Fact and fiction about home grow marijuana

Senate President Stanley Rosenberg and other leaders recently signaled the state legislature’s intent to revise many aspects of the marijuana legalization law passed by voters last November. Rosenberg pointed to the new law’s home grow provisions as one target, calling the six-plant per person, 12-plant per household allowance a “very large quantity.”

Rosenberg’s comments echo statements made by Question 4 opponents like the Massachusetts Municipal Association. Home grow allowances are too lenient and too difficult to monitor, they say. They have trotted out alarming scenarios of 12-plant home grows leading to huge illegal sales operations.

Rosenberg and his fellow legislators would be wise to reject these hysterical arguments and base their deliberations on reality and facts. By doing so they will find that the new law’s home grow allowances are thoughtful and reasonable. In fact, the Mass home grow allowances fall in the middle of allowances in other legal states.

Consider the details of growing marijuana in a home. A viable plant is generally defined as 12 inches tall. Anything smaller is considered a seedling/clone and not yet a viable plant. Home grow opponents often overlook the time between planting the seed and harvesting the flower. From planting to smoking takes five to six months. Growers can perhaps shave five weeks off of by using clone-cutting, but even then there’s four months before the harvest, followed by a few weeks of drying and curing.

The size of an indoor plant is restricted by usable space. A home with eight-foot ceilings actually provides only four or five vertical feet for growing. The bulk of production comes from the top 12 inches of the plant. Unlike an outdoor grow, an indoor grow has lights hung directly overhead. At best the plants may get some noon sun. There is no arc of the sun’s movement across the sky to stimulate the lower branches for any significant growth. Ultimately, production is limited to the square footage of the canopy of the plant.

For that reason, some growers use a method called “scrogging,” where a plant is manipulated and bent in order to force it to grow out horizontally. This increases yield by exposing all producible branch space to light nourishment. However, these scrogged plants take months longer to grow and use three times the square footage of vertically-grown plants.

The vast majority of home growers will achieve about three harvests a year. Growers can stagger the plants into varying stages of growth to achieve more harvests, but they are then harvesting fewer plants. Ultimately, production is limited to what 12 plants can produce in one cycle.

So how much can one expect to yield in a typical home grow? Assuming a grower has the expertise and space to grow 12 scrogged plants they would see a yield of roughly four ounces per plant. Three such harvests a year averages out to about 2.75 ounces per week for two adults.

But most growers are going to grow vertically. This method yields much less weight. One can expect around two ounces at most from a vertically-grown plant. That amounts to about 72 ounces a year, which averages about 1.3 ounces a week for two adults. These are not unreasonable amounts when averaged out over the course of the year.

This is hardly the type of operation that would fuel an illicit market, or yield 30 joints a day, as Rosenberg claims to have been told by “people who know a lot more about this than I do.” And it doesn’t approach the absurd 300-ounce annual yield projected by the Massachusetts Municipal Association.

Home grow is important for many reasons. It prevents monopoly. It provides industry innovation. It allows adults to indulge in a hobby similar to brewing their own beer or wine. It brings new genetics and products.

And, it is what the voters voted for. Beacon Hill needs to respect that.

Peter is the president and director of the Massachusetts Grower Advocacy Council.