Some of the most fashionable retro species include cheese plants and dragon plants, while urban dwellers opt for peace lilies because they purify the air.
Among the top sellers are alocasia – varieties of which are commonly known as elephant ear – with sales up tenfold. Species include Alocasia zebrina, which has eye-catching yellow and black zebra markings on its stems.
Around 1,300 prayer plants have been sold this year, while sales of ferns have doubled.
More than three-quarters of those aged 16 to 34 have a houseplant, a recent Ipsos Mori survey said.
Experts say the renting generation can not afford gardens or do not want to invest in beds only to move on. Some owners said they enjoy looking after the plants and watching them grow, and others believe they help their mental health and wellbeing.
Teenagers at Wisley, the UK's second most-visited garden centre, tend to opt for cacti, small succulents and carnivorous plants such as Venus flytraps.
Those aged 20 to 35 are more likely to buy pots with large foliage such as cheese plants and snake plants.
The older generation favours African violets, begonias and other flowering varieties.
Duncan McLean, senior plant buyer at Wisley, said: 'The market's been increasing year-on-year. The health and wellbeing element is the number one reason people buy houseplants.
'It is also as millennials and the Instagram generation like to improve their surroundings and the place that they live in.
'There's also a bit of a retro thing and plants which improve the environment and purify air are selling well too.
'But the plants aren't cheap. It's not unusual for someone to spend more than £50 on a single plant.'
Damian Powell, head of retail, said: 'We have really focused on getting our houseplant and pot offer right, trying to link more with trends and attracting a younger shopper to come to us.'
Sales of spring bulbs at Wisley are up by a third and seeds by a half, while sales of indoor flower pots have nearly tripled.
Online outlets such as Patch are also benefiting from the trend – selling plants with names such as Robin the Rubber Plant – while Ikea said its houseplant sales are up two-thirds on a year ago.
