Indoor garden design is all about creating the perfect environment for growing cannabis. There are two types of grow rooms: sealed and vented. Sealed rooms recirculate and rejuvenate air within the room. Vented rooms replenish the grow environment with fresh air from outside. The design choice has profound impact on garden design, budget and performance. Sealed rooms yield better, but they are expensive to build and operate. Vented rooms are simpler and cheaper, but yield less and are more susceptible to pests. The purpose of both designs is temperature, humidity and atmospheric control.
The choice between a sealed and vented grow room has a lot to do with hot grow lights. Indoor gardeners need to get rid of that excess heat, or else their plants will cook. Sealed gardens rely on air conditioners to remove heat from the grow room. Air conditioners are an effective, but inefficient way to remove heat. It takes about 6,000 BTU of air conditioning to manage the heat from a 1000w grow light. Air conditioning uses almost as much electricity as lighting in a sealed grow room!
Vented gardens use ducting and in-line fans to remove hot air. Intake fans replace it with cooler outside air. Thermostats control temperature, somewhat, by cycling ventilation on or off. Fans are cheap and efficient, but they are only as effective as the weather outside. Vented gardens work best in cool climates.
Plants transpire water into the air, causing humidity to rise. Indoor gardeners need to remove that moisture or else the garden will become too damp. Too much humidity causes powdery mildew and bud rot.
Sealed rooms trap moisture like a terrarium because air cannot escape the garden. Air conditioners remove some humidity; dehumidifiers remove the rest. Like air conditioning, dehumidifiers are effective and precise, but electrically inefficient. They also increase the burden on air conditioning because dehumidifiers generate heat.
Vented gardens use intake and exhaust fans to remove humid air. Intake/exhaust fans are affordable, but they are less precise. That’s because the outside weather affects the efficacy of ventilation systems. Venting dehumidifies better in dry weather.
Fresh Air and CO2
Plants need lots of carbon dioxide for photosynthesis. Without CO2, they will suffocate and grow slowly. Vented gardens fix this problem with fresh air intakes. Sealed gardens rely on carbon filters and artificial CO2 supplementation to recycle air. CO2 supplementation is impractical in a vented room because air constantly leaks out. In fact, the goal is to exchange all the air in the room every few minutes!
CO2 supplementation gives sealed grow rooms a major performance advantage. CO2 is like steroids for plants. Artificially elevated CO2 levels makes plants grow bigger, faster. But again, this performance comes at additional up-front and operational expense.
Pests & Pollution
Even a vented garden should seal cracks and gaps in grow room walls. That’s because light leaks and drafts attract pests and disease into the garden. Intake and exhaust ports also attract small particles, much like hoses on a shop vac. Once inside, air recirculates slowly and dust settles– like inside a vacuum canister.
Fix the “vacuum cleaner effect” by adding a HEPA filter to the air intake. Add UV air scrubbers to sterilize air as it passes through intake ducting. Recirculating carbon air filters provide redundant filtration inside the room. The intake air flow should exceed exhaust rate to create positive air pressure. This prevents passive air intake through gaps, such as gaps around the door.
Sealed gardens are physically separated from the outside world. Because air is recycled, it is much harder for insects or pathogens to infiltrate the garden. Sealed gardens also use recirculating fans and carbon filters to remove airborne debris.
Cost to Build and Operate
Vented grow rooms are great for small-scale growers, especially during the winter. They are the best option for budget-conscious start-ups. Vented gardens are cheap to build and operate so they are a good option for temporary garden spaces. They also use much less electricity than sealed grow rooms. Vented gardens are a good value and they can produce solid results.
Sealed grow rooms offer greater return on investment. They yield more quality and quantity, faster. This makes them the best option for commercial cannabis production. The return on investment is greater than a vented room. Sealed rooms are horticultural perfection through advanced technology.
Either design can create amazing, or disappointing results. The key to success is the knowledge and planning to create the best design for your unique situation.