School officials said no way, despite support from dad, a regular weed user and chief executive of a dating app and social network for fellow enthusiasts.
"They didn't want to touch it. They weren't ready to touch it," said Mitchem, who is divorced and shares custody of his kids, ages 11, 9 and 7.
That was early 2013. Now, pot is everywhere in the state, along with three others and the District of Columbia that pushed beyond sanctioned medicinal use to legal consumption just because.
Mitchem, 44, has been speaking openly to his kids about cannabis since he first entered the industry a couple of years ago. He co-founded the app High There! in addition to running it.
So how has legal weed changed the parenting pot conversation for him and others raising kids while working in the fast-growing business segment?
"My kids know everything," he said. "My 11-year-old son is the playground educator. They know probably more about cannabis than most grown-ups who are not in the space. We talk about the facts. We talk about the science."
Mitchem doesn't fire up around his kids, but he has partaken of small amounts in edibles "when we're all hanging out together, watching a movie or something like that."
He added: "They're very aware of the cannabis brownies that are in the refrigerator that they're not allowed to touch."
It's also not OK for them to try pot in any other form. Not only is it illegal since they're under 21, but it's bad for their developing brains, dad said.
The pot conversation can be trickier for industry folks like him, but he said all parents trying to find their way through the talk amid rapid acceptance of legal marijuana can benefit from some basic research before spouting: "Because it's bad, Johnny."
Has Mitchem's work and pot use changed the way he is perceived among other parents?
"As a cannabis business person I've been all over the news, so the parents of my kids' friends know me," he said. "Some kids' parents won't let their kids hang out at my house. They don't say why. Other parents are fascinated by it."
Cassandra Farrington, 43, is co-founder and chief executive of Marijuana Business Daily, a Denver-based industry publishing and conference planning company. She's also a Girl Scout troop leader and mom to a 10-year-old girl and 8-year-old boy.
Farrington and her husband do not use cannabis, but she acknowledged her timeline for talking to her kids about it was likely accelerated by her work. In Colorado, where pot shops are plentiful, not having the pot conversation isn't an option.
"It comes up on the evening news. You drive down the street and you're passing a dispensary and there's a funny smell," she said.
Farrington's company held its first national cannabis conference in Denver soon after the state constitution was amended in 2012 to allow for adult recreational consumption. It was a high-profile affair.
"That's when I basically got 'outed' within my local social community. Some parents in my Girl Scout troop were like, 'Wait a minute, I know her,' and that sort of thing," she said. "Now it's absolutely fine."
In addition to Colorado and the District of Columbia, Washington state, Oregon and Alaska have legalized marijuana for recreational use. A number of states have also decriminalized the possession of small amounts of pot and passed medical marijuana laws.
Brittany Driver, 30, owns a cannabis public relations agency in Denver, writes frequently about the industry and is co-chairman of a chapter of Women Grow, which supports women in the business. She is a user of medical marijuana to stimulate her appetite, and she has a 3-year-old son.
"Even with legal marijuana, there was still a lot of trepidation," she said. "Is a neighbour going to report me because they see I have a child? But over the past year, things in Colorado have calmed down quite a bit as far as that goes. Outside of Colorado, there are still big problems going on with parents and just being able to use it as medicine and have a child."
Bruce Barcott, 49, is a pot user for both medical and recreational purposes. He lives outside Seattle and consumes about once a month, but never around his kids, a 13-year-old son and a 16-year-old daughter. He's also the author of a new book on the future of legal marijuana in America, "Weed the People."
"I had real qualms as a parent writing this book," he said. "I mean, here I am writing a book about pot and I've got two young teenagers in my house."
His pot conversation has been a running dialogue, he said.
"We would stop and start in little snippets, maybe on the drive to school or over dinner. My daughter, especially, thought it was hilarious that her father was writing a book about pot. It's an interesting opener," Barcott said. "I wanted to really talk with them about marijuana in a way that came from a place of honesty and factual data and truth and not have to resort to some sort of scare tactic to keep them off pot."
Pretending, in a legal or illegal state, that teens aren't going to encounter marijuana is not realistic, Barcott said.
"I told my daughter, 'Look, it's hard enough to maintain a good GPA as it is. Imagine trying to do that when you're drunk three nights a week or if you're using pot,'" he said.
Barcott remembers the time he brought home a small cannabis plant to photograph and study for his book. It did not go unnoticed by his kids.
"They were, like, 'Is that a pot plant?' We had a great conversation," he said. "We said, 'Look, this is a marijuana plant. It's been demonized for 75 years. This is where marijuana comes from. It's just a plant, so look at it, smell it, touch it, feel it. Check it out, then it goes down the disposal in five minutes.'"Suggest a correction