CONCORD, N.H. — As promised, Gov. John Lynch has vetoed a bill that would legalize the home cultivation of marijuana for medical purposes.

The bill would allow patients with debilitating medical conditions or the patient’s designated caretaker to cultivate and possess up to six ounces of marijuana, four mature plants and 12 seedlings at a registered location. Lynch says that would lead to a virtually unlimited number of potential cultivation sites, making it impossible to control the distribution and prevent illegal use.

Lynch also vetoed a similar bill in 2009. The current bill passed both the House and Senate with wide margins, making it likely that the Legislature could override Lynch’s veto next week.