Indoor growing operations appear to be the most productive and secure for marijuana, Smith said.
"But we could have outdoor grows in eastern Washington," he said.
Since no state had previously legalized marijuana possession, Washington must invent a production system from the ground up, Smith said. Colorado did have a licensed system for growing medical marijuana, but that was very tightly regulated and probably more stringent than Washington needs, Smith said.
"We don't need to get to the level of oversight Colorado has in medical marijuana," he said.
Washington's new law decriminalizes possession of up to an ounce of pot for people over 21. But selling marijuana remains illegal for now. The initiative gave the state a year to come up with a system of state-licensed growers, processors and retail stores, with the marijuana taxed 25 percent at each stage.
In Colorado, a 24-member task force began work on pot regulations this week. The state's Department of Revenue must adopt the regulations by July, with sales possible by year's end.