Once you’ve exhausted the jokes about green thumbs, red eyes, and the hilarity of growing weed instead of blooms, the questions remain about how to go about growing your own marijuana, if you want to.

Amendment 64 allows home cultivation of marijuana, up to six plants per adult. (Denver’s rules allow a household of two or more adults to cultivate a total of a dozen cannabis plants.) That’s going to appeal to those partakers who are old enough to be leery about openly buying a substance that still remains, on the federal level, strictly illegal.

And it’s going to appeal to many who live in a Colorado town or county that doesn’t allow retail stores — and there are quite a few of those, especially on the Eastern Plains. Even within the county of Denver, the retail marijuana scene is a confusing patchwork: Legal in Glendale, but not in Englewood; legal in Denver but not yet in Edgewater.

Even in jurisdictions that don’t allow retail marijuana shops, it’s legal to grow your own on your own property, within the specifications of Amendment 64.

But for home growers, there’s been the problem of where to acquire seeds or cuttings. Unless they received it as a gift, they couldn’t obtain cannabis plant material without risking a step on the wrong side of the law. That changes on Jan. 1 when retail marijuana shops will open and can legally sell plants and seed.

Still, it’s not like home growers can call a Colorado State University extension agent for growing advice; those experts are prohibited from answering any questions related to marijuana. Even though Amendment 64 specifically allows advice on growing marijuana, greenhouse and nursery staff often shy away from the subject.

“It’s crazy,” said Sharon Harris, executive director of the Colorado Nursery and Greenhouse Association.

“We started getting those calls when the bill first passed for medical marijuana, and our attorney advised us not to talk about it. It’s legal in Colorado, but still a federal offense. We’re waiting to see how the legal retail sales work out, but our position will not change until the U.S. attorney general says, ‘OK, here’s the deal.’ It’s quite a quagmire.”

So don’t expect help from the usual horticultural resources. Instead, look at hydroponic indoor gardening retail outlets, and start-ups like Cannabis University, which offers a $250 one-day class in possessing and growing marijuana.

Be advised: Under the law, growing your own marijuana requires keeping your plants in an “enclosed, locked space” that is not open or public. That’s pretty broadly-written, but a safe interpretation would mean a basement room or closet that can be locked.

No more than three of your plants can be in the flowering stage at one time. And it remains illegal to sell marijuana you grow.

To answer basic questions for novice pot-growers (potters?), we interviewed George Archambault, owner of MileHydro, Ben Holmes of Centennial Seeds, and Michelle LaMay of Cannabis University.

Q: What will I need to start growing weed?

Holmes: The basics are one container per plant; potting soil; fertilizer; a good-quality grow light; and seeds.

Archambault: Ideally, you’ll have a controlled environment, with fresh air coming in through a ventilation system and exhaust air going out the opposite end of the room, because plants don’t do well in stagnant air. If you use a controlled environment like a tent or cabinet, you’ll want a thermostat to make sure the room stays at the same temperature instead of getting too hot.

LaMay: A grow light with a vegging bulb and flowering bulb, a controlled environment, like a room or a tent; nutrient supplements; an outside air source; a carbon filter; a thermometer; an oscillating fan to move the air about; a can fan to pull air out through the carbon filter; timers; a PH tester for the water; a five-gallon water container; pots; growing medium; tarps for the floor, even with a grow tent; and only highest-quality extension cords, if you must use extension cords at all.

Q: So what’ll that cost?

Holmes: For a very basic set-up, around $500. Figure $20 for the containers, $40 or so for the soil, another $40 for the fertilizer and nutrients, $300 for a decent grow light, another $100 for a vegging bulb and a flowering bulb. Figure on spending $5 to $10 per seed, but prices vary widely. Some seeds cost $1,000 apiece.

Archambault: Five hundred is cutting a lot of corners. I’d say more like $1,000.

Q: Does it make more sense to try to grow hydroponically?

Archambault: I don’t advise new growers to start right in with hydroponics. That means spending at least $1,000 on equipment, and that’s a lot for a beginner. And you’re out all that money if you’re not successful.

Q: How much space would a $500 dirt set-up require?

Holmes: That’d be for a 4-by-4-foot area, so you’ll need only one grow light, plus one grow light with a white-blue vegging light bulb and an orange-red flowering light bulb.

Q: What’s a “vegging light bulb”?

Holmes: In indoor gardens, you mimic the spring and summer growing period with a light that’s on the white/blue spectrum. In the vegging state, you’re encouraging the plant to produce leaves, with a goal of growing the plant to half the size you want it to be when you harvest it. The rule of thumb is giving the plant 18 hours of light in the vegging [short for vegetative growth] stage. So if you want a 3-foot-tall plant at the harvest stage, you want to veg it until the plant is a foot and a half tall.

Q: Then what?

Holmes: When it reaches half the size you want it to be, then you have to trick it into flowering by making the plant think it’s fall. The flower is what people want from a marijuana plant, because you harvest the flower buds. So then you switch to the orange-red light bulb. That makes the plant think it’s fall, and it will induce flowering. During the flowering stage, you’ll want to give it 12 hours of light on, and rest it in the dark for 12 hours.

Q: That sounds like a ton of work. Is it easier to start with cuttings?

LaMay: Cuttings are easily accessible from friends or the medical marijuana dispensary or, soon, the retail store. They are about $10 each. They must be quarantined and doused aggressively with organic neem oil over 20 days.

Archambault: Start from seeds. I’ve never met anyone who bought a clone from a dispensary that wasn’t infested with spider mites or powdery mildew. It’s an indoor growing issue. The worst thing you can do is buy a plant that has a lot of insects.

Holmes: No! Start with seeds. We urge people not to buy cuttings, and my dispensary clients will hate me for saying that, but the worst thing you can do is buy their cuttings because they’re infested.

Q: Where can I buy seeds?

Archambault: After Jan.1, 2014, you can buy cannabis seeds in Colorado without a medical marijuana card. Seeds, and cuttings, will be sold at state-licensed marijuana retail stores. But remember, you can’t tell whether a seed is male or female. You have to wait until it germinates. It takes about a month to see the telltale signs of the first budding flowers. The males only grow leaves.

Q: Why does it matter whether the seed is male or female?

Holmes: Only the female seeds produce flowers, which is the crop you want. Some companies sell what they call “feminized seeds” that have a higher probability of being female. But regularly-bred seeds is what we recommend.

Q: Is growing marijuana comparable to starting tomatoes or other garden plants?

Holmes: Yes, it’s like growing a tomato. Marijuana is a plant that’s very sensitive to over-feeding. You need to lime the soil, because they don’t like acid soil. And I just use Miracle-Gro. I use that on everything. If you ate my tomatoes or zucchini, or smoked my weed, you’d come back for more. You don’t need to buy a lot of supplements and amendments and products. You need a bucket of dirt and a well-thought-out fertilizer plan, not 20 different fertilizers and nutrients. The best thing is to keep it simple.

Q: I have relatives who live in states that haven’t legalized marijuana. Will they be able to tell I’m growing it?

Archambault: Well, the plants are still going to release that telltale aroma. Hydroponic stores sell odor mitigation systems. Carbon filters are the most effective. If your grow system is in a basement room that nobody uses, maybe they won’t notice.

Q: What about pets?

Holmes: Cats will be kind of curious. Pets are disease-carriers, and your pet could infect your plants. Make your grow room off-limits to your pets.

Claire Martin: 303-954-1477, cmartin@denverpost.com or twitter.com/byclairemartin