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DEA-DEN-DIR-041-16

June 2016

Residential Marijuana Grows 

in Colorado: The New Meth 

Houses?

DEA 

Intelligence 

Report
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Residential Marijuana Grows in Colorado: The New Meth Houses?

Executive Summary 

Colorado’s state laws legalizing marijuana do not limit how much marijuana can be grown within a private 

residence. Further, there is no mechanism at the state-level to document or regulate home grows, even 

large ones. This has led to a proliferation of large-scale marijuana grow operations in hundreds of homes 

throughout the state. Much of the marijuana produced in large home grows is shipped out of Colorado and 

sold in markets where it commands a high price.

Although growing a large number of marijuana plants within private residences can fall within the parameters of 

state law, it presents potential risk to the occupants, homeowners, and neighbors of these residences, as well 

as to first responders who are called to them. Marijuana grows often cause extensive damage to the houses 

where they are maintained and are increasingly the causes of house fires, blown electrical transformers, and 

environmental damage. Much like the “meth houses” of the 1990s, many of these homes may ultimately be 

rendered uninhabitable.

Details

Colorado’s legalization of medical marijuana and recreational marijuana by voter referendum set the stage 

for unfettered marijuana production in the state. Both Amendment 20 and Amendment 64 contain loopholes 

that allow for large marijuana grows within private residences. Although the State of Colorado created the 

Marijuana Enforcement Division (MED)—a regulatory body for licensed marijuana businesses—the MED does 

not have authority to regulate home grows.

Access to medical marijuana became every Coloradan’s constitutional 

right in November 2000 when voters approved Amendment 20. 

Amendment 20 allows patients to possess six marijuana plants, unless a 

physician recommends more. As of 2016, physician recommendations 

for 75 to 99 plants are commonly used to justify large residential grows, 

many of which produce marijuana for sale outside the state. In January 

2016, there were 107,798 medical marijuana registry patients. Of those, 

roughly 8 percent (8,210 patients) had physician recommendations for 50 

to 99 plants.1

 Notably, in January 2014, when cultivation and possession 

of recreational marijuana became legal under state law, there were more 

overall medical marijuana patients (110,979), but fewer with elevated 

plant counts of 50 or more plants (5,308).2

As of March 2016, there is not a state-imposed limit on either the number 

of plants a physician may recommend for a medical marijuana patient 

or on the number of plants a patient may grow in a private residence. In 

May 2015, state legislation was passed that limited medical marijuana patients to growing 99 plants on private 

property—it will take effect January 2017.3

Amendment 64 allows any adult 21 years old or older in Colorado to cultivate up to six plants. 

It further allows for the possession of all marijuana produced by those plants, provided the marijuana remains 

in the enclosed residence and is not sold.4

 Amendment 64 also allows any adult in Colorado to “assist” any 

other adult in Colorado in “possessing, growing, processing, or transporting” his/her marijuana.5

 Consequently, 

large grows and/or quantities of processed marijuana within a residence are often justified through the claim 

According to the Colorado 

Department of Public Health 

and Environment, in January 

2016 there were 8,210 medical 

marijuana patients in Colorado 

with physician recommendations 

to grow 50 to 99 plants. If each 

patient grew 50 plants, that 

equals 410,000 marijuana plants.

From each plant, they would 

likely harvest 1 pound of finished 

marijuana every 90 days. That is 

1.64 million pounds of harvested 

marijuana per year.
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Residential Marijuana Grows in Colorado: The New Meth Houses?

that the resident is assisting others by 

growing or storing their marijuana. As there 

is no mechanism at the state or local level to 

document or regulate recreational marijuana 

home grows, there is no practical means for 

local police to verify whose plants are grown 

or whose marijuana is stored in any given 

residence. 

Some local governments have begun to place 

limits on the number of plants that can be 

grown in private residences. However, such 

local ordinances are widely varied and rarely 

effectively enforced.

As a result of the permissiveness of 

Colorado’s medical and recreational 

marijuana laws, the system is extensively 

exploited by traffickers who operate large 

marijuana grows that supply out-of-state 

markets. Since 2014, there has been a 

noticeable increase in organized networks of 

sophisticated residential grows in Colorado 

that are orchestrated and operated by drug 

trafficking organizations. These organizations 

operate hundreds of large-scale home grows 

throughout Colorado. Harvested marijuana is 

shipped or transported from Colorado to markets in the Midwest and along the 

East Coast.6

Indoor marijuana plants can grow as tall as 6 feet or more and yield more than a pound of harvested marijuana 

every 90 days. Growing them requires specific conditions that consume high levels of electrical power 

and water and results in the drainage of chemical-laden waste water. Grow rooms must be maintained at 

temperatures between 71 and 80 degrees Fahrenheit. At certain times during the growing cycle, plants must 

remain under high-power grow lights for 24 hours a day. Fertilizers and pesticides—sometimes harsh ones—

are required to grow robust and healthy plants. At times in the growing cycle, each plant can require 3 or more 

gallons of water per day. 

Local police departments often receive numerous calls from neighbors about marijuana grow houses. 

Common complaints include strong odors, excessive noise from industrial air-conditioning units, blown 

electrical transformers, and heavy vehicle traffic.

Colorado homes where marijuana is grown often sustain extensive structural damage. Moisture, 

condensation, and molds spread throughout the residence. Growers often cut holes in floors and exterior walls 

in order to install ventilation tubes. Growers often tamper with electrical systems in order to supply multiple 

high-power grow lights and industrial air-conditioning units. These alterations are often done by tenant growers 

with little regard for fire risk or the home’s structural integrity. This is an increasing concern for first responders. 

Figure 1. a Basement grow in a ColoraDo Home.

Source: DEA
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Residential Marijuana Grows in Colorado: The New Meth Houses?

Altered electrical systems with loose and 

entangled wires, flammable fertilizers and 

chemicals, explosive materials such as 

propane and butane, or holes cut into subfloors for venting all pose clear hazards to 

firefighters or police officers responding to 

the residence in an emergency situation. 

Outlook

Adding to the list of unintended 

consequences of marijuana legalization 

in Colorado, the proliferation of large 

residential grows is taxing local police and 

fire departments, consuming power and 

water resources, and potentially affecting 

home values in communities throughout 

the state. Further, the ability to establish 

large-scale marijuana grow operations 

within residential homes under the guise 

of state law will likely continue to attract 

drug traffickers and criminal organizations. 

Thus, Colorado will continue to be a source 

for much of the marijuana destined for 

markets in other states.

Figure 2. Do-it-YourselF Ventilation in a

ColoraDo grow House

Source: DEA

1 Colorado Department of Public Health and Environment, January 2016.

2 Ibid.

3 Colorado Senate Bill 15-014, passed May 2015.

4 Colorado Constitution. Article 18, Section 16, Subsection 3(b).

5 Colorado Constitution. Article 18, Section 16, Subsection 3(e).

6 DEA Denver Division Investigative Reporting. 2016; extracted information is: (U); overall document classification is: (U).

This product was prepared by the DEA Denver Division. Comments and questions may be 

addressed to the Chief, Analysis and Production Section at dea.onsi@usdoj.gov.