In instances where the local laws do not permit growing cannabis, cultivators may choose to grow in forests or rugged and rural areas where the local population are not likely to find the crop. Another technique is to grow cannabis in a crop that is larger and obscures the plants, such as maize. This is reported by the United States government to be common in the midwestern states. Bamboo and elderberry are also used as camouflage companion plants.
Some government organizations have claimed that in state and national parks, people have been injured by these "rebel farmers" protecting their crops, including a well documented developing problem with Mexican cartels growing cannabis in US national parks and forests.
Cannabis Buds are typically harvested when fully ripe. Generally, ripeness is defined as when the white pistils start to turn dark yellow, orange, light to mid red, etc. and the trichomes, "crystals", barely begin to turn milky from clear. These trichomes can range from completely clear (generally deemed underdeveloped), to amberish-red. Ideally, professionals will use a decent power magnifying glass, a brix meter (to measure "sugar" content), and a microscope. The potential seed pods swell with resins usually reserved for seed production, thus improving the quality of the buds (called colitas), which will swell to form full "colas". If harvested early on with only a few of the pistils turned color, the buds will have a more pure THC content and less of the cannabinoids CBD and CBN. The later, non-psychoactive cannabinoids contribute to create the bouquet of the marijuana, and modulate the overall nature of the high from anywhere from purely psychedelic to purely sedative.
Contrary to sinsemilla (bud production focused cultivation), seeds are harvested when fully developed and often after the accompanying buds have begun to deteriorate. In contrast, hemp grown for fiber is harvested before flowering, and cannabis grown for cloning is not flowered at all.
A recent method of curing is called water curing. This method is quicker and can improve a lower quality product. The buds are submersed in water for a period of 7 straight days, changing the water daily. The buds are then dried and are ready to use. Nutrients can be added to the plants up until they are harvested. When water curing, the water will flush out harmful chemicals (such as the ones used to feed the plants) as well as proteins, sugars, pigments and some resins. This will also increase the THC to weight ratio.
Tincture. Ethanol is used to extract cannabinoids from the marijuana plant (THC is soluble in alcohol). The extraction process takes longer, but results in an edible product. Marijuana stems, leaves and buds can all be used. The resulting mixture can be eaten straight, mixed with food or even smoked. Many smokers prefer to dip cigarettes in the mixture, which allows them to smoke in public without detection. Contact with direct flame causes this liquid to lose its THC content (THC vaporizes at 180°C). Smokers usually heat the liquid and inhale the vapors through a straw.
Hash Oil. Allowing the ethanol in a tincture to evaporate makes hash oil. **Ethanol should never be evaporated with direct heat, or near an open flame!** The resultant hash oil is often very strong in terms of THC content (depending on parent material), and can be then smoked. Delta 9 THC is most strongly soluble in petroleum ether and less so in ethanol. Adding petroleum ether to tincture will extract D9 THC, and leave water soluble chemicals in the ethanol (certain cannabinoids, proteins, chlorophyll, etc). Hash oil purified this way can exceed 90% D9 THC.
Outdoor cultivation is common in both rural and urban areas, with outdoor cultivators tending to grow Cannabis indica-based strains because they have heavy yields, quick maturing time, and tend to stay shorter than sativa strains. Some growers prefer sativa to indica because of its clear headed high, better response to sunlight, and lower odor emissions.
Cannabis plants blend in easily with other plants and are unidentifiable by all but the most observant. 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. Even tall plants grown among trees can be almost invisible in their camouflage.
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.The resin on the cannabis plant is what make it visible by infrared,dry conditions are what causes resin production.