How to Build a Grow Box [Step-by-Step Guide]

A grow box or growing box is a term used to refer to a small box-like space where weed is stealthily grown. A grow box may not actually be a box but in a sense, it is a box where you can create the ideal environment for your cannabis plant to grow. This is the most popular way of growing cannabis indoors and it could also be yours if

  • You want to grow marijuana plants in secret
  • You want to grow just one or two plants for your personal consumption
  • If you cannot grow cannabis from where you are located because of the climate
  • If you want to grow exotic strains or landrace strains.

In short, growing cannabis using a grow box is a very intense way of cultivating weed. It is not for a beginner. You need to have all the complete materials and supplies to create the perfect growing environment for your plants. And most of all, you must have the skills to grow cannabis indoors considering you will be providing everything your plant needs (water, light, air, soil, and nutrients).

Things you will need

  • Marijuana plants in soil in a pot
  • An old closet or a box (the size depends on the number of plants and the type of strain)
  • Growing lamps
  • 2 small fans
  • Portable dehumidifier
  • Room thermometer and hygrometer
  • Power strip or extension cord


Choose the right kind of box or container where you will grow your weed

Consider the height and the width of the box depending on the adult size and dimensions of your plant. The size of the growing box depends on the number of plants you want to grow. It would be best to start with just one or two plants during your trial period.

Choose cannabis plants that will grow well in grow boxes or indoor growing

Choose plants that are also easy to grow and will fit in a small growing environment. If you are unsure, check out for important growing information about different strains.

If you are using an old compartment like a cabinet or a wooden box, make sure that the plant/plants you want to grow fits well. The plants should have plenty of space between each other. There must also be space for the grow lights, fans, and additional equipment that you wish to install.

Create two holes on opposite sides of the box

One hole near the top and one hole in the bottom. These are where your small USB fans will be installed; one fan will blow air in from the bottom part of the box (where cold or cool air settles) and the other fan will be at the top hole, blowing air out of the box (hot or stale air stays on top). Wire these fans together safely.

Now install the lights

Your grow lights should be able to provide adequate lighting for the number of plants you have. If you will just be growing one or two plants, an LED lamp would do. Find the highest rating LED lamp to get the best results and the best yields.

An LED lamp is recommended than other lamps because LEDs burn brighter and longer plus costs lower compared to ordinary fluorescent lights and HPS lights. There are many types of LED lamps, choose one that will fit inside your growing cabinet or box. Install this with brackets on top while the power cord should stick out of the box from the top.

Next, you must install a small humidifier

There are portable humidifier models that can fit in very small, compact spaces. Place this inside the grow box at the back of your plants.

Assemble your power strip

This could be an extension cord where you will plug your electrical components. This should be placed near the box and away from moisture, water, and direct sunlight. This must-have individual power buttons so you can easily power on or off your electrical components inside the box.

Install a thermometer as well as a hygrometer to strictly monitor the temperature and the humidity inside your grow box

Cannabis likes moderate temperatures and humidity; a bit higher or a bit lower temperature and humidity can dramatically affect its growth. Create a growing diary and a chart to monitor the growth, development, temperature, humidity, soil pH levels, watering, and feeding schedules for your plant/plants.

Add a lock and key outside your grow box

This is to further secure your growing space. This will also prevent children and pets from getting inside your grow box. Keep the key in a safe place and as a good measure, never tell anyone where your grow box is especially if growing and cultivating cannabis in your area is prohibited.

You can finish your grow box construction by painting it according to your preference

If you used an old cabinet, then you may refurbish this cabinet to look like new. You can sand it, paint it and give it a nice coat of varnish. No one would really suspect that you are growing weed from inside this lovely wooden cabinet.

Place your plants inside the grow box and power on your components

Water your plants daily only when the soil is dry. Watering your plants will increase the humidity inside the grow box and this can affect the health of your plants. So every time you water, open the box door for a while or until the soil has dried up.

Add fertilizer regularly and according to the growing or developmental stage of your plants

There are special fertilizer mixes available from garden shops and also from online sites. There are fertilizer mixes for cannabis plants’ developmental stage and also for the flowering stage. Find the one that fits your plants’ needs.

Take time learning how to make a grow box for your cannabis plants. Take time shopping for the best equipment and finding the right kind of strain that will grow well in this setup. Only by following these tips closely will you be able to grow cannabis using a grow box.

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