Houseplants: how to buy them – and keep them alive

Houseplants aren’t just a way to make your home look better – according to research published this week, some of the most popular pot plants can also have a positive impact on the quality of the air.

Research from the University of Birmingham and the Royal Horticultural Society (RHS) found that in a small, poorly ventilated office measuring about 15 cubic metres, just five small plants reduced levels of the common air pollutant nitrogen dioxide (NO2) by as much as 20%.

The researchers tested low-maintenance, inexpensive houseplants commonly found in UK homes – the peace lily (Spathiphyllum wallisii), corn plant (Dracaena fragrans) and ZZ plant (Zamioculcas zamiifolia) – by putting them into test chambers containing levels of NO2 comparable to those in an office next to a busy road. An hour later, each species of plant had removed about half the NO2 in its chamber.

Exposure to high concentrations of NO2, which gets into the air when fossil fuels are burned, can aggravate respiratory diseases, particularly asthma.

The results are good news for the green fingered, but what if you’re one of those people who struggles to keep anything leafy alive? Investing in plants can seem like a waste of money and time, while watching a living thing slowly die in front of you does not make for a cheerful hobby.

Experts such as Jane Perrone, who presents the houseplant podcast On the Ledge, say it doesn’t have to be this way.

Peace lily plants
Peace lily plants are easy to look after, but will wilt dramatically if they are underwatered. Photograph: Carole Hewer/Alamy

“Those plants are all easy to look after, although the peace lily will wilt dramatically if it doesn’t have enough water,” she says. “I often give the ZZ plant to people who claim they kill plants because it is super tough and adaptable to different conditions, so that’s a good one to choose if you are starting out.”

Perrone says lots of people buy their houseplants from supermarkets or the big box DIY stores, they tend to be cheapest there.

But this is a false economy, she says, because you could end up with a plant that hasn’t been looked after particularly well and wasn’t worth buying. “If a plant has been sitting around for a while, sometimes it could be already stressed and damaged, so when you get it home, it starts to show signs of that stress.”

Instead, if you can, Perrone says it is best to buy from a more specialist grower, such as a houseplant shop or a garden centre, “where there’s actually somebody who’s paid to look after the houseplants while they’re sitting there”.

Online specialist plant shops that provide lots of detailed information about what they’re selling and their living requirements are also worth considering, she says, although “a lot is dependent on the packaging and the courier the website uses”.

When choosing a plant in person, avoid those which have yellow or brown leaves and if you can, take the plant out of its pot and sneak a peek at its roots, the RHS horticulture expert Leigh Hunt says. “What you’re looking for, outside the root ball, is a little trail of little white roots. That would indicate it’s nice and healthy,” he says. “If it’s been overwatered, those roots will be rotten and brown.”

It pays to think about where you are going to put your plant before you buy one, so that you can choose one that is well suited to the environmental conditions of that location.

ZZ plant
A ZZ plant will tolerate almost all lighting conditions except strong direct sunlight. Photograph: Hazrat Bilal/Alamy

Perrone says many people who struggle to keep their plants alive often massively underestimate how much light all plants need: “No plant is going to be happy long term in the darkest corner of the room.”

She recommends either doing your own research online or going to a specialist shop, where staff should be able to help you find something that will suit the conditions of your chosen location. “That’s what you’re paying for, that expertise. The plant may cost you a bit more but hopefully it means you won’t go home with the wrong one,” she says.

When you first take a plant home, bear in mind that even if it is a variety that can thrive in the shade it may struggle at first in a dark spot if it has become accustomed to sunnier conditions. “Don’t think you can bring a plant home, put it on a shelf and not look at it for a month. If you’re new to houseplants, observation is really key,” Perrone says.

Too much watering – or too little – are problems that many houseplant killers have to overcome. “People often ask ‘how many times a week should I water?’” Hunt says. “And it’s really impossible to say because every plant is different, it grows at different rates, in different temperatures, light conditions and seasons … my general advice to people is push your finger into the compost. If that feels moist, or indeed wet, then don’t water it. If it starts to feel slightly dry, then water it well.”

You may need to move your plants around in different seasons or repot them as they grow, so while it’s worth investing in the plant itself, you should avoid spending a fortune on beautiful ceramic pots. “They’re always the wrong size for the next plant you get,” Perrone says. “I buy all my pots in charity shops and repurpose things like salad bowls and casserole dishes.”