Orchid Care: Light, Water, and Humidity Basics

A moth orchid on a British windowsill is quietly doing something remarkable. It is surviving in a home that is drier, darker and more centrally heated than the humid forest canopy it evolved in, and it is still producing flowers. Get three things roughly right — light, water and humidity — and your orchid will carry on for years rather than sulking politely in a corner.

Light: Bright, Indirect and Short of Blazing

Almost every orchid sold in the UK is a moth orchid, a Phalaenopsis, and they want the light of a bright room without direct summer sun. An east-facing windowsill is close to perfect: gentle morning sun, then soft light for the rest of the day. A south or west window will work if you hang a sheer curtain between March and September, or stand the plant a metre or two back from the glass. A north-facing window usually keeps the plant alive but rarely persuades it to flower.

Learn to read the leaves. A healthy leaf is mid-green and firm, with a slight sheen.

• Too much light: yellow-green leaves, a bleached papery patch in the middle of a leaf, or crisp brown edges at midday.
• Too little light: dark, glossy green leaves that feel limp and floppy, and no new flower spike for a year or more.
• Just right: steady growth, a new leaf every few months, and roots that stay plump.

Give the pot a quarter turn each week so the plant grows evenly. Flower spikes naturally lean towards the light, and a plant that is never turned will end up lopsided.

Watering: A Proper Soak, Then a Proper Drain

More orchids are lost to kindness than to neglect. In the wild, roots are exposed to air and dry out between rain showers; in a pot, they sit in whatever moisture the bark holds. Water when the roots turn silvery-grey — usually every seven to ten days in spring and summer, and every ten to fourteen days in winter. Lift the pot: a light pot means dry bark.

• Use tepid rainwater or filtered water where you can. Hard tap water leaves a white crust on bark and roots over time.
• Take the inner pot to the sink and run water through the bark for about fifteen seconds, or stand it in a bowl of water for ten minutes.
• Let it drain completely before returning it to the decorative outer pot. Never leave a puddle sitting around the base.
• Water in the morning, and keep water out of the crown and the leaf joints, where rot begins.

If in doubt, wait a day. An orchid that is slightly dry will recover; one with soggy roots usually will not.

Humidity: Beating the Central Heating

Moth orchids are happiest at roughly 50 to 70 per cent humidity. A heated British living room in January often sits at 30 to 40 per cent, which is why leaves wrinkle and buds drop. You do not need a greenhouse — you need to raise the air around the plant a little.

• Stand the pot on a tray of pebbles with water kept below the pebble line, so roots never sit in it.
• Group orchids together with other leafy houseplants; they humidify one another.
• Mist the leaves with tepid water in the morning, never in the evening, so moisture dries before night.
• Keep plants away from radiators, and out of cold draughts from doors and letterboxes.

Bathrooms and kitchens with decent light are often the most orchid-friendly rooms in the house, simply because everyday steam does the work for you.

The Roots Report the Truth

Healthy roots are plump and silvery-green when dry, turning a soft olive green after watering. Brown, mushy or hollow roots mean too much water; papery, shrivelled roots mean too little. Trim dead roots with clean scissors and repot into fresh bark.

Bark compost breaks down after eighteen months to two years and then holds water like a sponge, which is the usual cause of a sudden collapse in an otherwise well-kept plant. Repot in spring, into fresh orchid bark and a pot only slightly larger than the old one. Orchids like to be snug; too much compost around the roots stays wet for too long.

Seasonal Adjustments Through the Year

Orchids respond to small shifts in temperature and day length, and adjusting your routine to the calendar pays off.

• Spring and summer: water more freely, shade from midday sun, and feed weakly every second or third watering.
• Autumn: a two to three week spell with night temperatures around 15°C and days near 20 to 22°C is the classic trigger for a new flower spike.
• Winter: ease back on watering, move plants off cold windowsills at night, and keep them away from radiators. Daytime temperatures of 18 to 24°C with slightly cooler nights suit them well.

Cut a spent flower spike back to just above the second node if the plant is strong, or to the base if it looks tired, and let it rest. With the right light, careful watering and a little extra humidity, most orchids will reward you with flowers once or twice a year for a decade or more.