How to Make a Grow Box for an Apartment Balcony

Place eight pots on the bottom of the 32-gallon container. Cut the container’s lid down 1 to 2 inches, or as needed for it to fit inside the container on top of the pots. The lid doesn’t have to fit exactly to the container. Try to keep the outer part of the lid as one piece because you need it later.

Draw circles on two opposite corners of the lid that are about the same diameter and location as the pots below, and cut these circles out. Cut out another circle in the lid large enough to accommodate the PVC pipe. The large circles will act as wicks when filled with soil and allow water into the upper part.

Drill holes spaced 2 inches apart over the entire lid. Drill five or six holes in the bottom 6 inches of the PVC pipe, and place the pipe in the hole in the lid. The PVC pipe is used to fill the bottom of the container with water. Place duct tape around the entire edge of the lid and the pipe to seal them to prevent the soil from filling up the water reservoir below.

Mark and then drill three or four holes on both sides of the container, about 6 inches from the bottom. These holes will be just below the taped lid, and water will come out of these holes to let you know when the bottom is filled.

Drill one hole on each of the long sides of the container above the lid. Attach a wire to these holes that goes across the center of the container. This will keep the sides of the filled container from bulging. Place the grow box on your balcony in the location needed before adding the soil.

Put potting soil in the holes in the corners until they are full, and cover the bottom with about 3 inches of soil. Firm the soil down and finish filling the container. Water the soil to moisten it and firm it again. This is the only time you need to water this way.

Spread 2 cups of a granular fertilizer, such as 13-13-13 or 15-5-10, down the center of the container in a 3-inch-wide band. Cover the fertilizer with a thin layer of soil.

Place the garbage bag over the top of the soil, and cut a hole in the bag to allow room for the PVC pipe. Put the lid on top of the container to hold the bag in place. The bag will hold in moisture and prevent rainfall from washing away vital nutrients.

Cut holes in the plastic as needed to place plants in the box. Fill the bottom reservoir with water until it drains from the drainage holes on the sides. Continue to fill the container with water weekly, or more often if needed to keep the water reservoir from drying out.