First, you should know Al's set-up isn’t impressive because of size or technology, but because of ingenuity in dealing with adverse environmental conditions. Al lives in a hot, humid and extreme climate with temperatures reaching 115°F during the summer and -15°F during the winter.
Since he has no space in his house for his indoor garden, he built his grow room in the attic. Without any air conditioning, this space reaches 120° to 130°F during hottest part of the year. It would seem to be impossible to build something with an HID light up there and still regulate temperatures to the point where his vegetables and flowers could grow, but he had a solution.
He built a box of plywood and two-by-fours with standard home insulation. It had 4-in.-thick walls all the way around, and all the seams were caulked to create a super insulated, airtight box. Inside the box, there was a division for accommodating different day-length cycles. Al also built a door for his box that was 4-in. thick and insulated.
He even utilized refrigerator seals and hinges for a tight seal. Next, he installed a window air conditioner unit on one end. This window unit was sized for the volume of the box and successfully kept the inside cool. However, this window unit also added a lot of heat to the attic. The hotter the attic became, the harder it was to keep the inside of the box cool because the heat could not be exchanged by the air conditioner.
Al solved this problem by building a sheet-metal box around the back of the air conditioner and running ductwork to and from the insulated sheet metal box, attaching a fan to pull the heat off the backside of the A/C unit.
His solution enabled him to run one 400-W high pressure sodium and two 125-W compact fluorescent lights inside this box during hot summers and still keep temperatures below 80°F.
The compact fluorescents were set up on an 18-hour schedule and the 400-W HPS lamp was on 12-hour days. Al set his schedule so that his lights were off during the mid-day hours to avoid excessive temperatures.
He also installed a bottled CO2 injection unit because he was running a sealed system. The plants were set up on a drip irrigation system that consisted of a 5-gal. bucket with one pump on a basic timer.
He kept this bucket inside of the box to avoid the high temperatures outside the box.
He also covered the bucket to avoid creating excess humidity and losing his irrigation water.
The A/C unit was mounted on the end where the 400-W light was mounted and had its own built-in thermostat, which Al kept at 75°F. There was a thermostat set at 80°F in the section with the 18-hour day length.
This thermostat controlled a fan that pushed air from the 18-hour section to the 12-hour section. Therefore, the cooler air in the 12-hour section passively pushed into the hotter section.
Think of it like a recirculating nutrient system only with cold air. He also had a cool tube over the 400-W HPS bulb, which had its own separate vent for both intake and exhaust. Intake for the cool tube and the air conditioner sheet-metal box was brought in through a hole cut in a bedroom ceiling and covered with standard home ventilation grating. These ducts were exhausted through existing gable vents in the attic.
Once Al had this impressive homemade set-up made, it took some time to learn how to use it. He had sufficient previous growing experience, but never in such a confined space. He tried several methods of keeping his plants short and compact. Instead of using a trellis, which can be a hassle when removing a plant for transplant or harvest, he researched his horticultural resources and discovered bonsai.
The study of bonsai is complicated, but the basic idea is that you can shape a plant by bending and holding it without breaking or damaging the plant. This is similar to the trellis method, but it uses wire to bend the plant—Al used plant ribbon to bend the branches and tie them to the flower pot using a push pin.
Bonsai teachings also talk about root pruning, but this should not be done in a production setting. This technique is for keeping the plant small; Al’s objective was simply to manage vertical height.
Al did encounter a few other obstacles with his experiment. The first problem was that he had to carry water up a ladder into the attic every few days. He did not want excessive amounts of water in the attic in the event there was a leak or spill.
This could be corrected by simply having a reservoir in the home and using a pump to refill the 5-gal. bucket stored in the attic. After all, it’s always easier to drag a hose than carry buckets of water. The other major problem he had was humidity.
Every time he opened the door on this box, the humidity and temperature would shoot up and his ventilation system would have to restart cooling and dehumidifying the box (dehumidification was achieved by the air conditioner unit).
This problem could have been managed easier with an oversized window unit; however, since the set-up was in a hot humid attic, these problems will likely always be an issue.
This set-up is one of my favorites because of its creative design. Al dealt with many obstacles in his journey to grow at home.
This is a perfect example of how it is still possible to achieve your goal without the luxury of having expensive technology on hand by using a little ingenuity to use simple components that are readily available to you.