Officials said they adopted the rule to undercut illegal dealers and set the stage to license an industry that has more than 300 retail stores selling the drug for recreational use, The Seattle Times reported Wednesday.
The board's action "just built the template for responsible legalization of marijuana," said Alison Holcomb, author of the law that legalized sale of the drug in Washington.
The 43-page rule may still require some tweaking, but board member Chris Marr said the agency would be "excellent position" to open stores by the middle of 2014.
Potential customers won't be able to sample the product under the new rules, but they will be able to smell it through screened containers.
Packaging will have to be childproof and bear warning labels that marijuana is intoxicating and can be habit-forming. It also will show potency as measures in percentage of THC, the primary psychoactive ingredient in the herb.
Stores will only be able to stock products with safe levels of toxins such as pesticides, bacteria and metals.
The market, not the liquor board, will determine prices.
The rule favors indoor growers, limiting farms to no more than 30,000 square feet.
Randy Simmons, the state marijuana project director, said demand is estimated at 80 metric tons next year.
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