Marijuana Grow Houses are normal houses in residential areas that are converted for the purposes of growing marijuana. Larger houses are often used because of they provide a larger capacity for growing marijuana, but such operations may be found in any home, in any neighbourhood.

To make a house suitable for cultivating marijuana, significant changes are made to the home's structure. High intensity lighting is needed to grow the plants (which is costly), so many home grow operations by-pass the electricity illegally putting the neighbourhood at risk of fire and electrocution. Combined with construction to provide water and ventilation for the grow operation, the house becomes uninhabitable for future residents. Unless major repairs are made, the house is ruined and the property value of other homes in the area is lowered.

Marijuana Grow Houses often have links to criminal elements and organized crime. Individuals associated with grow operations have been found to carry weapons and may be considered dangerous. Also, there is a risk of increased violence and residual crime in neighbourhoods associated with illegal activity. Marijuana Grow Houses are not only a police concern they are a Public Safety Issue!!!!

• POISONOUS FUMES – noxious fumes from the growing operation can build up inside a Marijuana Grow House, or be vented from it. Mold and fungus from condensation can accumulate inside the growing operation, creating a health hazard. Gases from chemicals used in the growing operation can also build up inside the house, or vented outside (which effect neighbouring homes).
• FIRES – electricity is bypassed, so that it is diverted from neighbouring homes. This increases the chance of fires starting due to the amateur rewiring jobs.
• ELECTROCUTION – people inexperienced with rewiring electrical systems may electrocute themselves, or people exposed to the wiring may be electrocuted. People can also be shocked by the electricity bypasses charging the ground itself.
• VIOLENCE – to protect distribution and production of marijuana, those involved in a growing operation may be armed with weapons, and have been known to carry out assaults or homicides. Criminal elements attracted to the area to purchase the marijuana may also be armed and violent, or commit residual crimes.
• INCREASED CRIME – Marijuana from home grow operations are sold to children and other members of the community. The money raised from these sales are used to fund organized crime. In their 2002 Special Report, the Canadian Intelligence Service Canada stated that "the Hells Angels and Asian-based organized crime groups, particularly Vietnamese-based groups, continue to be extensively involved in the large-scale cultivation and exportation of marihuana."
• BOOBY TRAPS - traps may be set by growers to protect their product from unauthorized persons entering the home or property. These traps can be life threatening, and expose emergency responders (and others entering the property) to hazardous conditions.
• POWER OUTAGES – the rewired electrical systems can become overloaded, and may even cause hydro transformers to blow
• HIGHER UTILITY COSTS – the cultivation of marijuana requires large amounts of water and electricity, so utilities are tampered with and redirected from neighbouring sources. By stealing the utilities, the costs of growing the marijuana are lowered. However, this theft leads to higher utility bills.
• STRUCTURAL DAMAGE – houses are modified to suit the growing operation, damage may be caused from the construction or the cultivation of marijuana. Extensive repairs are required to make the house habitable after the growing operation has been shut down.
• ENVIRONMENTAL DAMAGE - chemicals used in the grow operation are improperly disposed of, draining into the ground and water system.
• HAZARD TO CHILDREN - Children in the neighbourhood are exposed to the dangers mentioned above, and may be sold marijuana. Police have also found children living or brought by their parents to the grow houses, exposing them to these hazards.

There are a number of factors that may indicate the presence of a Marijuana Home Grow Operation in your neighbourhood. These include:

• Residents rarely appear to be at home, and attend the house for brief periods of time (such as a few hours) before leaving. Despite this, radios or televisions may be left on all night, making it sound as if someone is there.
• Visitors behave strangely or visit at odd hours
• Entry to the home is often made through the garage or side/back entrance, to conceal activities.
• Windows are boarded or covered up, preventing light from entering the house and concealing activities inside. Bright lights may be seen escaping from windows, and the windows may have a layer of condensation on them. Even though the windows are always closed, air conditioners never run.
• Equipment used in the growing operation (such as large fans, lights, plastic plant containers and other items) are carried into the home.
• Sounds of construction or electrical humming from equipment may be heard
• Hydro meters are tampered with, and there are signs of digging or disturbance around the outside hydro box. There may be localized surges and decreases in power.
• Strange odours are coming from the house. Marijuana growing in the house will produce a strong, skunk-like odour that you may be able to smell from outside the house.
• Exterior appearance of the property is untidy. There is little outside maintenance done (unshovelled snow, uncut grass, etc.), and garbage bags containing used soil and plant material may be disgarded in areas surrounding the house. Mail delivered to the house may be left unchecked, so that flyers and junk mail pile up in the mailbox.
• Warning signs are posted in windows or around the outside of the house. These may warn people to "Beware of Dog" or that "Guard Dogs" are on the property.

In 2002, the Morality Unit and Street Crime Unit targeted commercial marijuana grow operations in the Niagara Region, dismantling fifty of these illegal labs. These operations were located in dense residential areas, to disguise the grow operations as normal family homes. A majority of these houses were converted for the exclusive purpose of growing high grade marijuana that is being exported to the American Market at an increased profit. The estimated value of the thousands of marijuana plants and equipment seized in these operations were in the millions of dollars.