Build Your Own Grow Tent

 

As with any building or gardening project, you need to have a plan before getting started. The same applies to building an indoor grow room. The more precise your plans are the better the chances that your project, and ultimately you harvest, will be successful. There are several critical steps you will want to follow to ensure your success. These will be the same whether you simply want a small grow tent or a larger enclosed structure.

SPACE AND LOCATION

First you will need to determine how much space you have and where that space will be. Then decide approximately how much cannabis you want to cultivate. The average amount one uses per month will of course vary but the typical personal/medical amount consumed is generally 1 or 2 ounces a month.

Location is important for a couple of reasons, one being that you want to make sure you have complete control over the environment within the enclosure. You must be able to easily adjust temperature, lighting, airflow, watering, etc. Cellars are a popular choice for many since heat and cold tend not to change rapidly and will keep your enclosure free from frost or excessive heat.

If space is really at a premium, a pantry can be successfully converted to meet your needs. You will however want to make sure the space is at least 2.5 x 1.5 x 6.5 feet.

CLEANING OUT YOUR SPACE

Ensure that the space is thoroughly cleaned out. It is important that you remove everything that may be in the room or space you plan to use. There should be absolutely nothing in there except for the floor, ceiling, and walls. This step may seem like a no-brainer, but anything left in the room can adversely affect the environment and ultimately a successful harvest. For example, a window that is not properly sealed can let in air that may prevent you from controlling the temperature as well as the humidity within your enclosure; not to mention pests that can adversely affect your plants.

BEGIN BUILDING

You can now begin construction on your grow room or tent. Of course, if you have decided to purchase a grown tent kit, and your tent is set up, you can begin the planting phase. Getting all the right equipment and materials is the first step. All enclosed growing environments will require:

  • Structure frame – The most cost-effective way to build a tent structure is by using PVC piping which should be no less than 2 inches in diameter. The size of your tent will determine how much equipment you will need for lighting and ventilation. Keep in mind that both these items may be hung from your frame so make sure your frame is able to hold the weight.
  • Sheets of reflective film – This is known as Mylar or can be referred to as ‘Panda Film’. The inside (silver side) is highly reflective allowing for maximum light absorption, while the outside blocks all external light from getting into the grow environment. Make sure you have just one, easily accessible opening. When wrapping the Mylar around your frame, make certain that it is tightly wrapped on all sides using high quality duct tape where necessary. The easiest way to do the wrapping is by beginning with your first two walls followed by the second two, while always remembering to tape wherever needed.
  • Ventilation – You will need to determine where the ventilation system feeds out of your structure and where it will feed into it. Proper air circulation is vital to keep your plants healthy and free of pests, mold, and other disease. The air within the enclosure must be exchanged at a minimum rate of once every three minutes. This is where an exhaust fan comes in and they are typically rated as CFM (cubic feet per minute). You can figure out what CFM you will require by dividing the volume of your room by 3 minutes. So, if the volume of your room is 350 cubic feet, you simply divide 350 Cubic Feet by 3 minutes giving you just over 166 CFM. This will be the minimum CFM number you will need.  

You will however need to keep in mind that there are other factors that must be taken into account which will affect your intake and exhaust system such as:

  • Lighting – Grow lights like HPS and Metal Halide ones do run hot and will affect the heat inside the grow room as do HID (high intensity discharge) lights. In order to compensate for the lights, you should add about 5% to the CFM number you originally came up with. If your grow room does run hot you should consider adding upwards of 25% to your original CFM calculation. Additionally, in an environment that is both hot and humid, you made need to add closer to 40% to your original CFM number.
    • Air Filters – Carbon air filters create a certain amount of friction in your system. If this is the case, you will need to add and additional 20% to the CFM rating to the previous step.

Ventilation and air circulation are perhaps one of the most critical steps in setting up a controlled environment within your grow room. It will control the temperature, humidity, and general air quality and is therefore vital to a successful harvest. We previously explained the function of passive and active intake and how to ensure they are installed for maximum benefit. (Here we will create a link to the previous article) Keep in mind that even with the best exhaust system in place, a small oscillating fan is a good idea in order to have air blowing both above and below your plants. This will help prevent even small areas of humidity or hot spots that can occur in the air. Keep in mind that the leaves of your plants add to the humidity levels and left unchecked can cause bud rot, mold, and mildew.

If your exhaust system is not controlling the air quality properly, humidifiers and dehumidifiers are highly recommended. Optimal humidity levels differ depending on the stage that your plants are in and should be kept as follows:

CLONES 70 – 80%
VEGETATIVE 40 – 60%
INITIAL FLOWERING 40 – 50%
FINAL FLOWERING STAGE < 40%

While ventilation and air circulation may seem to be a complicated process, simply using the volume of your grow space will make the necessary calculations much easier.

Convenient Source of Water

After investing time, money, and, proper planning to have the best grow structure and environment for your plants, you don’t want to end up having to haul water up and down stairs or the other end of the house just to water your plants. To avoid this, make sure you have a convenient water source close to your grown room. One way to accomplish this is by having your structure close to a water heater or your washing machine. You will need to attach a water manifold that has an on/off valve to both the hot and cold water hose bib. By using a water hose that can reach your grow room, you will be able to conveniently water your plants whenever you need to. It is also a good idea to have a misting attachment on the hose.

Lighting

At this stage of your build you will need to mount your light holders to your ceiling and of course decide whether you are using hooks or chains. Regardless of what system you use, always make certain that your structure and light holders are capable of supporting the lights. You will also want to check to see how much space each one takes before you mount any holders to the ceiling. Keep in mind that some of the larger glass lights can weigh in excess of 25 or 30 pounds a piece.

Although you will want to spend some time thinking about which light source you choose, there really is no need to complicate or over think the issue. The first thing to look at is the wattage and then of course the impact on your electricity bill. You will also want to take into consideration the amount of heat your lights will produce as this will affect the temperature of you room. Also be aware that lights that are too strong and perhaps too close to your plants are counter productive and can cause plants to wither and burn.

While there are a number of lights that can be used in a grow room, we will only be talking about the three most common and reliable light sources.

  1. LED – LED (light-emitting diode) This mode of lighting, with its evolving technology, has quickly become the desired choice for most cannabis growers. These lights have come a long way and now, in many cases, superior to the old HID lighting systems.
  2. HID – If you are using HID lighting, between 400W and 600W are the best for growing in an indoor space. It is important that the lights are level when hung and should be from 30cm to 50cm above the canopy. As your plants grow you may need to adjust the height of your lights so make sure they are hung with either rope ratchets or hangers that can easily be rolled. Resist the urge to add more lights in the hopes of increasing your harvest. For one thing they will add heat to your environment and while the bulbs are safe even at 20cm to your plants, light absorption is not evenly distributed and will not reach the lower parts of your plants.

AIR CIRCULATION

Air circulation is critical to a successful harvest for a number of reasons including:

  • Humidity Control – Remember that plants produce water vapor which in turn increases the humidity in the environment.
  • Temperature Regulation – Although lights are a must in any enclosed grow room, they do add heat and this excess heat must be controlled through proper air circulation via adequate ventilation.
  • Disease and Pests – This is a common and critical problem that can wipe out your potential harvest. Proper ventilation or air circulation will eliminate this danger.
  • C02 Absorption – Plants need to absorb the right amount of C02 which they do naturally in an outdoor environment. Because C02 levels in an enclosed space are continually on the decline, it is important carbon dioxide be brought into your grow space from outside.
  • Strong Plant Stems – Plants that grow outdoors are able to naturally strengthen and stabilize their stems. Having a good ventilation system indoor will help them maintain their stem strength resulting in a healthier plant.

A good ventilation system will depend largely on adequate carbon filters and fans within your grow space. As discussed earlier, the two types of fans are Oscillating fans and an air extractor fan system. (Here we will have a link to that in the previous article)

At first glance, it may feel like the steps you need to take to build a successful indoor grow structure may seem overwhelming. If you simply take one step at a time and concentrate on getting the one you are working on right, you will be surprised at just how quickly it all comes together and before you know it, you will be ready to start planting. The important thing to remember is that each step of your project is critical for a successful harvest and rushing through any one step will result in more work to get it right.