PLANTS ADD MUCH to a Harvard student's room: companionship, love and sheer sensuality. And sometimes you can wrap them up in a joint and smoke them.

Tom Greenthumb, Johnny Appleseed and Mel Brooks (not their real names) are part of a select Harvard circle: students who grow their own marijuana. Hidden inside their closets (their real closets), the plants offer them a relaxing, educational hobby and a good high.

Tom began growing his pot at home last July, moving the plants into his Cambridge room in September. He harvested his first crop during the winter, smoked it and is currently growing his second batch.

And he's planning ahead. "When I'm older, I don't want to have to still be buying pot from the criminal element," Tom says. "If I start growing now, I can learn to be self-sufficient."

In addition, Tom says homegrown pot is fresher than commercial pot. "In homegrown, less of the THC has converted to CBNs," he says. THC, or tetrahydrocannabinol, is what creates the mild psychedelic effect of marijuana. CBNs, or cannabidiolic acids, produce effects such as drowsiness and red eyes.

Though not a botanist by trade, Tom has learned much about dealing with flora (Part of this education has been supplied by Harvard, which boasts several books on marijuana-growing in its libraries). Tom's remaining 15 plants--he originally began with 50--were raised from four different types of seeds that he took from pot he bought: two types of sativa, one indica from West Virginia and one hybrid of the two.

"Indica has large buds at the top of the plant and has a higher potency per weight," Tom reveals. "Sativa has skinnier buds that are all over the plant and give a cleaner high."

Both Tom and Johnny say their pot would go for about $400 an ounce once it is harvested; Johnny estimates he will probably end up with an ounce or two, and Tom says he will have a little less than an ounce. However, both of them stressed that they have no interest in selling the fruits of their labor. "I'm going to smoke it myself," Johnny says.

ALL THREE GARDENERS use similar setups and processes in their closets. When the plants are small, they bombard them with fluorescent lights 24 hours a day; then they switch the lights to a 12-hour cycle and the plants begin to bud. "You fool them into thinking it's winter," says Johnny.

In addition, Tom bends his plants over so they grow horizontally. "It increases the yield by increasing the surface area at the top portion of the plant," Tom says.

Once they begin to bud, the gardeners remove the male plants, which are taller and distinct from females. "You don't want the male plants to pollinate the females, because then you will have seeds," Tom says. Sensemilla ("kind bud"), which is pot without seeds, is considered higher quality.

However, Johnny manually fertilized some of his females, a statement which would be disturbing in a different context. "If you just harvest females, you have no seeds for later," he says. Using his finger, he took pollen from the males and put it on some of the females so he'll be able to spawn another crop from the current one.

MEL has taken a different route to his pot-growing. That is, he hasn't been successful. Inspired by the success of Tom and Johnny and a recent cover story in the New York Times Magazine about the technology of growing marijuana, Mel started his first crop in February. The plants wilted and died one by one. "I think I overwatered them," Mel says. Nevertheless, he smoked their remains.

For his current crop, Mel has rearranged the lights and tried different containers. He began with 18 plants and is now down to one. Well, actually two. "There's another weird plant that's growing in there that isn't pot," Mel says. Compared to the forest in Johnny's closet, Mel's closet looks like it has been clearcut. Next to one sickly plant is a pencil, stuck in the soil "to support the plant so it won't tip over."

While Tom named some of his plants after Twin Peaks characters (Catherine, Laura Palmer, Audrey) and Johnny often plays music to his "little ones," Mel decided that he didn't want to become too attached to his plants. "It's like in the olden days, when parents wouldn't name their kids until they were three or four years old because of the high death rate," he says.

Mel was successful in polluting his room, though. "I used organic fertilizer," he says. His roommate puts it bluntly: "He made my room smell like shit," says Nigel Tufnel (not his real alias).

Not so for Tom and Johnny. They have no qualms about inorganic chemicals; they both use MiracleGro. Johnny's room has a pleasant pot aroma, but he says the smell doesn't give him away. "I don't think there's too many people who know what growing marijuana smells like."

Yet Johnny says he has had nightmares about getting busted. "One time maintenance came in to fix something and the pot lights were on, but my roommate was here and moved everything out of the way," he says.

Nigel also worries about Mel's plant(s). "It makes me nervous whenever some random person sticks his head in our room."

Note: Since this article was written, Mel's last plant has passed away. There will be a service in Memorial Church on Sunday.