It’s not easy being a house plant. Too often, it’s expected to have the endurance skills of a French Foreign legionnaire along with a supernatural ability to tolerate extreme swings of temperature, famine, drought and flooding. Even – admittedly, the very worst case scenario – occasional cigarette butts, hot drinks, and copious quantities of alcohol (some horribly hungover, force-fed examples of the latter can be seen in a few busy Dublin city pubs).

Just ask Sam Smyth, owner of Urban Plant Life on Dublin's Cork Street, a long-established business that supplies thousands of indoor plants to several hundred Dublin offices and premises including Leinster House, as well as to advertising, television and film productions such as Ardmore Studios' Penny Dreadful.

Christmas, he, says, is the time of highest casualties.

“Let’s just say that office parties aren’t always kind to them. After that, many premises are locked and shuttered up for the holidays, with heating off or down to a minimum, so that the plants must endure no light, no water and low temperatures for a week or more.”

And yet, when chosen with care and treated with just a little TLC, these plants have the ability to transform our homes and offices in a world where many people now spend 90 per cent of their time indoors.

Ever heard, for example, of the phrase 'personal breathing zone'? It's something akin to your personal body space, an area of roughly 6-8 cubic feet surrounding any individual. Place the right house plants within or close to that zone and, studies by Nasa show, they make us healthier by growing fresh air, adding humidity, and filtering toxic gases, volatile chemicals, and other pollutants from the atmosphere – all important considerations in modern, often hermetically-sealed buildings.

Health aside, house plants make us happier by greening and personalising our homes and work places, something that Sam Smyth can also vouch for.

“During the economic crash, some employers cut back on office plants as a way of reducing overheads. What struck us when it came to removing the plants from those offices was how sad many of the employees were to see them going.”

Very possibly those same employers grew to regret their decision. Research shows that indoor plants, used in the right combination and in sufficient numbers, can also reduce a building’s energy requirements by as much as 15 per cent while improving human productivity by up to 20 per cent.

So back to that thorny question of how to keep them alive. Start by following the age-old adage of ‘the right plant for the right place’. Most indoor plants are natives of tropical/ subtropical climes and do best in a steady temperature of 18-24 degrees, although many will tolerate lower. So avoid placing them right next to windows, doors, radiators or heating vents where temperatures fluctuate wildly.

Light requirements also vary according to the particular species. Few (cacti and succulents are the exceptions) like constant direct sunlight. Similarly, almost none will thrive in full shade (exceptions include the vine-like elephant-ear philodendron (P domesticum) and the red-emerald philodendron (P erubescens). Instead, the majority do best in semi-sun/ semi-shade, and when given adequate amounts of water and regular misting.

To gauge if a plant has been sufficiently watered, lift the pot. It should be heavy but not dripping. Avoid overwatering by using containers with drainage holes, and by allowing the compost to partially dry out between watering to the point where it’s barely moist to the touch. As a rule, house plants require more water and regular liquid feeding during spring/summer.

Wiping the leaves with a damp cloth also helps keep plants healthy and happy by keeping the microscopic pores on the surface of the leaves clear. This also reduces the likelihood of pests such as mealy bug and scale insects.

If plants do get infested by these pests, avoid toxic chemical insecticides, and instead treat with a homemade spray using a drop of washing-up liquid, a teaspoon of vegetable oil and four fluid ounces of warm water mixed together. If that doesn’t work, then spot-treat using a cotton bud dipped in surgical spirit.

As someone who’s tried many different kinds over the years, Smyth singles out the handsome upright Kentia palm (Howea forsteriana) as one of his go-to indoor plants.

"It's very tough and will tolerate quite an amount of neglect as well as extremes of temperature as long as you keep it out of direct sunlight and away from radiators." Another is the dragon tree (Dracaena marginata), a native of Madagascar. "A toughie, and a really good air-cleaner that will tolerate semi-shade and dry air."

Where light levels are good, he recommends the weeping fig (Ficus benjamina). “Great for removing air-borne pollutants, its only downside is that it hates being moved and will drop its leaves until it adjusts to its new surroundings.”

Other reliables include the peace lily (Spathiphyllum), also excellent at removing air pollutants, and the spiny snake plant, Sansevieria trifasciata, commonly known as mother-in-law's tongue, a good choice for the bedroom because of its ability to convert carbon dioxide into oxygen during the night. Like all spiny plants, avoid the latter in households with young children.

Specimens of these as well as countless other unusual and exotic indoor plants and a mind-boggling array of pots and containers fill Urban Plant Life’s centuries-old stone buildings and greenhouses on Cork Street, along with a new outdoor plants sales area. For anyone considering cleaning/ greening up their personal breathing zone, I’d highly recommend a visit.

This week in the garden:

Order seed of tomatoes. For inspiration, check out Dublin gardener and 'tomatophile' Nicky Kyle's blog at nickykylegardening.com.

Amongst her favourites are the cherry tomato 'Maskotka' (available from Thompson & Morgan) and 'John 'Baer' (available from seedsofdistinction.com). The latter she sows under heat from late January for an early crop.

Among my own current favourites is the meaty beefsteak 'Paul Robeson'– which are available from seedaholic.com and recommended to me by another well-known tomatophile, Jean Perry of Glebe Gardens – and 'Chocolate Stripe' (brownenvelopeseeds.com).

If you have the low-growing, pretty flowering plant known as Mexican Fleabane or Erigeron karvinskianus in your garden (and given its propensity to seed itself around the place with generous abundance, there's a good chance that you do), then start cutting back the faded start flowering stems to ground level over the next few weeks to encourage the development of bushy, free-flowering plants.