French garden diary – Orchids

Science behind orchids’ triumph. Cathy Thompson on micro-propagation plus how to care for indoor beauties

25 December 2019
One of the problems encountered with orchid breeding was that orchid seed is difficult to germinate
By Cathy Thompson

Have you ever asked yourself why orchids are so continuously – and cheaply – available in our supermarkets these days?

It is a far cry from my earliest experience of them – expensive, difficult to grow and very, very easy to kill.

But the orchids that many gardeners were experimenting with in the 20th century are light years in breeding away from those we can grow now.

The wide range of Phalaenopsis, or Moth Orchids, available is perhaps the most startling innovation.

Gone the days when you needed an expensive, shaded glasshouse heated consistently to between 18 and 21°C; failing that, an indoor terrarium, providing the continuous warmth and moist atmosphere they prefer, while avoiding  saturating and rotting the roots.

Thanks to breeding programmes, we have a range of hybrids that are longer flowering, longer living and much more tolerant of drier conditions in the home.

One of the problems originally encountered with orchid breeding was that orchid seed, although abundantly produced, is difficult to germinate.

Along came the scientists who discovered that, unlike the acorn – a natural packaging that has the ability to supply a young seedling with nutrient in the earliest days of growth – orchids have no such reserves.

They rely on association with a microbial root fungus to initiate growth.

The next step was analysis of the trace elements and chemicals released by that fungus – and the development of a synthetic solution which would promote orchid germination. Modern orchid nurseries are now indistinguishable from a science lab.

But, in 2020, we do not owe those millions of Moth Orchids to seed-raised plants.

Yet another scientific advance led growers deep into the world of micropropagation – the production of clones of the best (most living-room tolerant) cultivars from just a few cells.

The ‘perfect orchid storm’ arrived with the fluctuating fortunes of Taiwan’s sugar cane industry.

The government began to offer financial incentives for growers to diversify and small-scale businesses focused on breeding orchids were enabled.

Geographical separation of production facilities and market might have presented a barrier to export.

Since Moth Orchids do not produce water-storing ‘pseudobulbs’, like some other orchid genera (think Cymbidium or Dendrobium), they are notoriously difficult to transport.

But with the techniques of micro-propagation, young plants could be raised in Taiwan and China and shipped abroad in tiny glass jars that contain everything to survive a potentially stressful journey.

Now a huge percentage of the world’s Moth Orchid crop is raised by micropropagation specialists in the Far East and shipped back to the Netherlands to be grown on.

But it is easy to buy something in flower and then simply to discard it when it no longer thrives. That is not growing, it is consuming.

Although modern varieties are tougher, it still pays to understand what a Moth Orchid loves best.

Most modern types come from species originating in the Philippines.

They enjoy a constantly moist atmosphere and little direct light in their forest homes, where they are epiphytes.

In the wild their roots attach themselves to the bark of the tree and run along it for some distance – they do not take their nutrients from the tree itself, but from the build-up of debris in the tree’s branches, or in the forks of the orchid’s own root and stem system.

One or two new leaves are produced from the centre of the plant in a season and your average plant may have between three and six leaves at the same time.

In cultivation the roots will adhere to anything they come into contact with, both for moisture and nutrients.

You can add these different factors up and conclude that in fact a terrarium (or at least an association of several plants together on a gravel-filled tray kept continually moist) is the best option.

The water balance is crucial. Too wet is as bad as too dry. I used to mist my plants over several times a day – and then they developed leaf spotting and roots that began to rot.

So do go ahead and mist them, but no more than once a day in hot weather, once a week in winter.

Moth Orchids have no definitive flowering season, so are always available in the shops, but tend to flower less in winter.

It is after the peak of flowering has dwindled a little that they produce more leaves. Beware if you have a Moth Orchid with only one leaf, since it is doomed to die. The new leaves always have to appear in the centre of an existing leaf pair.

My conclusion? They are more tolerant as houseplants these days, provided they have a temperature of no less than 180°C and reasonable atmospheric humidity.

They do live and flower for a long time. But those beautiful, life-supporting grey and olive-green roots are not easy to please. Perhaps you need to plant a tree in your salon as well? Just to keep your Moth Orchid happy for life.

 

Over to you …

What’s your favourite houseplant? Do you have any special tips for growing orchids in the home?

You can contact Cathy by email at editorial@connexionfrance.com

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