A growroom (or grow room) or growth chamber is a room of any size where plants are grown under controlled conditions. The reasons for utilizing a growroom are countless. Some seek to avoid the criminal repercussions of growing illicit

cultivar A cultivar is a type of cultivated plant that people have selected for desired traits and when propagated retain those traits. Methods used to propagate cultivars include: division, root and stem cuttings, offsets, grafting, tissue culture, ...

s, while others simply have no alternative to indoor growing. Plants can be grown with the use of

grow light A grow light is an electric light to help plants grow. Grow lights either attempt to provide a light spectrum similar to that of the sun, or to provide a spectrum that is more tailored to the needs of the plants being cultivated (typically a varyi ...

sunlight Sunlight is a portion of the electromagnetic radiation given off by the Sun, in particular infrared, visible, and ultraviolet light. On Earth, sunlight is scattered and filtered through Earth's atmosphere, and is obvious as daylight when t ...

, or a combination of the two. Due to the heat generated by high

power Power most often refers to: * Power (physics), meaning "rate of doing work" ** Engine power, the power put out by an engine ** Electric power * Power (social and political), the ability to influence people or events ** Abusive power Power may a ...

lamps, grow rooms will often become excessively hot relative to the temperature range ideal for plant growth, often necessitating the use of a supplemental ventilation fan.

Growing methods

The plants in a growroom can be grown in

soil Soil, also commonly referred to as earth or dirt, is a mixture of organic matter, minerals, gases, liquids, and organisms that together support life. Some scientific definitions distinguish ''dirt'' from ''soil'' by restricting the former te ...

, or without soil via means such as

hydroponic Hydroponics is a type of horticulture and a subset of hydroculture which involves growing plants, usually crops or medicinal plants, without soil, by using water-based mineral nutrient solutions in aqueous solvents. Terrestrial or aquatic plan ...

s, and

aeroponics Aeroponics is the process of growing plants in the air or mist environment without soil or an aggregate medium. The word "aeroponic" is derived from the Greek meanings of ''aer'' ("air") and ''ponos'' ("labour"). It is a subset of hydroponics, ...

Vermiculite Vermiculite is a hydrous phyllosilicate mineral which undergoes significant expansion when heated. Exfoliation occurs when the mineral is heated sufficiently, and commercial furnaces can routinely produce this effect. Vermiculite forms by the wea ...

perlite Perlite is an amorphous volcanic glass that has a relatively high water content, typically formed by the hydration of obsidian. It occurs naturally and has the unusual property of greatly expanding when heated sufficiently. It is an industrial m ...

coconut husk The coconut tree (''Cocos nucifera'') is a member of the palm tree family (Arecaceae) and the only living species of the genus ''Cocos''. The term "coconut" (or the archaic "cocoanut") can refer to the whole coconut palm, the seed, or the f ...

and

rockwool Mineral wool is any fibrous material formed by spinning or drawing molten mineral or rock materials such as slag and ceramics. Applications of mineral wool include thermal insulation (as both structural insulation and pipe insulation), f ...

are common components in soilless mixes for indoor cultivation.

Lighting

The three most common varieties of artificial lighting for indoor growing are

high-intensity discharge lamp High-intensity discharge lamps (HID lamps) are a type of electrical gas-discharge lamp which produces light by means of an electric arc between tungsten electrodes housed inside a translucent or transparent fused quartz or fused alumina arc tu ...

s (the most prevalent for this application being:

sodium-vapor lamp A sodium-vapor lamp is a gas-discharge lamp that uses sodium in an excited state to produce light at a characteristic wavelength near 589 nm. Two varieties of such lamps exist: low pressure and high pressure. Low-pressure sodium lamps are ...

s for flowering and

metal halide lamp A metal (from Greek μέταλλον ''métallon'', "mine, quarry, metal") is a material that, when freshly prepared, polished, or fractured, shows a lustrous appearance, and conducts electricity and heat relatively well. Metals are typicall ...

s for growing),

compact fluorescent lamp A compact fluorescent lamp (CFL), also called compact fluorescent light, energy-saving light and compact fluorescent tube, is a fluorescent lamp designed to replace an incandescent light bulb; some types fit into light fixtures designed for inca ...

s, and traditional

fluorescent lamp A fluorescent lamp, or fluorescent tube, is a low-pressure mercury-vapor gas-discharge lamp that uses fluorescence to produce visible light. An electric current in the gas excites mercury vapor, which produces short-wave ultraviolet lig ...

s. Full spectrum indoor LED grow lights are becoming more common in grow rooms due to their low energy requirements and very low heat output.

Luminous efficacy

Light is the essential "plant food"; everything else provided in cultivating a plant serves the purpose of helping it absorb and use the light. As the plant grows larger, it requires an increasing amount of light. There is no substitute for light: if the amount of light received by the plant is insufficient, the plant will stretch, and / or growth will slow to a halt. For indoor gardening, one of the most important requirements is the amount of light energy striking the surface of the plant ("incident light"), which can be measured in '' lux'' (lux = lumens / area illuminated in square metres). For indoor use, higher lighting efficiency produces more lumens per unit of area with less power and less waste heat. LED grow lights use very low power and are usually engineered to produce monochromatic light matching the highest absorption wavelengths of plant photosynthetic reactions. This design optimizes photosynthesis for a given quantity of input power, as opposed to fluorescent lights which only provide a portion of the desirable spectrum or incandescent and gas-discharge bulbs which also produce only a portion of the optimal wavelengths and, in addition, waste significant energy in the form of heat.

Light-emitting diode A light-emitting diode (LED) is a semiconductor device that emits light when current flows through it. Electrons in the semiconductor recombine with electron holes, releasing energy in the form of photons. The color of the light (cor ...

(LED) lamps have replaced high-intensity discharge lamps (HID) as the most efficient devices in terms of

Lumen (unit) The lumen (symbol: lm) is the unit of luminous flux, a measure of the total quantity of visible light emitted by a source per unit of time, in the International System of Units (SI). Luminous flux differs from power (radiant flux) in that radiant ...

s of light output per unit of

input, but are not yet as widely used. Continuing improvements in lifetime cost per lumen, long life power supplies, and banked or multi-LED fixtures are making LED lights more suitable for large-scale plant lighting. Compact fluorescent lamps are less efficient than LED or HID lamps, but run relatively cool and are widely available in simple fixtures and therefore continue to be used. Traditional fluorescent lamps generally do not produce enough concentrated light to be a primary light source for most indoor growing operations. Fluorescent and compact fluorescent lamps are excellent light sources for young plants (seedlings). They are also used to supplement the light generated by primary HID lamps.

Ventilation

As a controlled environment, grow rooms offer many advantages over outdoor alternatives. However, without adequate ventilation, the plants may consume resources, like

oxygen Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as wel ...

and

carbon dioxide Carbon dioxide (chemical formula ) is a chemical compound made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It is found in the gas state at room temperature. In the air, carbon dioxide is transpar ...

, faster than they can be replenished. Adequate gas exchange is necessary for optimal plant growth. Ventilation is also an important method for maintaining an optimal temperature for plant growth. Advanced grow room even include air conditioning to keep running temperatures down, as well as to boost the plant's growth rate.

Clandestine usage

Cultivating

marijuana Cannabis, also known as marijuana among other names, is a psychoactive drug from the cannabis plant. Native to Central or South Asia, the cannabis plant has been used as a drug for both recreational and entheogenic purposes and in various tra ...

is illegal in many countries, and thus some choose to grow marijuana indoors in an attempt to conceal their activities.

Law enforcement Law enforcement is the activity of some members of government who act in an organized manner to enforce the law by discovering, deterring, rehabilitating, or punishing people who violate the rules and norms governing that society. The term en ...

authorities attempting to locate grow rooms are known to search the records of electricity providers for signs of excessive electrical consumption and employ air or ground vehicles using

thermal imaging Infrared thermography (IRT), thermal video and/or thermal imaging, is a process where a thermal camera captures and creates an image of an object by using infrared radiation emitted from the object in a process, which are examples of infrared i ...

cameras/

FLIR Forward-looking infrared (FLIR) cameras, typically used on military and civilian aircraft, use a thermographic camera that senses infrared radiation. The sensors installed in forward-looking infrared cameras, as well as those of other thermal ...

infrared cameras Infrared (IR), sometimes called infrared light, is electromagnetic radiation (EMR) with wavelengths longer than those of visible light. It is therefore invisible to the human eye. IR is generally understood to encompass wavelengths from around ...

) to detect unusual instances of excess heat radiating or otherwise escaping from buildings. Growers respond to the use of thermal imaging cameras by isolating and decoupling rooms physically from the outer walls of buildings, and directing ventilation exhaust into a chimney.

References