Oregon public health officials this week drafted new rules for how many plants medical marijuana cardholders may grow at home or at a grow site registered with the state.

The regulations are the result of legislation passed this year to tackle the flow of medical marijuana into the black market.

The bottom line for medical marijuana patients: A residence, no matter how many people live there, may have no more than a dozen mature plants -- and that includes recreational ones.

Here's how the new guidelines break down for patients and grow sites:

Patients growing for themselves at their residence:

Patients and their caregivers may possess a total of six mature plants and a dozen immature plants. Those limits include any plants they opt to grow under the state's recreational marijuana law. Under state law, households may grow up to four plants for recreational purposes.

The law does not define the size of immature plants in this scenario.

A residence may have no more than a dozen mature plants and two dozen immature plants. That limit includes recreational plants.

Grow sites in residential neighborhoods in cities:

May have a maximum of 12 mature plants

24 immature plants over 24 inches high

Unlimited number of immature plants less than 24 inches high

Grow sites outside of cities and residential areas:

May have a maximum of 48 mature plants

96 immature plants over 24 inches high

Unlimited number of immature plants less than 24 inches high

The state has grandfathered into the system grow sites that have continuously operated since Jan. 1, 2015.

Grandfathered grow sites within city limits and residential areas:

May have a maximum of 12-24 mature plants

48 immature plants over 24 inches high

Unlimited number of immature plants less than 24 inches high

Grandfathered grow sites outside of city limits and residential areas:

May have a maximum of 48-96 mature plants

192 immature plants over 24 inches high

Unlimited number of immature plants less than 24 inches high

The maximum number of plants for these sites is based on how many patients have been continuously served by the grow site since 2015.

-- Noelle Crombie

503-276-7184; @noellecrombie