Designing a Grow Room for Cannabis

So you want to try to grow marijuana indoors? The  proper equipment to set up a solid cannabis grow room takes a little bit of investment in terms of money to buy equipment and time to set everything up to give your marijuana plants an ideal growing environment. Hopefully with the weed from a grower’s first harvest, he or she can recoup their costs and then some funds for nutrients for the next grow. It’s kind of a pain in the butt to set up a marijuana grow room! In the fact, setting up a grow room will take a little bit of construction knowledge.

What are the benefits of growing cannabis indoors?

Once your marijuana grow room is set up properly the way it should be for your cannabis girls to flourish in, then you are golden for every future grow and you will just need to worry about recurring growing costs such as nutrients. One of the biggest advantages of growing marijuana indoors versus outdoors is that you can control a lot more factors so the quality of your weed should be better than the weed you would be able to grow outdoors. Growing cannabis outdoors means you are way more prone to a lot more environmental elements than a very sanitary, indoor grow room.

JOHNSTOWN, NY - AUGUST 19: Cannabis plants grow in the 'vegetation room' at Vireo Health's medical marijuana cultivation facility, August 19, 2016 in Johnstown, New York. New York state lawmakers voted to legalize marijuana for medical use in 2014 and the law took effect in January 2016. Currently, five organizations are allowed to grow and sell the drug for medical use in the state. New York's new law only allows people with 'severe debilitating or life threatening conditions' to obtain marijuana for medical use. (Photo by Drew Angerer/Getty Images)

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What factors should I consider when planning to build a marijuana grow room?

There are three things that a good grow room should have:

  1. good, safe location
  2. light-proof and
  3. airtight but be able to have sufficient ventilation

Picking a good location is a pretty important when planning out your marijuana grow room. I would suggest not growing next to any churches or schools or any nosy neighbors that might be inclined to contact local law enforcement about your little cannabis growing operation. The marijuana grow room should be light-proof because you will be manipulating the light from 18 hours to 12 hours for the start of your flowering cycle. Light leak can stress your cannabis plants. Your marijuana grow room should also be airtight because when your cannabis matures into buds, it will definitely start smelling like marijuana which some people that live around you might not appreciate the smell as much as you do. For this reason, we recommend a carbon scrubber to scrub the marijuana odor out of your grow room through your ventilation.

Why is ventilation so important when growing cannabis?

You’re grow space should also have a good way of providing sufficient ventilation and clean air free from pests. You will need to control the climate in your grow space so that will require you to think about how you are going to ventilate your cannabis grow room. The HPS grow lights that are typically used to grow marijuana also give out a lot of heat. Ventilation is the solution for sucking that heat out of your cannabis grow room. We recommend using an intake fan that will blow clean, filtered, cool air. You also need an exhaust fan that is first connected to your carbon scrubber and this carbon scrubber will keep your grow room smelling like marijuana.

Your intake and exhaust fan should be connected to a temperature controller that will be turning fans on when you need to lower humidity or suck the heat out of your marijuana grow room. There needs to be space for all this ventilation ducting and fans. Good ventilation will help prevent pests such as mites or other growing ailments such as fungus or powdery mildew from attacking your marijuana plants. Controlling humidity and temperature is super important growing cannabis indoors. If you can make your cannabis plants as comfortable as possible, they will repay you in fat marijuana buds coated in trichromes.


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What is transpiration and why is important to know when growing cannabis?

There is a thing about cannabis plants sweating and this called transpiration. Marijuana plants will transpire to help keep cool much like human beings sweating. This is especially when the lights and there is more heat in the room. Stomatas are the equivalent of pores and this water is released through those pores as CO2 is inhaled. When you first turn on your growing lights, stomatas will open up and close during your night cycle. It is good to have clean, circulating air in your cannabis grow room for a few reasons. Using a few oscillating fans in your grow room will help you accomplish the following: 1) circulate the air, 2) strengthens your weed plants, and 3) keeps pests at bay.

Where are you going to dry and cure your harvested weed?

You will need to have enough space to hang your harvested marijuana plants upside down while the buds cure to their true potential potency. You need to plan for some space for drying all of the weed that you have grown and harvested. Your drying space can be the same area as your grow room but the soil or anything that has moisture should be taken out while drying your weed. As mentioned before, your cannabis grow room needs to be light proof and airtight. This is especially true when you are drying your marijuana buds. Cannabis plants will continue to grow (which is not good if you want dense nugs) when you are hanging them so you want total darkness during your drying / curing period. The drying room should be cool like 60 degrees F. Additionally; your relative humidity should be 60%. Both can be accomplished with an AC unit and a dehumidifier. Dealing with moisture will also help reduce your chances of bud rot which sucks to see on your top kolas during harvest time.

Hydroponic versus soil is an age-old marijuana grower’s debate

Soil is a big pain in the ass. It is especially a pain in the figuring out what you want to do with your soil after your marijuana grow. Throw away or reuse? You save money reusing soil but it is certainly not as clean and you might be stuck with the same pests and problems that you had to battle your last grow. Hydroponics is an advantage to soil in this respect for marijuana growers. One of the biggest problems that I have seen with marijuana hydroponics set ups are that it is very easy to get root rot. It is very easy to contaminate your hydroponic tank. Another alternative is big rockwool cubes or maybe a combination of big rockwool cubes that can grow into a larger soil pot. They are certainly a lot easier to carry into your grow room than bags of coco soil. Whatever cannabis growing medium / method you choose as a marijuana grower, this recurring aspect is going to influence your grow room design.

How to set up HPS lighting for your cannabis grow room

Your cannabis grow space should have enough vertical height to hang your HPS lights on adjustable pulleys. The pulleys will adjust upwards as your marijuana plants grow taller. The HPS bulbs should never get to close to your cannabis plants or you will start burning them. This depends on what type of grow lights you have and how powerful they are but I generally keep 600W bulbs about 1 ½ feet from the top of my cannabis plants. Higher powered lights will need a greater distance from your cannabis plants. There are also high-end Gavita grow lights with it’s own lighting controller that you will not be adjusting. Marijuana growing tip: When you flip your lights, your cannabis plants will enter a pre-flowering growth phase and “stretch” out vertically during first two weeks of the flowering period.

You might need an electrician to help you wire 240 volt circuit to your lighting controller. A lighting controller will supply power to your ballasts and then to your HPS bulbs. If you are not comfortable with electricity, please do not mess with 240 volts! It will fry you! I would recommend having the ballasts outside of your cannabis grow room as these things produce heat and you will be wanting to reduce heat in your grow room.

Another tool that a marijuana grower has for dealing with height issues as your marijuana plants start maturing is an arsenal of advanced growing techniques such as topping or super cropping using trellis netting. Topping is the process of pinching off top nodes to create two new ones during the vegetative phase of your cannabis plants. Supper cropping is a method of growing the cannabis weaving horizontally in trellis netting so all buds get good light exposure and you reduce height problems. An advanced marijuana grower should know these training techniques anyways as these techniques positively affect yields.

Prep walls with Mylar coating so your cannabis plants get the most light

Your grow room should be light proof. One of the most important reasons for this is when you as a grower will especially if you in all circumstances as you will be controlling lighting from 18 hours to 12 hours to start the flowering period for your marijuana plants. Any little light leak will never be good for you as a marijuana grower. Additionally, your grow room should take advantage of all of the lighting in your grow room. For this reason, we recommend coating your side walls with Mylar coating. Mylar coating is reflective and will bounce light back on to your marijuana plants. It is also resistant to pest-resistant, mold-resistant, and it will make cleaning your grow room after every harvest a little easier.

Ideal Environment for your marijuana grow room?

Your cannabis plants are through seedling into from vegetative state you will want fairly humid conditions and the temperature inside your marijuana grow room shouldn’t getting much hotter than room temperature. Photosynthesis starts severely slowing down at 90 degrees F. You will want to monitor your temperature and humidity as you are going to the various phases of cannabis growth in your room.

You also need to control humidity along with your temperature. The humidity of your marijuana grow room will be influenced by your outside environment so be aware of that. Young cannabis plants love humid conditions as they will suck up the moisture but when your marijuana plants enter their flowering period, you will want to drop the humidity to mitigate the chances of encountering bud rot.

Here is a summary table of ideal temperature / humidity settings for your cannabis grow room during different stages of growth:

ideal temperature humidity for cannabis

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