Oregon adults will be able to purchase limited amounts of marijuana starting Oct. 1 -- three months after possession became legal -- under a bill that won final legislative approval on Thursday.

The House approved the temporary "early sales" program on a 40-19 vote and sent it to Gov. Kate Brown for her signature. If she signs the bill, Oregon will have the quickest retail start for any of the four states that have legalized recreational use of the drug.

In Colorado and Washington, the first two states to legalize marijuana, retail sales didn't start until at least a year after possession became legal. In Alaska, legal possession started in late February but retail sales aren't expected to start until 2016.

Backers of Senate Bill 460 said they wanted retail sales to start as soon as possible to keep newly legal consumers from turning to the black market. Possession became legal on Wednesday and people 21 and older are now allowed to have up to one ounce in public or eight ounces at home, and they can grow up to four plants.

Under SB 460, medical marijuana dispensaries will for the first time be allowed to sell to adults who don't have a medical marijuana card. However, these recreational consumers would be limited in what they could buy.

Dispensaries could sell up to one-quarter ounce of dried marijuana to a recreational consumer per day, as well as seeds and up to four immature plants. They won't be allowed to buy extracts, cannabis-infused edibles and a wide range of other products available to medical marijuana patients.

Pressure for some kind of temporary sales program grew after the Oregon Liquor Control Commission said it would not be ready to license retailers for recreational sales until the latter half of 2016.

With such a long lag time, "we incentivize the black market it we leave this unaddressed," said Rep. Andy Olson, R-Albany.

The number of dispensaries around the state has grown rapidly since the state started licensing them a year ago. Much of the growth comes from investors planning to shift over to exclusively serving recreational users once the OLCC starts licensing retailers. In the meantime, many dispensary owners pushed legislators to allow the early sales, saying it would be an economic lifeline for them.

Cities and counties would have the power to prohibit early sales at the dispensaries -- and many communities have already taken steps to keep out dispensaries altogether.

The Oregon Health Authority has issued more than 300 permits for dispensaries around the state, and some 270 are in operation.

Under a separate measure that has also been sent to the governor, House Bill 2041, there will be a 25 percent tax on marijuana sold under the temporary program.

However, the tax won't start until Jan. 4, opening the window for tax-free cannabis shopping in the last three months of the year.

"We are giving recreational users another reason to stop going to the black market," said Olson.

The measure was opposed by 17 Republicans and two Democrats.

--Jeff Mapes

503-221-8209

@jeffmapes