SPOKANE, Wash. — It may be called weed, but marijuana is legendarily hard to grow.

Now that the drug has been made legal in Washington and Colorado, growers face a dilemma. State-sanctioned gardening coaches can help folks cultivate tomatoes or zucchini, but both states have instructed them not to show people the best way to grow marijuana. The situation is similar in more than a dozen additional states that allow people to grow the drug with medical permission.

That’s leaving some would-be marijuana gardeners looking to the private sector for help raising the temperamental plant.

“We can’t go there,” said Brian Clark, a spokesman for Washington State University in Pullman, which runs the state’s extension services for gardening and agriculture. “It violates federal law, and we are a federally funded organization.”

The issue came up because people are starting to ask master gardeners for help in growing cannabis, Clark said. Master gardeners are volunteers who work through state university systems to provide horticultural tips in their communities.

The situation is the same in Colorado, where Colorado State University in Fort Collins recently added a marijuana policy to its extension office, warning that any employee who provides growing assistance acts outside the scope of his or her job and “assumes personal liability for such action.”

The growing predicament is just the latest quandary for these states that last year flouted federal drug law by removing criminal penalties for adults over 21 with small amounts of pot. In Washington, home-growing is banned, but it will be legal to grow pot commercially once state officials establish rules and regulations.

In Colorado, adults are allowed to grow up to six marijuana plants in their own homes, so long as they’re in a locked location out of public view.

At least two Colorado entrepreneurs are taking advantage of that aspect of the law; they’re offering growing classes that have attracted wannabe professional growers, current users looking to save money by growing their own pot and a few baby boomers who haven’t grown pot in decades and don’t feel comfortable going to a marijuana dispensary.

“We’ve been doing this on our own, but I wanted to learn to grow better,” said Ginger Grinder, a medical marijuana patient from Portales, N.M., who drove to Denver for a “Marijuana 101” class she saw advertised online.

Grinder, a stay-at-home mom who suffers from lupus and fibromyalgia, joined about 20 other students earlier this month for a daylong crash course in growing the finicky marijuana plant.

Taught in a rented room at a public university, the course had students practicing on tomato plants because pot is prohibited on campus. The group took notes on fertilizer and fancy hydroponic growing systems, and snipped pieces of tomato plants to practice cloning, a common practice for nascent pot growers to start raising weed from a “mother” marijuana plant.

Ted Smith, a longtime instructor at an indoor gardening shop, led the class, and warned these gardeners that their task won’t be easy. Marijuana is fickle, he said. It’s prone to mildews and molds, picky about temperature and pH level, intolerant to tap water.

A precise schedule is also a must, Smith warned, with set light and dark cycles and watering at the same time each day. Unlike many house plants, Smith warned, marijuana left alone for a long weekend can curl and die.

“Just like the military ... they need to know when they’re getting their water and chow,” Smith said of the plants.

The class was the brainchild of Matt Jones, a 24-year-old Web developer who wanted to get into the marijuana business without raising or selling it himself. As a teenager, Jones once tried to grow pot himself in empty Home Depot paint buckets. He used tap water and overwatered, and the marijuana wilted and died.

“It was a disaster,” he recalled. Jones organized the class and an online “THC University” for home growers, but his own thumb isn’t green. Jones said he’ll be buying his marijuana from professional growers.

The course showed would-be grower Cael Nodd, a 34-year-old stagehand in Denver, that marijuana gardening can be an intimidating prospect.

“It seems like there’s going to be a sizable investment,” he said. “I want something that really tastes good. Doesn’t seem like it will be that easy.”