In OGD 351, Julia Redman said she was about to install a basement greenhouse.
Thirteen months ago I did the same thing. I had a list of requirements that I wanted to be satisfied, if possible.
1. As much light as possible short of burning the leaves.
2. Broad spectrum of light for maximum growth and blooming.
3. Control of maximum air temperature by bringing in outside air.
4. Lots of air movement to keep the plant leaves cool.
5. Control of minimum temperature (New England winters!) with a small supplementary heater, if necessary.
6. A vapor barrier to protect the rest of the house from moisture.
7. A floor drain so I could water with a hose.
8. Movable benches to maximize growing space.
9. SAFETY: outdoor quality receptacles, no electric cords on the floor, ballasts suspended, etc, etc, etc.
10. A potting area inside my 'green' room.
I was able to meet all my requirements.
For lights I chose 1000 watt broad spectrum SunAgro HID lamps, suspended approximately 3.5 feet from the bottom of the bench. At this level the top of a one foot tall plant gets ca. 3500 foot candles
intensity. The lights are on 6 foot tracks. Growth has been great, and just about everything has bloomed well for me.
I bring in outside through intake shutters which open (insect screeing a must) when a 12 inch exhaust fan (Fantech 12-4) is on. This fan has the capability of replacing the air every 90 seconds. The fan is controlled by a Hunter low cost, low voltage programmable thermostat (K-Mart). At this time of the year it is set to go on at 60F and got off at 80F. Maximum room air temperature is no more than one degree F above the outside temperature in the shade.
I have a 12 inch Schhaeffer greenhouse fan high in one corner of the room, and a 16 inch Vornado one foot above the floor in another corner. All the leaves are moving all the time, and the leaves of the tallest plants remain cool to the touch (6000+ foot candles).
The room stays warm enough at nights on the coldest days, and are adequately heated by the lamps. I do use a small auxiliary electric heater (three feet off the floor and away from the growing area) in case my intake shutter freezes open, and to raise the room temperature more quickly. It operates off its own thermostat.
The room's interior walls and ceiling are constructed of a sheet reinforced plastic (vinyl, I believe) called Kemlite. It is used to line industrial kitchens and car washes. It comes with joining and corner strips. The bottom is caulked with high quality silicone sealer. All holes, e.g, for screws, are filled with silicone prior to inserting. There is an additional plastic sheet in the ceiling. The room is 12+ feet by 16 + feet, and the ceiling is ca 7 feet high.
I do have a floor drain, and I do water with a hose. I have two, 33 gallon plastic barrels (Home Depot), one for RO water and the other for fertilizer. I use a 1/3 HP submersible pump and a 25 foot 3/8 inch coiled hose(Charley's Greenhouse; home Depot is cheaper). Delivery rate is about 3 gpm.
There are three benches on wheels: 2, 12 feet X 3 feet and 1, 10 feet X 3 feet. There is a lamp on a six foot rail for each. I need a better wheel system; they occasionally come off. The benches were built out of cedar locally by a company that erects greenhouses. They have expanded metal bottoms. i have attached various fixtures for hanging plants.
The electric outlets (duplex) are about 5.5 feet above the floor and are designed for outdoor use. Each lamp and its drive motor are attached to the same duplex outlet. There is a timer for each light and its motor, located outside the room. The three lamps are on a single 25 amp circuit which has proven to be quite adequate. All other electric components are on a different circuit. There are ground fault interrupters.
There is a six foot X three foot potting bench which is adequate, and a laundry tub for scrubbing pots.
What would I do differently? Not a whole heck of a lot.
I will be delighted to supply additional information to anyone who wants it.
Martin
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