- Family: orchids (Orchidaceae)
- Botanical names include Phalaenopsis, Dendrobium, Oncidium, Zygopetalum
- Type: Epiphytes, mainly
- Location: House or glasshouse for most
- Aspect: Bright, indirect light or some shade
- Moisture level: High
- Room temperature: Varies according to species
- Hardiness: H1B to H1C for houseplants
- Difficulty: Average to challenging
Bewitching and graceful, orchids easily outdo most other flowering houseplants in looks and longevity. The exotic flowers last for weeks, sometimes months, and resemble the far-away jungle that they hail from, injecting the home with strange beauty and tropical colours. They have a deserved reputation for being tricky, but there are some that can be grown successfully as houseplants in the right conditions, and – once you know how – orchid cultivation can become addictive.
There are a mind-boggling 28,000 species of orchid, within 707 genera. Because orchids are found all over the globe (apart from Antarctica), it is assumed that they existed 100 million years ago before the continents broke away from the Pangaea land mass. Their ancient past is perhaps one reason people become obsessed with them: during the orchid mania of the 19th century, plants sold for eye-watering amounts of money and, still, today, continue to fetch great sums, often on the illegal market.
In the west, the flower has a rather sordid image: not just because it is a symbol of malefic magic and sex, but because a lot of people have died or courted danger whilst collecting it. For example, in 2000, plant hunter Tom Hart Dyke was held hostage for nine months in the Darién Gap jungle of Panama and Columbia after entering it to find orchids. However, in other parts of the world, the orchid holds no sinister connotations: in China, for instance, where orchids have been cultivated for longer than anywhere else, they are symbols of virtue and associated with Taoism.
Orchids vary hugely in size: from a couple of millimetres to many metres. Vanilla planifolia, which produces vanilla pods, can grow into a 30-metre vine in its native Mexico; while the tiniest species require a microscope to be seen properly. Some orchids hail from temperate climes and can therefore be grown outside in Britain; over 50 species are native to the UK, including the common spotted orchid (Dactylorhiza fuchsii), which blooms en masse on chalk downland in summer. However, most orchids come from the tropics, where their bold colours blaze as bright as parrot wings amid lush jungle greenery; some bloom high up in the sun-drenched tree canopy; others are found on the moist, shady forest floor. As houseplants, these conditions must be recreated as much as possible. Radiators are like kryptonite to orchids, regular repotting is required, and they turn their noses up at tap water. But they are worth all the fuss, being so very weird and so very wonderful, and far more exciting than a vase of flowers.
Which orchids to grow
For an easy life, opt for the moth orchid, Phalaenopsis, which copes far better in a British house than any other genus. Other options include Dendrobium, Zygopetalum, Oncidium, and the Cambria group, all of which can be grown as houseplants in the right conditions. They make a refreshing change from ubiquitous Phalaenopsis, although, in its defence, the moth orchid is always elegant, and a generous display of white Phalaenopsis is hard to beat.
Where to position orchids
Phalaenopsis - Comprising 78 species, many of which are found in Indonesia and the Philippines, the moth orchid group likes bright (but never direct) light, high humidity, and a temperature of 13 to 27°C. The main flowering period is winter, but the blooms can last for weeks, even months, and the plant can reflower more than once throughout the year.
Dendrobium - The attractive noble orchid (D. nobile) from Nepal and China, which grows on stout cane stems, and the Australian pink rock orchid (D. kingianum), with its pretty lilac-pink sprays, both appreciate high humidity and a bright windowsill and flower better if given a cooler position in winter. D. nobile's temperature range is 13 to 24°C, while D. kingianum grows at 5 to 24°C.
Zygopetalum - From the cool, damp mountains of South America, Z. maculatum produces fabulously exotic purple, green, and burgundy flowers that have a high-pitched hyacinth-like scent and can last for months. In winter, the plants enjoy a bright windowsill, but should be given some shade in summer; sit the pot on a tray of pebbles and water to boost humidity, but don't allow the leaves to remain wet for hours (for example, avoid a damp bathroom). The ideal temperature range is 13 to 24°C.
Oncidium - Encompassing 336 species, the dancing-lady orchids have a variety of needs: some prefer warmth, others cooler conditions. The South American dove orchid, O. ornithorhynchum, which has sherbet-scented purple-pink flowers, enjoys a bright windowsill in winter and light shade in summer, with a temperature range of 13 to 24°C.
Cambria orchids - This group comprises hybrids produced from various genera, including Oncidium. They mostly have showy, colourful flowers and enjoy bright, filtered light at around 13 to 24°C.
How to water orchids
Rainwater at room temperature is one of the secrets of the successful orchid grower, so if you're growing several orchids, it's worth installing a rainwater butt in the garden and then sitting your watering can of rainwater indoors for a few hours until it reaches the right temperature. Water when the compost is only slightly moist, but never leave it until the compost is completely dry. Lifting the pot to see how heavy it is will help to ascertain whether the plant needs a drink.
Watering in the morning is best, especially in hot, sunny weather, when watering may be required weekly. Sit the plant in the sink; pour the rainwater generously into the pot and let it drain away, before sitting the plant back on its tray. Roots growing outside the pot can be misted with a water spritzer until they turn green. If the leaves are dusty, give them a wipe with a damp cloth to boost photosynthesis. When returning your orchid to its windowsill, ensure any developing flower spikes are facing in the same direction they were when you moved the plant!
Most orchids enjoy high humidity, and therefore many suit bathroom or kitchen windowsills, or can be placed on a tray of gravel or pebbles and water.
When to feed orchids
In general, orchids don't like too much food. In the growing season, give them a high-nitrogen feed at a quarter of the strength recommended on the packet, and a high-potash feed at the end of the growing season, also at less than the recommended strength. Alternatively, use specialist orchid fertiliser at the advised strength.
How to get Phalaenopsis to reflower
Once your moth orchid has finished blooming, cut off the spent flower stem 2 to 3 nodes up from the base, in the hope that it will reflower. Repot the plant regularly: at least every two years; ideally, once a year in spring. A clear pot allows you to detect the health of the orchid and its moisture levels, as well as allowing the roots to photosynthesise, but isn't necessary – the size of the pot is more important, with a small container preferable; indeed, the old container may be suitable, if in good condition. Remove any unhealthy or dead leaves and unhealthy or dead roots, and prune healthy, plump roots to around 12 centimetres. Gently get rid of as much of the old compost as you can and replace it with fresh orchid compost or orchid bark; you can also mix in some sphagnum moss, which aids moisture retention.
