To gain total control of your indoor growing environment, you need to take it a step further than having a grow tent or grow room. You’ve gotta have a totally sealed space – like a food storage box for the freezer. When you have holes and cracks, air and light leaks in from outside the garden. This makes it impossible to manipulate and customize the optimum conditions for your plants. A sealed grow space isn’t the least expensive approach, but it is what you need for the ultimate harvest.
This article is republished from Issue 4 of Garden Culture Magazine where it appeared under the title, The Sealed Indoor Garden. It was written by Tammy Clayton, Senior Editor.

Wait a minute! Surely, temps will soar with these lights blasting sunshine up to 18 hours a day. Nothing to worry about. In a sealed grow space you’ve got every aspect of your plant’s needs covered. The optimum temperature range for any plant is not very wide, and they don’t like radical changes. On top of the heat your grow lamps give off – hydro pumps, HID ballasts, dehumidifiers, and any other equipment inside the room create even more heat.

The solution to controlling the temperature is an air conditioner. Figuring out how much AC you need is simple. For every 1000 watts of light power you’ll need 4000 BTUs of cooling power. It’s not necessary to have central air installed. You will find a number of portable AC units designed just for the indoor garden available.

Having conquered temperature control, now you need to address your plants’ need for CO2. Without it, photosynthesis can’t take place, which won’t do your harvest any favors. A standard ventilation setup will give you normal atmospheric levels of CO2, but what if your crop needs more? In fact, why wouldn’t you want total control here too, since adding CO2 ups your harvest by 30%? It doesn’t make much sense to add it when the exhaust fan will just pump it out straightaway. You could simply shut down the ventilation system for a bit, but your plants will be baking in soaring temperatures. Radical change. Not good.

In a sealed room you can add more CO2 without losing it all before your crop can make use of it. So, how does one add CO2? There are a number of ways to accomplish this – propane burners, natural gas burners, and simple bottled CO2. In a small grow room, the bottled gas is sufficient. With a bigger room that’s running 6000 watts or more of lighting, it is usually the burner that’s opted for to supply the required 400-2200 PPM boost in CO2.

Naturally, a CO2 burner will create a new source of heat, but your AC unit will take care of that. Something you won’t need to worry about with the bottled gas, and there are also water-cooled CO2 generators available. If your room is small, you might want to add a diffuser to your bottled CO2 to deliver it automatically as needed by your plants.

Wondering about humidity being an issue? True, your plants in a sealed indoor garden will continue to transpire, and if left unchecked, high humidity can invite pathogens to attack, along with a marked reduction in plant growth. Standard venting is going to bring natural
humidity in from outside the grow room anyway, in most geographic locations. You will have explicit control of humidity levels day and night – 365 days a year with a sealed grow room. Using a dehumidifier that is the right size for your space will take care of your humidity woes in short order. Don’t skimp. Make sure it’s a good fit.

One thing that will get far easier to control in a sealed indoor garden is pests and disease. Of course, you still have to keep the space clean, and ensure you don’t inadvertently carry in bad stuff from outdoors, or from other people’s growing rooms and greenhouses. There are three ways these nightmares looking for a place to happen arrive in your garden – on your clothes or skin, on your pet, or through the fresh air duct. Granted, a well controlled environment can ward off some growing problems, because weakened plants from radical temperature changes, high humidity, and other things that are out of kilter, also invites pest and disease issues to take off like a rabbit from hell. Especially, if you’re not paying close attention to what’s going on in your garden on a daily basis.

The sealed grow room gives you complete control, and a garden free of anything that is going on outdoors. This really is the best way to protect your garden from negative outside influences. Growers have found great success in heightened efficiency using this concept for years, and it’s something every new gardener really should consider. Your job gets so much easier when you’re not battling Mother Nature. Or worrying about how other people’s need for spraying chemicals on everything in their yards is affecting your harvest. Chemicals? Well yes, if your garden isn’t sealed, anything floating in the air will enter.

Tammy Clayton

Tammy Clayton

Contributing Writer at Garden Culture Magazine
Tammy has been immersed in the world of plants and growing since her first job as an assistant weeder at the tender age of 8. Heavily influenced by a former life as a landscape designer and nursery owner, she swears good looking plants follow her home.
Tammy Clayton