Thirty years ago, the idea that an orchid could be anywhere other than in a hot house would have been considered as horticultural heresy.  Now they are sold in supermarkets for the price of a bottle of wine.  Formerly the preserve of specialists with expensive hot houses and specialized composts, advances in tissue culture have made the propagation and care of orchids an inexpensive way of getting exotic blooms into any building.

About orchids

The orchid family is one of the largest plant families, with approximately 28,000 species growing in almost every habitat - including a few wild species in the UK.  To illustrate how big a family of plants that is, more than 10% of flowering plant species are orchids. 

European interest in orchids started in the late 16th Century, when explorers collected plants from their native habitats and brought them back to Europe.  By the late 19th Century, their cultivation had become something of an obsession with wealthy collectors, who paid high prices for new varieties and built special glasshouses to keep them. 

Most of the orchids grown indoors have their natural origins in the tropics and subtropics, where they grow as epiphytes (meaning that they cling onto the trunks and branches of trees) or lithophytes (growing on rocks and cliff faces). 

Many orchid species and hybrids are commercially available, and can be grown as house-plants.  The mystique that used to surround their cultivation has all but disappeared, and expensive hot-houses are no longer required except for the most exotic and rare plants.

orchid display at Chelsea Flower Show

Amongst the most popular indoor species are:

  • Dendrobium, from China, the Himalayas, Southeast Asia and Tropical parts of Australia (the name literally means ‘living on a tree’, which describes its epiphytic habit rather well).
  • Miltonia, a native of Central America named after the Englishman, Lord Fitzwilliam Milton, and which are often known as Pansy Orchids, for the shape of their large flowers.
  • Phalaenopsis, the moth orchids, are found growing wild on the Pacific Islands of Borneo, Java and the Philippines.  The name Phalaenopsis means ‘moth-like’.  They are the easiest orchids of all to keep as houseplants, and we will concentrate on them in this article.

Dendrobium nobile often produces large numbers of highly scented blooms on long canes called pseudobulbs.  Spectacular these may be, but the blooms are very short-lived, and when not in flower, they are not especially attractive to look at.

Phalaenopsis and Miltonia hybrids are similar in many respects.  The flowers, whilst appearing very delicate, are surprisingly long-lasting (due to the scarcity of pollinators in the wild), and the plants are very robust when grown as house-plants.

Phalaenopsis orchids (pronounced fa-leh-NOP-siss) are especially recommended for their visual appeal, and comparative ease of care.  In good conditions, Phalaenopsis will flower for several weeks.  Miltonia, though similar, produces very large flowers that really need some space to display them to their best advantage.

 

How to care for Phalaenopsis orchids

phalaenopsis orchid

Displaying in a decorative pot

Orchids are supplied growing in a special free-draining compost.  They should not be removed from their original pots, which you will notice are made of a clear or translucent plastic.  (You should keep the orchids in their original grow pots: orchids benefit from a little light at the roots, which is why they are sold in such pots.)  Instead, a layer of LECA (light expanded clay aggregate - small pellets of absorbent clay, which you can buy from most garden centres) should be spread in the bottom of the decorative pot, and the orchid pot placed upon it.  

orchid grow pot and LECA granules

Images L - R: Transparent nursery pot, LECA absorbent granules

Alternatively, you can buy special orchid pots, which are often taller than conventional decorative pots.  These are designed so that you can keep a moist layer, or even just water, at the bottom, without the orchid sitting in it.

orchid pots

Images: orchid pots showing supports for the grow pot so that a humid area can be provided underneath

If the decorative pot is large, you may wish to surround the nursery pot with more LECA or even something like glass beads to hold it in place (and let some light in).  Phalaenopsis benefits from a humid environment around the roots, which can be achieved by standing the grow pot on a layer of something like lava rock or LECA in the decorative pot to support the pot, and keep that material moist.

If the decorative pot is large, you may wish to surround the nursery pot with more LECA or even something like glass beads to hold it in place (and let some light in).  Phalaenopsis benefits from a humid environment around the roots, which can be achieved by standing the grow pot on a layer of something like lava rock or LECA in the decorative pot to support the pot, and keep that material moist.

orchid bowl schematic

Do not plant the orchid directly into soil or potting compost.

Ensure that the fleshy, grey aerial roots are able to sit above the surface and not get buried.  Let the grey aerial roots sit above the surface of the lava rock or LECA.  They are covered in a material called velamen, which acts like a sponge to absorb moisture from the air.

orchid aerial root and velamen

Heat and light

Orchids benefit from good light, but should not be placed in direct sunlight, draughts or near direct heat.  A minimum of 15°C is needed, ideally a little warmer once the flower stem starts to grow.  Large fluctuations in temperature between night and day will also shorten the lifespan of the flowers.

Orchids do really well in humid situations and make for fantastic bathroom plants.

Water

Orchids require regular watering, but must not be allowed to stand in water. My own research has shown that rainwater, or deionized (or distilled) water, with a little fertilizer (see below) is ideal, but tap water is acceptable in most circumstances (although it can vary, and often contains dissolved salts that can damage the roots).  

To water an orchid, lift its grow pot out of the decorative planter and take it to a sink.  Pour plenty of water into the orchid pot and allow it to drain, then replace into the decorative pot. If you keep the orchid on a layer of LECA, or similar, moisten that as well.  You probably won’t need to water more than once a week, or occasionally less frequently.  (If you are going to be away, give the plant a good watering before you leave and make sure there is some humidity at the base of the pot).  Standing water near the leaf bases will lead to rot and leaf loss.

Fertilizer

In their natural environment, orchids such as Phalaenopsis, gain their nutrition from the poor soil they grow in, or from water washed off the leaves of the trees that they live in (such leaf washings might include nutrients derived from dirt and even the droppings of birds, small mammals, tree frogs and insects).  In some species, bacteria or fungi live in the aerial roots and they are able to fix nutrients direct from the atmosphere.

Cultivated orchids require very little fertilizer, but some micronutrients are needed, especially when the plant is flowering.  Specially prepared orchid fertilizers are available from garden centres and orchid specialists, and whilst they may be beneficial, they are expensive and not absolutely necessary.  A weak (10% of standard rate) solution of a general purpose houseplant fertilizer (containing trace elements) mixed in deionized water is ideal.

Keeping orchids clean and pest free

Orchids are generally pest free, but mealybugs, scale insects and two-spotted (red) spider mites can attack them.  Remove any signs of webbing and mealybug egg masses as soon as you see them.  Aphids seldom attack the plant, but they may gather on the flowers, making them unsightly. 

Orchids have robust leaves and surprisingly strong flowers.  However, that does not mean you can be rough with them.  The most important thing to do is to remove any dust that has accumulated on the leaves – a damp cloth is often the best way.

Caring for the flowers

Phalaenopsis produces flowers on a long stem.  The buds develop at the tip of the stem and can be quite fragile.  It is important not to damage them.  Sometimes, the buds may not fully develop.  In this case, they will shrivel and should be carefully removed.  

Old flowers will start to shrivel, and these can be removed by gently rubbing the flower stalk from the stem.  Once all the flowers on a stem have finished, the stem should be cut back.  

If the plant is healthy and vigorous, it may be possible to encourage a second growth of flowers by cutting the stem back to just above the fourth or fifth bud where a new flowering stem can sometimes grow.  If the plant is lacking in vigour, the original stem should be cut right back to the base, and the plant allowed to recover.  

Flowering is triggered by a reduction in daytime temperature, so to get your plants to reflower, place them in a cooler (not cold, though) room in the house for several weeks before bringing them back to a warmer place.

As you can see, orchids really are pretty easy to look after, and they reward you with the most fabulous exotic blooms.  Once you have mastered Phalaenopsis orchids, why not try your hand at some of the more exotic types, some of which have the most enticing perfumes and even more glorious flowers.

(image credits: all images from author’s own collection)

By Kenneth Freeman

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