Tiered shelving for plants can be a very useful way to grow a large number of plants in a small space. Even in the brightest window, however, upper shelves will block the light from getting to plants on lower shelves. One way to mitigate this effect is to build plant shelves with built-in lighting. Commercial lighted plant shelves can cost hundreds of dollars, but you can build your own cheaply and easily using PVC pipe as the framework, and installing the lights yourself.
Cut eight 48-inch lengths of pipe, using the hack saw.
Cut eight 21 1/16-inch lengths of pipe.
Cut eight 12 3/4-inch lengths.
Cut eight 15 1/2-inch lengths.
Cut 16 lengths that are 1 3/8-inch.
Glue tee connectors to both ends of each of the 48-inch lengths using the PVC adhesive. The middle branch of the tee connector should be glued to the end of the 48-inch pipe so that the tee connectors on both ends of each pipe are parallel.
Glue tee connectors to both ends of each of the 21 1/16-inch pipes. Ensure that the connectors are parallel on the ends of each pipe.
Insert the 1 3/8-inch pieces of pipe into one of the free ends of each tee connector attached to the long 48-inch pipes. Then insert an elbow connector attached to one of the shorter 21 1/16-inch lengths onto the other end. Now you have two sides of a 4-sided rectangular shelf frame. Repeat the process to create a full four-sided shelf shelf frame. Construct four of these frames
Place a 15 1/2-inch length of pipe at each corner of the bottom two shelf frames. Insert the 15 1/2-inch pipes into the upward-facing tee connector openings on the bottom shelf, connect the lower part of the tee connectors on the next shelf to those four upright pipes, then put four more upright 15 1/2-inch pipes into the upper openings of the tee connectors on the second shelf.
Connect the third shelf to the upright pipes coming from the second shelf and then insert the eight 12 3/4-inch lengths of pipe to connect the top two shelf frames via the downward- and upward-facing tee connectors at each corner, as in Step 9
Drill three holes in each long side and one hole on each short side of the bottom shelf (which will have no light hanging beneath it) and then drill a corresponding hole on the long and short sides of the plywood. Use a drill bit that is slightly thinner than your wood screws.
Connect the plywood to the top of each shelf with wood screws.
Wrap the chains of the light fixture around the shorter horizontal PVC pipes on the short sides of the top three shelves and secure the chains to themselves so that they hang directly below each tier of the shelf. The plant trays (which must be waterproof and without drainage holes) will sit directly on the back of each light, except on the bottom shelf. This allows the top tier to receive natural sun, while all the other shelves will receive supplementary artificial light.
Arrange the plant trays four to a shelf.