The team behind the local obsession, Canberra's hipster florists Moxom and Whitney, said they were amazed by the continued popularity of their weekly courses, which often booked out within minutes and had a waiting list stretching for months.

Having started the evening classes in February this year, while also providing an increasing number of professionally designed terrariums for sale, one half of the botanical duo Lou Moxom said there were now thousands of terrariums decorating Canberra homes.

"It's like we have infiltrated the city!"

The trade in store-made mini-gardens was also booming to the point where it was close to rivalling flower sales.

Part of the appeal of the terrariums was the addition of miniature people and animals, which turned a few tiny plants into a virtual and inhabited mini-forest under glass.

The first Moxom and Whitney terrarium was created by Belinda Whitney in 2012 after the pair spotted one in a tiny pop-up store in Melbourne when they went on an ideas-gathering trip prior to setting up their first store on Lonsdale Street, Braddon.

"Whits was like, I can make that, and sure enough, she made one when she got home. It is still alive and living in her ensuite, and it is so lush and overgrown you can't even see the people in it."

There were some basic rules on maintaining a happy and healthy terrarium which the pair imparted on every course.

"Mainly, we find people over-love and over-water them. They kill them with kindness … Our philosophy is to treat them mean to keep them keen."

Ms Moxom put the class popularity down to a chance to do something a bit different, to get creative and dirty, and to take home a living garden.

The fact that classes included gourmet cheese and sandwich platters and a glass or two of bubbles was also a drawcard to birthday parties, hen's nights and a girl's night out.

Of the hundreds of terrarium school graduates this year, less than half a dozen are men.

"But when the blokes do come, they have an awesome time," said Ms Moxom.

Classes have catered for all ages between 8 and 86.

Unlike the 1970s terrarium craze, Ms Moxom said she did not see the terrarium going the same way as platforms, ponchos and tie-dye.

"We are in an era of renewing, reusing and upcycling, and now we are more inclined to hold onto our possessions. I don't see terrariums as a passing trend at all."

Not everything is coming up mossy in the terrarium classes, however, with Ms Moxom alluding to a darker side of fern and figurine placement.

Apparently the competition to grab the cutest human characters led to some rather unsavoury tactics from competitive clientele.

"Yeah, we had a few fights over the people, it got a bit tense, so now we just do animals."