Log in

Previous Bloom | Next Bloom

Building an Indoor Greenhouse Frame

Originally published at The Suburban Garden. Please leave any comments there.

Small suburban gardens usually mean no space for a roomy outdoor greenhouse.  This tabletop greenhouse works great indoors.

Small suburban gardens usually mean no space for a roomy outdoor greenhouse. This tabletop greenhouse works great indoors.

After a couple of years with our previous indoor greenhouse, we’ve decided to improve the design by rebuilding the frame. Our first version had a few issues that needed to be addressed:   

  1. The frame of the greenhouse was permanently attached to the light system frame, which meant we were unable to easily remove it if we needed to.
  2. The lights were outside of the frame. We would like them inside the frame to make use of the small amount of heat that the lights will give off inside the greenhouse.
  3. The greenhouse only had one zipper, placed in the middle, which made inserting and removing plants difficult.
  4. The top of the greenhouse didn’t have a middle support beam, and after a while, the plastic started to sag.
  5. We used Gorilla (gaffer) tape on the plastic. This was a great idea at the time, because it is very strong, but the adhesive eventually started to break down under the UV lights.

This article will outline how we improved the design, and what materials we used. Our design works with the Lee Valley Tabletop Floralight unit, which makes it easy because it has its own framework underneath. If you are building a larger unit, your measurements will have to be customized to fit your light system. If your own unit doesn’t have framework, you may not want to use the same connectors we used, as they are made of rubber and are attached to the underlying framework to keep them from wiggling.

The materials used for the framework.

The materials used for the framework.


1. Plastic: Nackten shower liner (Ikea).
2. Zippers: Two 22″ fabric zippers.
3. Connectors: Eight 3-prong & Four 4-prong Cane Connectors.
4. Tape: UV Resistant Tape.
5. Framework, 3/8 poplar dowels:
- 4 x 52″
- 6 x 28″
- 6 x 21″




These rubber cane connectors make attaching the dowels simple.

These rubber cane connectors make attaching the dowels simple.

  1. Cut the wooden dowels to the correct sizes and sand the ends.
  2. Push the longest dowels through 2 opposing arms of the 4-arm cane connectors, so that the connectors are in the middle of the dowels. Do this with all four of the long dowels.
  3. Push the end of the longest dowel through one arm of the 3-arm cane connector, so that the connector is sitting on the end of the dowel. Do with with each end of the longest dowels.
  4. Push the shortest dowel through an open arm on the 3-arm connectors. Do this with all of the shortest dowels, creating two large rectangles.
  5. Add one of the short dowels in the middle of one of the rectangles, creating additional support. Do not do this with both rectangles – you will add the last piece after placing the framework over the light system.
  6. Lay the bottom rectangle (the one without the cross-piece) flat on the floor, with the empty connector arms facing up. Push one end of each of the medium dowels into each of the open connectors (6 in total). Once this is done, push the other end of the medium dowels into the open connectors on the other rectangle, completing the primary framework.
  7. Install the framework around the light system, and complete the framework by sliding the final medium dowel under the light system and pushing the ends into the remaining open connectors in the middle.
  8. If you find the framework shifts, attach it directly to the light system. I prefer to use zip-ties because they don’t leave a sticky residue, but tape also works.

    The completed framework.

    The completed framework.

There are many different ways to attach the plastic. Since I was using a shower curtain, I used zip-ties in the curtain’s holes to attach one end, and UV resistant tape to attach the rest.

User gaffer tape to attach the fabric zippers.

User gaffer tape to attach the fabric zippers.

  1. Cut the plastic to the correct size for all dimensions (top and sides) of the greenhouse.
  2. Wrap the plastic around the greenhouse, wrapping the ends up as if it were a present.
  3. Make two cuts in the plastic, on each side of the front. This is where the zippers will go.
  4. Attach the fabric zippers with gaffer tape, or another tape with strong adhesive (the UV resistant tape will not stick to the fabric zipper).
  5. Use two pieces of tape along the bottom of the front flap to keep it shut. UV resistant tape is best because it will separate from the bottom of the greenhouse easily. Keep in mind that you will have to change the tape from time to time as it collects debris.
A piece of UV-Resistant tape acts to hold the plastic against the greenhouse.

A piece of UV-Resistant tape acts to hold the plastic against the greenhouse.

You now have a plastic cover for your greenhouse which allows you to open the entire front, making it easier to water plants, add and remove plants, and air out the unit.

Here are a few other items I use in my greenhouse that make things run smoothly:
1. Double-outlet timer: I keep this on a 12 hour cycle, running at night (to take advantage of cheaper hydro rates).
2. Two heat mats: to help with germination, and to raise the ambient temperature inside the unit.
3. A thermometer / hygrometer: to measure the temperature and humidity in the unit.
4. Shelves: my light system can be raised and lowered; however, I often have plants of varying heights. I find the use of shelves help easily ensure that different sized plants are as close to the lights as they need to be.

Plants to the left...

Plants to the left…

...and plants to the right.

…and plants to the right.