Alpine Garden Society

Ulster Group

         Plant of the Month, March 2007

Pleione 'Vesuvius'  by George Gordon

Pleione "Vesuvius"

The Family Orchidaceae is one of the largest in the world, represented in Ireland alone by between twenty and thirty species. However we have nothing like the Genus Pleione. At first sight it might seem that the showy flowers hint at a hothouse culture, but this would be wrong. In the wild Pleiones are woodland plants growing from India eastwards across Asia to Taiwan. 
They are at least semi-epiphytic, growing on mossy branches and rocky ledges, where presumably the deciduous pseudobulbs are not eaten by the equivalent of mice (the only predator I know here which attacks them in a pot). 

They can also grow up to a considerable altitude (4,000m). In the context of the European Alps this would be at the permanent snowline, but on the scale of the Himalayas we are still below the tree line. They are however cold and at least light frost-hardy, and I know one garden here where some stay outside all year. In these conditions however they do not thrive, and it is best to grow them in pots. The pseudobulbs are deciduous, and unlike the majority of say Narcissus bulbs, the dry period they like is in late autumn and early winter and not in summer. This is best accommodated in pots.
So how do we set about cultivating them? Over the years I have tried many compost mixes, some quite exotic. I have simplified this down to a few basic ingredients that can easily be acquired - perlite and composted bark (B&Q stock both). The pots stay outside most of the year in a shaded part of the garden, but are taken into the garage for a dry rest in November, when all the leaves have died back.

I start the Pleione year in late January (any time up to early March would do) by emptying out the pots and tidying up the pseudobulbs - the old ones die every year but produce at least one new flowering one (often two). The old roots are cut away. One point to be careful with is the bud at the side. This is the new flower bud and disaster can be avoided by careful handling. I also take the opportunity to sort them out into flowering (these are easy to tell by the flower buds) and non-flowering sizes. Small bulbils are also kept aside to give away or put into the AGS Seed Exchange.

I do not use a half pot for Pleione "Vesuvius" as it has a vigorous root system. I use 16cm plastic pots, which have plenty of drainage holes. To improve this I put in a layer of rockwool at the bottom, but cotton wool would be equally good; this insures perfect drainage and also stops the compost being lost. The mix is two-thirds composted bark and one-third perlite. If I had access to good leaf mould I would increase the content of perlite to half and half, but good leaf mould is hard to come. The pot is filled to a few inches from the top, and the pseudobulbs gently firmed in but not buried. I leave about the half the width of the pseudobulb all round, but only to appreciate the flowers more and not because they dislike being crowded. I top dress with moss, which my wife Pat gathers from the garden (she is the artistic one). If all this seems complicated you can rest assured that almost all the work is finished, and very little extra attention is required for another year.

These pseudobulbs will now flower before the roots or leaves are produced, as the flowers were formed over the previous summer. Do not water the pots, as there is enough residual moisture in the compost. The only water I give is by spraying the moss, and it is surprising how much it can absorb. I keep the pots in the conservatory, but a windowsill would do. They will flower in about six weeks. After the leaves appear you can water more freely, and by the middle of May I leave the pots out again in the garden. A weak feed of tomato fertilizer is given, but they are not greedy feeders, nor are they prone to disease as far as I am aware. Even the odd mouse attack is desultory (they are not to their taste).

All the Pleiones I have came from the generosity of friends in the Ulster Group. They regularly appear on the plant stall as either pots or bulbils (which are usually given away). The cultivation of bulbils is the same as above except I use a half pot. Susan Tindall has a selection at Timpany Nurseries near Ballynahinch ( Bulbils also appear in the AGS Seed List, but you have to be quick to get them. I have never bought any from the specialist growers, but they are listed in the RHS "Plantfinder" if you are interested.

One word on nomenclature. The names I use are the ones I received when I was given them, and I have no easy way of checking them. I know some have been misnamed now. Quite a few of "Vesuvius" ilk have been named after volcanoes. It is still a good pot plant that requires little attention and rewards the little effort expended.

So have a go yourself. In a few years, hopefully, you will be thanking me for the delight these orchids bring in early spring.