Building a Refrigerator Grow Box

A grow box is a great way to grow plants in a self-contained environment with special lights, temperature, and ventilation. You can use it to grow flowers, vegetables, or herbs out of season. In five steps, and with intermediate skills, you can convert a discarded refrigerator into one of these productive grow boxes.

Step 1 - Prep the Refrigerator

Any old or broken fridge will work for this project. However, make sure that the seals between the door and the box are still able to shut tightly so your environment is maintained. To avoid potentially harmful effects of Freon, if any is left in the old refrigerator, have it removed by a professional.

Remove the wiring, air compressor, coils, shelves, and other material or equipment that adds unnecessary weight to your grow box. Save the shelves to use later. Clean the inside of your fridge and the shelves and drawers using a non-abrasive soap such as a garden disinfectant. Make sure you rinse all of the soap residue off when the box has been thoroughly cleaned.

Step 2 - Line the Refrigerator

Create light reflectivity by covering the interior of the box with aluminum foil and glue the foil to all interior surfaces (except the bottom). Allow two hours for the glue to dry.

Step 3 - Attach Grow Light

Determine the position for your grow light. Drill a hole through the ceiling or back wall of the box, large enough in diameter for the power cord (including the connector end that is larger in diameter) to fit through it.

Tip: Make sure to wear proper safety equipment when drilling. You may encounter insulation during the drilling process. When drilling the fan holes, remove the insulation wearing gloves and dispose of it properly.

Attach your light to the top inside the box, suspend it using a chain or cable, or simply place it on a top shelf. Feed the cord through the hole you cut, and pull the cord taut enough that no loose cord is dangling inside. Turn the light on to ensure it is reaching all the shelves. If not, consider installing a second grow light or repositioning.

Step 4 - Attach the Fans

To install exhaust fans, cut four holes in the rear wall of your box, large enough for your fans to fit flush into them. Two of the fans should be positioned near the top to exhaust air from the box, and two should be positioned lower to bring fresh air in. The fans should fit snugly inside the holes and be facing the inside of the box.

Alternatively, install one large exhaust fan at the back of the box and drill a hole below the fan for ventilation. The ventilation hole should be placed on the opposite side of the back of the refrigerator and slightly lower than the fan. It should also be roughly the same size as the fan.

Step 5 - Finish Grow Box

Replace your shelves and arrange your potted plants or starter seeds as you like. Again, make sure the light from your grow bulb is reaching all of your pots. Only open your refrigerator door for watering, maintenance, and harvesting. Grow boxes can be put in a closet, basement, or warm garage.

With just some simple assembly you can soon be enjoying your own flowers and fresh veggies, even with a blanket of snow on the ground!