Keeping a gifted orchid alive, and getting it to flower again

What you have actually been given

The orchid most people receive as a gift is a moth orchid, Phalaenopsis, and almost everything that goes wrong with one comes from treating it like an ordinary houseplant. In the wild it grows on trees rather than in soil. It clings to the bark of branches in warm, humid forest, its thick roots wrapped round the wood and hanging in the air, catching rain as it runs past and drying off again within hours.

That habit explains the pot it arrives in. The chunky bark, the clear plastic container and the roots that climb out over the rim are not signs of neglect. They are the grower giving the plant something close to a branch: a loose, airy footing that holds a little moisture and lets the rest drain straight through. Keep that picture in mind and most of the care follows from it.

Let the roots tell you when to water

Orchid roots are covered in a spongy, papery layer called velamen, which soaks up water in seconds. It also changes colour as it does so, which makes it the most reliable watering gauge you will ever own. Dry roots look silvery or pale grey-green. Freshly watered roots turn a clear, bright green. Look through the side of the pot: when most of the roots have gone silvery and the bark feels dry an inch down, it is time.

That is why there is no honest answer to how often. A plant on a warm windowsill in summer may want water every few days; the same plant in a cool room in winter may go a fortnight or more. A fixed schedule waters a plant whether it needs it or not, and overwatering kills far more orchids than thirst does, because roots that sit wet run out of air and rot.

The method matters as much as the timing.

• Take the plant to the sink in its clear inner pot and run tepid water through the bark for a minute or so, or stand the pot in a bowl of water for ten minutes so the bark can soak.
• Let it drain completely before it goes back into its decorative pot. Tip out any water that collects in the bottom later; a pot left standing in water is the commonest way to rot the roots.
• Water in the morning and keep water out of the crown, the cup where the leaves meet, since water left sitting there overnight can rot the plant from the centre.
• Use rainwater, or tap water that has stood until it reaches room temperature, rather than water straight from a cold tap.

Bright light, but not direct sun

Under the forest canopy a moth orchid lives in dappled shade, and indoors it wants the same: plenty of light, but little direct sun. A bright east-facing window is ideal, and a west- or south-facing one works with a sheer curtain between the plant and the glass. Midday sun through a closed window can scorch a leaf in an afternoon, leaving a pale patch that turns brown and never recovers.

The leaves report on the light. A healthy plant has firm, mid-green leaves. Very dark green, floppy leaves usually mean too little light, and a plant in that state will live but rarely flower. A yellowish cast, or a reddish tinge along the edges, means too much. In winter, move it away from cold glass at night and away from radiators, which dry the air and the roots together.

Why the buds fall before they open

The most disheartening thing an orchid does is drop its buds in the first week, before they have opened. It is almost always a reaction to change rather than a sign the plant is dying. A moth orchid that has spent its life in a steady glasshouse, then a delivery van, then a warm living room has had a great deal to cope with, and closed buds are the first thing it sacrifices.

Draughts, a sudden drop in temperature, a spell beside a heater and a pot allowed to dry out completely will all do it. So will ethylene, the ripening gas given off by fruit, which is one good reason an orchid should not share a table with the fruit bowl. Find the plant a spot that suits it and then leave it there. Open flowers are far tougher than buds, and on a settled plant they can last for many weeks.

After the last flower falls

When the final flower drops, the plant is not finished. It is resting, and what you do with the bare flower spike decides how soon you see flowers again.

• If the spike has turned brown or yellow and dried out, cut it off close to the base. It will not flower again.
• If the spike is still green, you can cut it back to just above a node, one of the small ridged bumps along the stem, below where the lowest flower was. A side shoot will often grow from that node and flower within a few months.
• Alternatively, remove the green spike at the base. The plant then puts its energy into new leaves and roots, and tends to produce a stronger spike later.
• Leave the leaves and aerial roots alone. A root growing out over the rim is not a fault to be trimmed; it is the plant doing what it would do on a tree.

Getting it to flower again

A moth orchid usually reflowers once it has grown at least one new leaf since it last bloomed, and the trigger it most often needs is a cooler spell. Guidance from the Royal Horticultural Society and the American Orchid Society points to the same signal: a few weeks in which the nights are noticeably cooler than the days. In many homes that happens without any help in autumn, which is why so many gifted orchids surprise their owners by flowering again the following winter. A plant kept at one steady warm temperature all year often simply goes on growing leaves.

While it is growing, feed it lightly with a fertiliser made for orchids, at the strength the label gives or weaker, rather than a general houseplant feed at full strength, because orchid roots are easily scorched by strong feed. Every year or two, once the bark has begun to break down and hold water like compost, repot it after flowering into fresh orchid bark, in a pot only just big enough for the roots. Ordinary potting compost stays wet and suffocates them.

Signs worth acting on

Most orchid problems start at the roots, so when something looks wrong above the pot, slide the plant out and look below it.

• Brown, mushy or hollow roots mean rot from too much water. Cut them away with clean scissors, repot into fresh bark and water less often.
• Wrinkled, leathery leaves can mean either thirst or rot. Firm, silvery roots point to thirst; soft brown ones point to rot, because a plant with no working roots cannot drink however wet it is.
• Sticky patches or tufts of white fluff where the leaves meet the stem are usually mealybug. Wipe them off with a cotton bud dipped in soapy water and check again every few days.
• One lower leaf turning yellow now and then is normal ageing. Several at once is not, and usually points back to light or water.