The ice flows
Virus-free foliage pelargoniums

Classic geranium disease-free at last

Pelargonium,zonal,geranium,Wren. Image © (all rights reserved)
I need to stop before I start, so to speak.

I was going to start by outlining the origins of this dramatic geranium – a zonal pelargonium, that is – but straight away I find that no one agrees. Was it introduced in 1949, the 1950s, or 1969? Was is found in California or Connecticut? Was it chance seedling, or a color break on a red-flowered plant?

There are, however, some things that everyone agrees about: The color is not only startling, but unique; it was found in the garden of a Mr. Wren; and it’s a tall and lanky plant which is a little shy in its flowering. Except I find even that is only partially true as Helen Van Pelt Wilson, in her book The Joy of Geraniums, from 1980, describes it as “very free of bloom”!

When I grew it I certainly found it tall and reluctant to make side shoots and so the overall floral impact was less impressive than I expected; I’d pinch it out but it produced hardly any side shoots, just a few tall stems that eventually needed staking. But it also produced these heads of dramatic flowers.

But things are changing. Thompson & Morgan have had the plant in the laboratory where they’ve removed the virus diseases with which it was infected. Here’s what Michael Perry of T&M, told me “We have taken the original stock of 'Mr. Wren' and further developed it to be slightly more compact and more freely flowering. As part of this process, we have also ensured it is virus-free, a problem with the older stocks.” They call it ‘Mr. Wren Improved’.

So at least it won’t pass viruses to other geraniums. This, by the way, is what was done with the colored foliage varieties that we now see everywhere; virus infection had greatly weakened them. With the virus removed they grow well.

And that red-and-white coloring? There’s a layer of red cells in each flower, sandwiched between two layers of transparent white cells. But the red cells do not extend all the way to the edge – so the edge is white.

I look forward to trying this new improved version of ‘Mr. Wren’ (so far only available in Britain, I’m afraid). I’ll report back on whether it really is more bushy.

In the UK you can order Pelargonium ‘Mr. Wren Improved’ from Thompson & Morgan.

In North America you can order Pelargonium ‘Mr. Wren’ (not improved, but still spectacular) from Trio Nursery.


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Mike Grant

And what do you think is meant by "and further developed it to be slightly more compact and more freely flowering"? Presumably it's the same clone that's been offered, not a seedling or something derived from further breeding. So is it the virus removal that has resulted in the improvement, or has there been some other process applied?

Graham Rice

My thoughts exactly, Mike. But I could get no more information. It may be, with the extra vigor of virus-free plants, that when pinched they branch more effectively. But if they're more vigorous wouldn't they also grow taller?

I remember one of Britain's top seed "geranium" breeders pointing out that it was pointless to try to breed from 'Mr Wren' as, being a chimera (with white petal cells overlaying the red), only the red coloring was passed down genetically. So they haven't done that.

My guess is that, whatever the change, it's all the result of the plants now being virus-free.

Graham Spencer

I won't rant about the correct use of the word "Geranium". :)

But, I suspect that the variation is down to clonal selection in vitro. In order to get virus free material, it is most likely that the plant was put into tissue culture (no mean feat with a chimera) and several ever-so-slightly different clones were produced. The "best" clone was then taken forward for production - and, if given a choice, I'd go for a clone that was shorter and bushier.

Of course, the plants might be virus free when they leave the nursery. That does not mean to say that they cannot become infected subsequently. So gardeners need to take a pinch of salt with your assertion that it will not pass virus to other varieties.

Graham Rice

Thanks Graham, that's really interesting and seems a very likely scenario. I made the remark about not passing on viruses because buying old varieties of zonal pelargoniums is a pretty sure way to introduce viruses to your existing plants and at least this shouldn't be infected when it arrives.

BTW, the name ‘Mr. Wren Improved’ is not a valid cultivar name. The International Code of Nomenclature for Cultivated Plants does not allow the word "improved" to be used.

Gwen Ward

I think Graham is right - the plant would have been put into tissue culture. I am sure T & M have done this with Pelargonium splendide. The one they sell and the one I have is very slightly different and, I am sure, not such a strong growing plant. I think if you buy your plant, whatever it is, from a reputable nursery, there should not be any disease. And I see they have stopped selling P. spledide as hardy here in the UK, but now 'over-wintered'.

Graham Rice

I'm sorry to have to say that nurseries that grow large numbers of different zonal pelargoniums, all propagated from cuttings, are often infected with virus diseases. That's why the Pelgardini program that took the viruses out of zonal pelargoniums with ornamental foliage was such a success. These viruses may not always be glaringly obvious - reduced vigor is not as easily spotted as the discolored leaves that viruses of other plants may produce.

B. Liddle

My geranium is siz feet seven and a half inches. Is it close to a record?


Graham Rice

The world record for the tallest geranium is 11ft 3in ( so you still have a way to go, Bruce.

B. Liddle

what is the recorded hight of a geranium?

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