience.

It’s Grow Time!

The growing process occurs in five distinct steps. We outline them, in brief, below. For further instructions, please follow up with our other guides.

Step 11. Germinate your Cannabis Seeds (3–10 days)

At Marijuana Seed Breeders, we prefer to use the Spongepot method. One of the major upsides here is that we include supplies, such as the soil enhancer. Want to know more about Germination? Read our in-depth guide: how to germinate weed seeds.

The temperature will need to remain at 72°F / 22°C – 79°F / 26°C throughout the process.

You’ll be waiting to see the root “pop” out during this phase. Once it has, the new seedling will begin to grow.

Step 12. Taking care of your Seedlings (2–3 weeks)

Leaves will start sprouting now, yeah! The plants will require 18 hours of light per day.

A baby seedling will initially have just one blade on its leaves. Once the blades begin to multiply and grow between five and seven blades per leaf, you’ll know it’s time for the vegetative phase.

Step 13. Caring during the Vegetative Stage (3-16 weeks)

Light, water, and food will be increasingly important at this juncture. Your plants will continue to need around 18 hours of light as they grow each day.

Watering methods will be intuitive and based on the looks of each strain. Are your bottom leaves starting to look droopy or a bit sad? Up their water intake. Stop watering when you notice a small amount of water pooling around the base of the plant.

What about nutrients? It’s important to read the labels of the products you’re using to determine the appropriate amounts.

Step 14. Treatment during the Flowering Stage (8-11 weeks)

Are you excited for those buds to appear? We’ve now reached that stage, and it’s an exciting one. Patience is a virtue, and at this point, and you’ll bring down the lights to 12 hours daily. During the off times, make sure your grow tent is well sealed to keep any light from coming in.

Step 15. Harvest and Dry your Buds (1-3 weeks)

Now you get to see the real fruits of your labor. Job well done.

When the hairy bits, called trichomes, around your buds start to change color from a white to an amber hue, you know it’s time to harvest. You’ll carefully cut the buds from the plants and prepare for the drying process.

There are two ways to go about it:

Hang Upside Down
This is a popular method, and you’ll do this directly after cutting the plants. You’ll notice the little leaves will shrivel up, and you can remove the larger ones. Work delicately around the buds to keep them, and their THC content, intact.

Use Drying Nets
You’ll cut them down similarly to the method above. Instead of hanging them upside down, though, you’ll use a net material instead.

Somehow, we’ve found the buds to look nicer this way than with the method above. This could be why businesses often use this method in commercial settings. However, we’ve also concluded that the THC content may drop with this method.

How Do We Know When They’re Ready?
Are the small branches bendable? If you can easily bend them, they need more time. Instead, if you find they break off, chances are the plant is done drying.

Do you live in a climate with high humidity? It could take longer for your plants to dry, so don’t fret and wait it out. An additional heater could help your cause.

Happy Growing!

This was it! Our guide to how to grow weed indoors!

The planning and procuring stage is a large part of the process. Get organized and stay that way. It’s an investment, after all.

The environmental controls, soil management and year-round growing are all reasons to start the journey indoors, as opposed to outside. Use the best materials you can afford and don’t skimp on seeds and nutrients. It’ll pay off in the long run.

Take advantage of our supplies on offer to get the most out of the growing experience. Best of luck to you and enjoy the process!

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

High-quality weed

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.

Multiple harvests

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.

Indoor space

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!

See also  Weed Seed Identification

Every space is different and there will be a learning curve to growing in yours.

Indoor climate

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.

Can you grow weed indoors without grow lights?

Just about all indoor weed growers use grow lights for their plants. Grow lights ensure your weed plants will grow healthy and strong, while maximizing yields.

In theory, as long as a cannabis plant can get at least 6 hours of full sun a day, whether inside next to a window, or outside, you don’t necessarily need a grow light, but pretty much all indoor growers use them.

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.

Air circulation

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.

How to regulate temperature and humidity when growing weed indoors

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:

  • Seedlings/clones: 75-85°F; ~70% relative humidity
  • Vegetative growth: 70-85°F; 40-60% relative humidity
  • Flowering: 65-80°F; 40-50% 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.

Regulating temperature

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.
How cold can weed plants handle?

When temperatures fall below 50°F, it can slow a weed plant’s growth and negatively impact the plant. Colder still and the plant could freeze.

Regulating Humidity

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.

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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:

  • Perlite
  • Worm castings
  • Bat guano
  • Biochar
  • Peat moss
  • Compost
  • 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.

Soil temperature for cannabis

Soil should be in the 65-75°F range, or about the temperature of your grow space. If it seems like soil is getting too hot under grow lights, add some water on the cold side next time you water.

What soil temperature is too hot for weed plants?

A soil temperature above 80°F for a plant isn’t ideal. When soil gets that hot it can be difficult for roots to uptake nutrients.


Hydroponics is a system of growing weed without soil. Plant roots are suspended in water, which is constantly recycled throughout the system. One of the main benefits to growing hydro is that roots have easy access to nutrients. Many argue that you can grow bigger, more potent buds with hydroponics.

Can you grow weed indoors without hydroponics?

Hydroponics is an advanced form of growing that experienced growers may take on, but indoor growing can be done with soil and pots for all levels of growing experience, and is much cheaper and easier than dealing with hydroponic systems.

Growing containers

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
Fabric containers

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
Ceramic pots

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.


Best water for growing weed

The cleaner the water, the better for your plants, but you don’t need to buy a bunch of distilled water. Generally speaking, if you’re only growing a few plants and your tap water is good enough to drink, it’s probably fine for your weed plants.

You can invest in an EC (electrical conductivity) meter, which measures the dissolved salts of your water, to be sure. Plain water should be between 50-300 ppm.

Ideal water temperature for growing weed

Water shouldn’t be too hot or too cold—keep water temperature between 65-75°F. Cold water can shock the plant and make it difficult for roots to absorb. Excessively hot water can damage plants.

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.

Do weed plants like warm or cold water?

If anything, use water on the cold side, rather than the hot side. Under 65°F will slow nutrient uptake, but water above 75°F can damage a plant.


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

    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.