Growing Weed Indoors: Making the Perfect Grow Space

green plant with snow in macro photography
November 05, 2020

The steps to growing weed indoors are fairly straightforward providing you do your research. The journey to reaping your stash begins with germinating the seeds and ends with harvesting the buds. Throughout the life cycle, one thing is consistent. It happens in a dedicated cannabis growing space – be it a cupboard, a cabinet, a spare room, or a horticultural grow tent. Set it up correctly, and your plants will reward you with generous yields. Hence, you need to take the time to consider the merits before proceeding to build an indoor grow room.

Choosing your space to grow cannabis in depends on a variety of factors which relate to the size of the plant and also the temperature and conditions needed when growing it. For example, autoflowering marijuana seeds will grow into smaller plants than regular seeds and feminized seeds. Furthermore, you should ensure that whatever space you choose, you have enough space not only for the plant but also for the equipment needed to support the weed plant throughout its grow cycle.

Note that whatever space you end up choosing will have pros and cons and therefore you must adapt accordingly, all is not lost, you will just need to work around any issues you come across when growing your cannabis plants.

How Much Marijuana to Grow

Once you choose your marijuana seeds and how many of them you want to grow, you will have a better idea of what kind of space you need. Furthermore, you will have a better idea of the type of yields you can expect from your cannabis plants.

For example, most patients consume 1 to 2 grams of medical marijuana daily or 30 to 60 grams per month. You could then decide how many plants to cultivate based on which training method you plant to use.

Most patients who use medical marijuana consume around 1-2 grams of weed daily, meaning this is likely between 30-60 grams per month. Working under this assumption, you should be able to work out how many plants you need to harvest similar yields and sustain this amount. After you have done this, you can then look at the different training methods you would like to use for your weed plants.

Training your cannabis plants concerns physically manipulating your plants to alter their growth pattern, often improving the yield. This is a great way to boost efficiency when growing weed indoors at home.

To give you an idea, here is the number of plants per square meter:

  • Sea of Green (SOG): 4 to 16 plants
  • Pruning: 1 plant
  • Low Stress Training (LST): 4 plants
  • Screen of Green (SCROG): 1 plant

Most marijuana strains today can provide you with 300 to 600 grams per square meter. One harvest, theoretically, should provide enough yield for 5 to 10 months. If you start off with a high-yield marijuana strain you are sure to get better results.

For most people, and most strains, these are the number of cannabis plants that a given space can accommodate:

  • 2 x 2 feet: 1 to 4 plants
  • 2 x 4 feet: 1 to 6 plants
  • 3 x 3 feet: 1 to 6 plants
  • 4 x 4 feet: 2 to 9 plants

State regulations are a limiting factor in the number of marijuana plants you can grow at home. Most states where you can legally grow marijuana only allow up to six weed plants at a time. Furthermore, only three plants can be flowering while the rest remain in the vegetative stage.

Note: Be sure to check the local marijuana laws and regulations, and comply.

Growing Weed Indoors at Home

The purpose of growing indoors, for many, is a matter of necessity – lack of outdoor space is one of the top reasons. Others purposely choose so because it affords full control over the environment. Whatever your rationale is, the one thing that you need to keep in mind is to secure the growing space. In the USA, all states that legalized cultivating and growing weed indoors require you to keep it inaccessible to minors.

So, which part of the house could you grow marijuana?

You will be pleased to know that it could be anywhere. A cellar, if you have one, is an excellent choice. Because it is built beneath the ground, the earth provides excellent thermal insulation. It does not get excessively hot or cold, depending on the climate aboveground. Alternatively, it could be a spare room in the house, or an unused cupboard or closet.


The smallest space you can get away with is a cupboard that gives you about 1 x 0.5 x 2 meters (or approximately 3.2 x 1.5 x 6.5 feet). It allows you to grow a few marijuana plants, enough to sustain regular consumption to satisfy needs. Be it for recreational or medicinal purposes, the amount of bud you obtain should be adequate.

In the limited space, there is not much you can do except provide the basic needs of the cannabis plant. The two most important, apart from watering and delivering nutrients, are lighting and ventilation.

Generally, the higher the wattage, the more flowers you can harvest. In such a limited space, you could use up to 250 watts HPS. You would need to make sure you have adequate ventilation, ensuring heat is removed while also bringing in the fresh air.


Instead of a cupboard, an extra or spare cabinet is well-suited for growing marijuana because it has a larger space, therefore you could use higher wattage lamps to cover more area.

To give you an idea, the following are approximate dimensions of cabinet spaces and the number of HPS lamps (and wattage) it could accommodate.

1 x 1 x 2.5 3.2 x 3.2 x 8.2 (1) 400W or 600W
1 x 2 x 2.5 3.2 x 6.5 x 8.2 (2) 400W or 600W
2 x 2 x 2.5 6.5 x 6.5 x 8.2 (4) 400W or 600W
2 x 3 x 2.5 6.5 x 9.8 x 8.2 (6) 400W or 600W

The above dimensions only take into consideration the space occupied by the weed plants. If you plan on having an extra 0.5 meters, then you will have room to move around and work with the plants.

Room or Cellar

A spare room in the house is one of the best ways to grow weed indoors, they generally have more than enough space to grow marijuana while also conforming to the restrictions on the number of plants. Among its advantages is that you can connect fans to windows for better ventilation.

A cellar is most ideal as you would have excellent thermal insulation. Even if the outdoor climate is extreme, the ground around the basement space remains pretty much consistent. In other words, it does not get too hot or too cold.

You should never use the attic as it is the exact opposite of a cellar. Here, the temperature can quickly rise or drop. Its instability can wreak havoc on the plants. The same can be said of any room with windows facing the southward direction, where it gets hot during summer.

Any room that has at least 3 x 3 x 2.5 meters (9.8 x 9.8 x 8.2 feet) dimension lets you use up to nine 400W or 600W HPS lamps.

Grow Tent

Setting up a spare room or cellar is cumbersome. You would need to make sure that there is no light leak, for example. Also, dispersing the light is not efficient as some of the illuminations are not directed at the plants.

For simplicity, you could also opt for horticultural grow tents. These are commercially-made solutions that come in different sizes, ranging from small to full-room sizes. Its most significant advantage is convenience. They are designed to house plants and the equipment needed, as well as having provisions for fans and others.

The tent is built to eliminate even a tiny bit of light leak. Inside, its walls are made of reflective materials to redirect light to the plants. You can grow using soil as the medium or hydroponics.

What the Perfect Grow Room Needs

A perfect growing space does not necessarily mean that it has to be a spacious room with all the best horticultural equipment. It can be a cupboard or a cabinet too. What it comes down to is the needs of the cannabis plants and your ability to control the environmental factors affecting their growth and yields.

To that end, these are the things you need to ensure:


Let’s say you decide to use a cabinet inside a bedroom. Even if you were using a single 400-watt HPS lamp, any light leak could be annoying in the evening when you turn off the lights to sleep. If you are a particularly light or sensitive sleeper then light leakage can keep you up – it is that bright.

The plants also need to follow a fixed light cycle. Usually, it is 18/6 during the vegetative stage. During the flowering stage, they are on a 12/12 light cycle and sensitive to disruptions. If light leaks into the growing space during the dark period, then it could confuse the plants. Consequently, it may lead to reduced yields or complete failure. In some instances, one or more of your females could resort to hermaphroditism. Please note that light cycles can be different depending on the strains and types of cannabis you are growing, for example, autoflowering cannabis seeds require a different light cycle whereby you don’t need to alter the light cycle as regularly throughout the grow cycle.

Regardless of which space you ultimately end up choosing (including grow tents), you should check and make sure it is light proof. A gaffer tape may come in handy if you need to plug some holes. Growing weed indoors for beginners will be slightly different than it is for more experienced growers as you will learn a lot as you go, meaning your abilities will constantly improve with practice and experience.


The only air to come in and out should be by design (e.g., intake and exhaust vents and fans). Keeping your growing space relatively sealed, accomplishes four things:

First, you want to eliminate or minimize the aroma flooding the room or the entire house. Even if the smell of the strain you are growing is delightful to you, it could get overbearing for other people in the house. Unfortunately, you cannot prevent the odor from escaping into the neighborhood, unless you install a carbon odor-filter.

Second, sealing the growing space makes controlling the indoor climate far less demanding. By preventing drafts, for example, it is far more convenient for you to maintain the ideal temperature and humidity.

Third, you could minimize or entirely prevent bugs and other pests from entering the grow room and causing havoc on the plants.

Fourth, if you plan on augmenting the carbon dioxide levels during the flowering stage, you could concentrate CO2 inside the grow room instead of having some of it leak out.

Air Circulation

For your marijuana plants to thrive, they need a degree of air movement. Even in a cupboard, you should have a small oscillating fan casting a slight breeze to mimic outdoor conditions.

One of the benefits of ruffling the leaves is that the plant stomata have access to fresh air. Without air movement, the air becomes stale, and that inhibits efficient gas exchange. As a result, your plants will never attain their full potential. Their growth could be inhibited by weak stems and drooping leaves.

Another benefit of the slight breeze is that the stems and stalks develop to be thicker and sturdier. Think of those small movements as a means for the plants to exercise.

Maintaining adequate air circulation is also essential to the wet-dry cycle as they aid in evaporation. Furthermore, you can keep pathogens that cause moisture-related problems such as molds at bay.

Measuring Aids

You need a few digital meters to maintain the perfect environment for the plants. They could be individual meters or any of those 2-in-1 or 3-in-1 meters.

Thermometer. You need to maintain the ideal temperature, making sure it is not too hot or too cold.

Hygrometer. Like the temperature, you need to maintain the proper moisture level during the seedling to the vegetative stage, which is usually a little on the high side. During the flowering stage, it is lowered, and you need an instrument to take readings.

pH. Nutrients can be absorbed efficiently if the medium is slightly on the acidic side. Once it deviates to either extreme, it results in some minerals not being absorbed, causing a deficiency.

Total dissolved solids. Ideally, you would also use a TDS meter to measure the level of nutrients in the solution or any other media. It gives you an idea of when you should feed the plants, and that what you are providing is neither lacking or excessive.

Needs Determine the Type of Grow Room

As you can see, you have several choices on the type of grow room. Ideally, you should decide a format that best suits your needs. If you prefer a mind-bending cerebral experience, for example, then you would be growing Sativa strains. They would need more vertical space than plants from Indica seeds, so in this case, a cupboard may be too small but a whole room might be too much.

Sometimes, you may need to compromise. If you can only spare a cabinet, you will have to choose a strain that would grow nicely in the limited space provided. For example, autoflowering cannabis plants require far less space when growing while also being some of the fastest-growing cannabis plants, meaning they are great for cabinets and closets, even if you are just looking to test them out as potential spaces for bigger or more expensive grows.

Marijuana plants are versatile, this means you can use a few different training methods to adapt your plant to its grow space in the event your plant doesn’t fit properly. When it comes to growing cannabis indoors or growing marijuana at home, you should find an abundance of potential grow spaces all ready to be converted into the best grow space possible. Failing this, you can always buy your own grow tent and move forward with that.