Often simple camouflage techniques can avert detection, such as mixing cannabis plants with other bushy, leafy species. Plants started outdoors late in the season do not grow as tall, attracting less attention when placed next to plants of similar or taller stature.

A common technique used by many outdoor growers is to dig a hole and put a potted plant in it. This can reduce a plant's height by at least a foot, reducing visibility to neighbours, visitors and guests. Also, some growers top the plant when it is only 12 inches (30 cm) high, and grow the 2 tops horizontally along a trellis. When using this technique, it is unlikely the plant will grow to be over 3 feet (1 m) tall.

Law enforcement agencies often monitor certain wider areas, particularly areas of countryside with a significant history of outdoor cannabis cultivation. In helicopters, they use infrared cameras and other equipment that can detect cannabis by measuring the heat and reflective signature of the vegetation below. Cannabis has higher reflectivity at certain wavelengths than other rural crops, such as corn. Law enforcement agencies have found that the use of this technology has become necessary in their detection efforts because many growers hide cannabis among other plants, making detection with the naked eye difficult even from the air. These techniques are effective and difficult to defeat because a plant's reflective signature is difficult to change or mask. It has been said that if the cannabis plant is planted by a pine or cedar tree the heat from the tree will overlap the cannabis plant heat making it harder to detect from helicopters.

Modern Grow-Op detection utilizes a sensor arsenal, which includes the FLIR (Forward-Looking Infra-Red) system. This well known system detects the Infra-red signatures of high heat sources, associated with the metal-hydride lights used in large grow operations.

  In order to avoid being detected it is best practice to use thermal paints on the outside and inside of buildings, to reduce the outgoing thermal energies. In addition, the use of mylar tarps, or tarp-backed survival blankets, will further reduce the thermal output of your grow op.


All objects with a temperature above absolute zero emit infrared radiation. The hotter an object gets the more infrared radiation it emits. These emissions cannot be seen with the naked eye. However, a thermal imager can detect infrared radiation emitted from an object and convert its readings into a two-dimensional, black-and-white picture.

The picture contains various shades of gray, depending upon how much infrared radiation the object is emitting. The hotter areas emit larger amounts of infrared radiation and are lighter in color; the cooler areas appear darker. The device does not measure the actual temperature of its target; it only detects the relative temperatures of different areas of the object. A thermal imager is extremely sensitive and reportedly can detect temperature variations as small as 0.1 degrees centigrade. The images created by the device can be projected onto a small viewing screen or preserved on video- tape or photographs. The thermal imager is small enough to be hand- held, but often is mounted under a helicopter and flown over its target.

The technology is not new. The military has used it for years on the battlefield. Law enforcement has adopted the device only recently, using it in search and rescue operations, fugitive apprehensions, and along the border to detect drug smugglers and illegal border crossings. Moreover, thermal imagers have been particularly helpful, albeit controversial, in the detection of indoor marijuana-growing operations.


 Police will fly at an altitude between 1,200 and 1,500 feet in a helicopter fitted with FLIR. The thermal image of a structure will show the walls and other areas as bright white, indicating significant heat was escaping. This is than determined by the FLIR operator as being consistent with that of a structure being used for an indoor marijuana-growing operation.

 In a court case (in the USA), one grow operation was busted with the method above, and while in court they argued that the FLIR system was used against their rights under the Fourth Amendment.

Fourth Amendment: 'The right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures, shall not be violated, and no Warrants shall issue, but upon probable cause, supported by Oath or affirmation, and particularly describing the place to be searched, and the persons or things to be seized.'

The district court concluded that the defendants had no subjective or actual expectation of privacy in the area scanned by the police with the FLIR. The court said that FLIR is limited to "detecting differences in temperature on the surface of the object being observed," and "did no more than gauge and reflect the amount of heat that emanated" from the defendants' house. In other words, the FLIR registered only heat escaping from the defendants' house. The court described this escaping heat as waste heat, or "abandoned heat," because the defendants had not tried to prevent its escape. Indeed, they used fans to vent the heat to the outside, voluntarily exposing it to the public. They never attempted "to impede its escape or exercise dominion over it." Under these circumstances, the court concluded that the defendants did not have an actual or subjective expectation of privacy in the waste heat.

 If anything can be learned from this case, it is that you must actually make the effort to mask your signature and heat emissions; otherwise the police will be able to scan your structures with impunity (exemption from punishment or loss). If you’re an American grow operator, and you make the effort to mask your heat emissions, you can try to claim protection under the Fourth Amendment.


 On the modern battlefield, 70% of weapon systems worldwide use electro-optic or Infra-Red technology it is fundamental to realize the danger of thermal radiation and how to implement IR concealment.

There are several methods of creating an infra-red mask, One of the most basic way is the use of Mylar or Aluminized "Space blankets". A space blanket is made of a laminated thin layer plastic film with a metallic coating. A major step up from the space blanket, which is a military specification casualty/Survival blanket. These are similar to the space blanket, but have a tarpaulin backing, which improves its insulation and durability. The use of blankets are somewhat limiting and can be expensive over a relatively large structure.

Another method is the use of Infra-Red Camouflage paint or variable emissivity paints. These are usually uniquely made for military applications and not sold to the general public, but a suitable replacement technology is ceramic insulating paint. This paint is designed for homes and is made to reduce heat emission of a structure to reduce power bills. Normally, the ceramic insulation comes in the form of micro beeds or spheres to form a matrix within the paint, and can be purchased as an additive to medium quality paints. This paint should than be applied to both sides of walls, and roof structure, to ensure maximum protection.

The method of masking is very important as a very basic form of protection against Infrared detection. It should be noted that the understanding of heat flow, can truly benefit the total reduction of heat that is detectable. Consider the concept of absorbing heat and exhaust from plant production, and venting them via long underground pipes such as a sewer pipes.


Modern schools are no longer about education, but about drug detection. As one American principle said "The School needs to know if a kid is doing drugs". Marijuana is especially bad because people that utilize it begin to be creative and bored from their brainwashing. In a study conducted in 2003, by the University of Michigan and the National Institute on Drug Abuse showed that drug testing actually increased the likelihood of students doing drugs. According to the study, 21% of students did drugs while the school was actively testing, compared with 19% in schools with no drug testing. 37% of seniors smoked marijuana in drug testing schools, and 36% in non-testing schools. With that said, there are no known studies on the effect of drug testing and the likelihood of civilians doing drugs, but the trend from educational systems is very apparent.

 With that said, let us look at methods that educators and police are utilizing in catching those marijuana users.


 After marijuana is smoked, chemical traces of Cannabinoids can be traced in a specimen of either urine, hair, blood or the oral cavity. Generally drug tests have intentionally high standards to avoid false positive results, to disprove the accidental ingestion of second-hand smoke. Some drug testing does not rely on Cannabinoid detection but the degrading of drugs into metabolites(small molecules or protein ligands), which can be detected as they try to excrete from the body.

 Urine tests are the least expensive method of testing and can be done by non-medical staff. Cannabinoids can be detected usually within 24 hours - 3 weeks after initial usage. Abstain from use prior to test can reduce the chance of detection. In addition, lack of fluid or temperature increases can reduce sample integrity.

Hair testing is rarely done as the results are not as reliable as urine tests, but it is considered to be the least intrusive method of drug testing. Currently hair testing is many times more expensive that urine tests, though can detect Cannabinoid use for 1-3 months. Usually, better at detecting long term use, verses usage in the last week. 

 Blood testing is considered the most intrusive method, as well as being the most expensive method. It is also the most accurate method, though is the least likely method of testing. Cannabinoids can be detected 6 hours after cannabis use, though after 22 hours Cannabinoids are not detectable.

 Oral cavity detection or Saliva testing is used to detect very recent use. Cannabinoid detection is usually only detectable for 4-24 hours, and is confined to detecting current intoxication only.

 Perspiration Testing is a way to monitor people on probation or parole. A patch must be worn on the skin, and as an individual excretes perspiration, Cannabinoids are detected on the patch, which is checked by law enforcement agencies.

 It is very important to note that drug testing will vary depending on the individual, as Cannabinoids react differently in individuals as well as people will have different metabolic rates, thus changing the length of time for detection considerably. For example a chronic smoker, who has a slow metabolism and large amount of body fat, will retain Cannabinoids for a longer time than that of a new user, with quick metabolism and with small amount of body fat. Obtain a THC Calculator to determine the likely period it would take to be clean.


 Dogs are trained to associate their favorite toy as having the smell of marijuana. The dog simply searches with their nose for their favorite toy, to detect marijuana. Police officers must follow their dog, to indentify where the drug was discovered, to assist in the prosecution of drug users.

The sense of smell is the detection of chemicals dissolved in air, and dogs have a olfactory acuity (smell detection) hundreds of times greater than humans. Hence armed with a desire to find their toy and the known smell of marijuana, dogs can easily detect marijuana.

 If a dog consumes marijuana such as inadvertently eating a stash of marijuana or via second-hand smoke, the dog will typically experience effects for 30-90 minutes. Cannabinoids will be stored in the dog’s body fat for a period of time (Use THC Calculator to estimate time). Attempts to induce vomiting are generally ineffective due to the nausea control properties of THC. Drinking Activated charcoal can help the detoxification process, as the charcoal will capture toxins and the patient will pass them. This is the normal method of treatment for any poisoning.


"The sense of smell is perhaps not as keen in humankind as in other animals, but some odors such as burned Cannabis are very strong and very distinctive. A person who is trained to recognize the odor of marijuana and is familiar with it and can recognize it has probable cause, based on the smell alone, to search a person or a vehicle for contraband. "(State v. T.T. [Fla.App.5 Dist. 1992] 594 So.2d 839.)


 Narcotic Residue Detection Aerosol Sprays allow an individual to detect marijuana with no additional tools. Training, in only seconds. Pure 4-Benzoylamino-2,5- iethoxybenzenediazonium Chloride Hemi[Zinc Chloride] Salt or Methylene Blue BB(Basic Blue 9 ) is used, though possibly modified for stability, in packaged into a aerosol delivery system. Once sprayed on objects in question, the spray will detect residue levels of less than 10 micrograms.


 Hyperspectral Optical Technology is a sensor system which

detects hundreds of "spectra" or measurements of reflected or emitted energy. Scanning many channels across a narrow bandwidth, the sensor system is able to provide detailed information on about target's spatial and spectral patterns. The system works by breaking the optical spectrum into as many as 30 unique colours at a rate of 30 times per second. The sensor quantifies the spectra energy in each image and then builds a filter which is "tuned" to the specific target. For specifically marijuana further processing is needed, but from an elevation of 5,000 feet or in horizontal position several hundred yards this sensor is able to detect marijuana. Even through heavy vegetation, it is able to differentiate between recreational cannabis and industrial cannabis, due to specific objects and substances having unique "spectral signatures". Natural, man-made objects, different vegetation and even various types of building material can be detected. In a high elevation it is able detect chemical or biological weapons, run bomb damage assessment of underground structures, and foliage penetration to detect troops and vehicles movement.


 In a Mississippi town called "A precious coin in the purse of the South.” named after a Spanish coin by the French inhabitants of New Orleans, Picayuna has one of the newest method of law enforcement. A Unmanned Aerial Vehicles or UAV is semi-autonomous robot which fly’s around and with the use of sensors spies on civilians. Air-O-Space teamed up with the Picayune Police Department to conducting information gathering and surveillance, or in other words used the UAVs to search for, locate, and videotape marijuana fields, in the name of the "War against Drugs". The use of UAVs is likely to become more apparent, especially in nations which police spy on their citizens.

"Mobile / Temporary Perimeters, Crowd Control, Reconnaissance: Deploy robots in rapid, coordinated fashion to form temporary perimeters for special events or VIP transportation. Define no-man zones quickly or address hostile crowds without risk of harm to personnel. Send robots into standoff situations or dangerous search environments to take a close-in look."




 With the use of the Ikonos high-resolution satellite, the Royal Canadian Mountain Police and Canadian Department of Defence teamed up in August 2000, and with an experimental approach attempted to tie in high-resolution satellite imagery, special geographic mapping techniques and other data to determine probable crop sites at early stages. Four sample sites in the southern Interior of British Columbia, Seymour Arm, Slocan Valley, Upper Kettle and Christina Lake proved to be difficult for the satellite to differentiate between the surrounding wetlands and the marijuana crops.

It was determined that the RCMP would go back to relying on traditional helicopter detection methods, citing the failure to detect marijuana in mixed crops, as well as the fact that majority of marijuana is grown indoors.  Paul Kennedy, a deputy Solicitor General's senior assistant, was quotes as saying”space-based method is more suited to the "large swaths of land" used to cultivate plants for cocaine and heroin production in countries like Bolivia and Colombia".

 In 1992, it was reported briefly in the news that the American federal government provided a grant for $643,500 to the Office of National Drug Control Policy (ONDCP) to detect both outdoor and indoor marijuana cultivation, with the use of a satellite. According to the report, the Santa Monica, California Sheriff's Department would team up with NASA's Jet Propulsion Laboratory to develop the system. According to the 2002 National Drug Control Strategy, the use of remote sensing would be run by the Department of Defence for the ONDCP, though further information of this project is classified.

Back to the TOP"