In my early 20s, I worked briefly as an assistant manager in a medical marijuana dispensary in California. Growers would deliver massive sacks of weed each morning to the back door, and we'd haul the bags to an upstairs office for inventory purposes. One of my jobs, it turned out, was making up names for the different types of pot.

People talk up the hallowed pedigree of various marijuana strains. There's stoner lore about how one strain is stronger, how another makes you happy, how one's got a "really mellow vibe" or is "good for sleep." And some strains are legit examples of unique varieties with signature chemical compositions that you can trace to their origins (classics like White Widow or Blueberry). But a lot of names? They're totally fabricated. My job, I'm sure like managers in other medical pot clinics, was to make up these names as a marketing ploy. I called them Einstein, Alligator, Beethoven, Plato—any name I'd think could sell. If the name worked and we sold out of that type of pot? We'd find another type of pot and call it the same name. And this was a medical marijuana dispensary! So you know this shit happens all the time on the street. Long story short: In an unregulated market, the name of the pot you're buying is probably meaningless. The place you buy it doesn't guarantee its provenance. You never know what you're getting from one bag to the next.

But now?

I bought some excellent pot on July 8 at Cannabis City, Seattle's first legal retail cannabis store, just after it opened at noon. (Surprisingly for a pot store, it opened on time.) What legalization provides at Cannabis City, prohibition never could—certainty about what I purchased, what it contains, what it doesn't contain, where it came from, and where the money goes.

The glut of information on the labels affixed to all pot now sold legally in Washington State, per the law, represents something between government overreach and a pot lover's dream come true.

The label begins by detailing the precise composition of the drug. The strain I bought is called OG's Pearl, which contains exactly 21.5 percent THC (the predominant set of psychoactive chemicals in cannabis). The label then lists the CBD and CBG, two other compounds. The label goes on: My buds were 80 percent indica-type cannabis (as opposed to the more stimulating sativa). It lists the moisture content (6.52 percent), the day it was harvested (June 2), the day it was tested (June 23), where it was grown (Kitsap County), how it was grown (indoors), and who grew it (Nine Point Growth Industries).

Consumers will decide whether all that certainty is worth the price; the two-gram bag was $40 (including $10 in tax), which is generally higher than street prices.

Some people say it's not worth it. Standing beyond the media frenzy of cameras outside Cannabis City was John Stuart, 24, who was wearing a pair of pot-leaf-print shorts and a Marilyn Manson T-shirt. His friend had a white pit bull on a rope. Were they waiting to buy pot inside? "No, because I got a medical marijuana card and it's way too expensive at Cannabis City," said Stuart. "You could go to Westlake Park and get it for $10 a gram. That's a lot cheaper than going to the store."

But if Mr. Stuart buys pot in the park, he'll likely have no idea what he's really getting (or where his money goes). And some dispensaries, but not all, will lie through their teeth about what they're selling. I know this because it was once my job to tell that lie.

The chunk of vegetation I took home, like all the pot legally sold in Washington, was tracked from the time it was a baby clone to a full-grown plant, then tracked from harvest and into this package. And because it is so closely monitored, consumers have unprecedented certainty that it's not tainted with other drugs, sketchy fertilizers, tobacco juice, mold, soap, etc. It's also a guaranteed weight—you're not going to get shorted on your deal. And you know your money is paying for legit in-state jobs and not funding some murderous interstate cartel.

The question is: Do we have enough legal pot to keep this system running?

As we reported last week, part of the reason prices are so high is that the Washington State Liquor Control Board, which made many of the rules for cannabis sales after voters legalized pot in 2012, created onerous regulations for retail outlets and growers. As a result, the state has issued licenses to only 24 of the 334 pot stores that are supposed to open. Even worse, the liquor board has licensed only enough grow space for 8 percent of the total pot market. That leads to artificial scarcity and high prices.

Cannabis City ran out of pot after three days, reflecting a trend among pot stores, and it doesn't expect more pot until July 21.

Alison Holcomb, who sponsored the initiative that legalized marijuana, said it was important to license enough growers. "It is critical that we can sustain stores, instead of seeing them going under due to lack of product to sell to customers," she said. The liquor board and state legislature can and should take action to grease the wheels of the aboveboard cannabis market.

Until then, this information on the labels—and the state's campaign to educate people about cannabis—represents the end of "Just Say No" in our state. That was an era of the government lying about the harms of pot and promising you that one toke led to a lifetime of addiction, while pro-pot forces generally exaggerated benefits and downplayed risks. More and more, both sides are settling on facts and providing information—sometimes more than you know what to do with, right on the label—for users to make up their own minds.

And even if it costs a few bucks more per gram until the market smooths out, it's worth it.