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#1
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cultivated rhododendros : spreading threat?
Is there any need for alarm? We used to have six massive rhododendron bushes in our front garden that produced a wonderful wall of colours about this time each year. Over the course of many years, never once did we find a little rhododendron sapling growing anywhere else in our garden, or for that matter in the surrounding fields. Those rhodies simply never spread - despite our garden and all of the surrounding land being highly acidic, quite temperate, and ideal for the growing of rhodies.. Then we moved house about three years ago and missed the wall of the colour, so we planted a dozen small cultivated rhododendrons purchased from a local nursery. Along comes a neighbour yesterday with fear writ large all across her brow and she warns us we had better cut every single flower off once the petals have fallen OR there'll be rhododendrons everywhere and local farmers will be furious with us! There are no other rhododendrons in gardens in this area, though largely, I suspect, because most of this area is more alkaline than acidic. We are fortunate in that our little patch is quite acidic. Could it be that the fear of cultivated rhododendrons in this area has resulted from the fact that people can't grow them here and are ignorant of them? Have done a brief google on this subject and found that "Rhododendron ponticum" can spread. Thanks. Eddy. |
#2
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cultivated rhododendros : spreading threat?
In article ,
Eddy wrote: Along comes a neighbour yesterday with fear writ large all across her brow and she warns us we had better cut every single flower off once the petals have fallen OR there'll be rhododendrons everywhere and local farmers will be furious with us! There are no other rhododendrons in gardens in this area, though largely, I suspect, because most of this area is more alkaline than acidic. We are fortunate in that our little patch is quite acidic. Could it be that the fear of cultivated rhododendrons in this area has resulted from the fact that people can't grow them here and are ignorant of them? No. It's a result of the media hysteria. If rhododendrons don't grow well locally, they won't naturalise - and acidity is only one of the factors that they need. Outside SOME parts of the far west, and a FEW parts of the south, even R. ponticum will have trouble when faced with real competition. Despite claims, its spread is NOT limited by the fact that "it hasn't got here yet", but by the fact that it won't spread to the relevant locations. Regards, Nick Maclaren. |
#3
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cultivated rhododendros : spreading threat?
"Eddy" wrote in message
... Is there any need for alarm? We used to have six massive rhododendron bushes in our front garden that produced a wonderful wall of colours about this time each year. Over the course of many years, never once did we find a little rhododendron sapling growing anywhere else in our garden, or for that matter in the surrounding fields. Those rhodies simply never spread - despite our garden and all of the surrounding land being highly acidic, quite temperate, and ideal for the growing of rhodies.. Then we moved house about three years ago and missed the wall of the colour, so we planted a dozen small cultivated rhododendrons purchased from a local nursery. Along comes a neighbour yesterday with fear writ large all across her brow and she warns us we had better cut every single flower off once the petals have fallen OR there'll be rhododendrons everywhere and local farmers will be furious with us! There are no other rhododendrons in gardens in this area, though largely, I suspect, because most of this area is more alkaline than acidic. We are fortunate in that our little patch is quite acidic. Could it be that the fear of cultivated rhododendrons in this area has resulted from the fact that people can't grow them here and are ignorant of them? Have done a brief google on this subject and found that "Rhododendron ponticum" can spread. Thanks. Eddy. Most of those big'n'blousy rhodos are hybrids that set little or no viable seed. They won't spread. Even the true species (other than ponticum) aren't particularly efficient at spreading by seed in a short time. The main thing to remember with some rhodos is that they "poison" the soil beneath them and make it very difficult for other plants to germinate their seeds or get established once they have germinated. As to people's fear of cultivated rhodos, why add "of them" at the end? ;-) -- Jeff |
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cultivated rhododendros : spreading threat?
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#5
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cultivated rhododendros : spreading threat?
Thank you very much, Janet, Sacha, Nick, Jeff, and Stewart! If our cultivated rhodos at our other place had gone and caused saplings to pop up all over the place, I guess we wouldn't even have considered growing them here. But confronted with the "authoritative" announcement of yesterday I was totally unprepared and taken aback. I didn't even remember in that instant that the rhodies at our previous address had caused no bother. Now we shall carefully consider which member of this community to advise that experienced horticulturalists (all of you!) have assured us there is no problem and then, fingers crossed, the message will be passed around! Perhaps we might then see one or two rhodies popping up in other gardens. Thanks again. Eddy. |
#6
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cultivated rhododendros : spreading threat?
The main problem with rhododendrons is that the hybrids that you
purchase in most nurseries are propagated by grafting on to ponticum. The result is that the ponticum takes over unless they are carefully watched. I would always when buying rhododendron hybrids to ask the seller whether they are grafted or propagated on their own roots. My advice is to REJECT GRAFTED HYBRIDS. Regards Don |
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cultivated rhododendros : spreading threat?
Donwill wrote:
The main problem with rhododendrons is that the hybrids that you purchase in most nurseries are propagated by grafting on to ponticum. The result is that the ponticum takes over unless they are carefully watched. I would always when buying rhododendron hybrids to ask the seller whether they are grafted or propagated on their own roots. My advice is to REJECT GRAFTED HYBRIDS. Regards Don Many thanks for this interesting info, Don. I've just rung the nursery where I bought our rhodies and asked them whether their rhodies are grafted onto Ponticum or propagated on their own roots and they have assured me that all of the rhodies they sell are propogated. So that's a relief. But, just out interest, when you say that in the case of grafted rhodies the ponticum takes over "unless they are carefully watched", what do you mean by the "watching"? What is it that one can do in such cases to stop the Ponticum taking them over? When I begin instructing those in this area who live in fear of all rhodies, it would be good to be armed with this knowledge as well and to be able to speak with what may come across as real expertise! :-) Thanks. Eddy. |
#8
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You have to do similar with roses which are often grafted on to more vigorous wild species. Or pear trees which throw up quince shoots from the base. |
#9
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cultivated rhododendros : spreading threat?
On 28/05/2010 10:54, Eddy wrote:
Donwill wrote: The main problem with rhododendrons is that the hybrids that you purchase in most nurseries are propagated by grafting on to ponticum. The result is that the ponticum takes over unless they are carefully watched. I would always when buying rhododendron hybrids to ask the seller whether they are grafted or propagated on their own roots. My advice is to REJECT GRAFTED HYBRIDS. Regards Don Many thanks for this interesting info, Don. I've just rung the nursery where I bought our rhodies and asked them whether their rhodies are grafted onto Ponticum or propagated on their own roots and they have assured me that all of the rhodies they sell are propogated. So that's a relief. But, just out interest, when you say that in the case of grafted rhodies the ponticum takes over "unless they are carefully watched", what do you mean by the "watching"? What is it that one can do in such cases to stop the Ponticum taking them over? When I begin instructing those in this area who live in fear of all rhodies, it would be good to be armed with this knowledge as well and to be able to speak with what may come across as real expertise! :-) Thanks. Eddy. I'm not an expert Eddy, however, ever since I became interested in gardening I 've been aware of the dangers of buying hardy hybrids from nurseries by reading favourite books on the subject. Ref -Michael Howarth Booth (MHB),The Flowering Shrub Garden, 1947, P59, "Nursery bought plants are usually grafted on R.Ponticum, which will cause endless trouble with suckers unless the bushes are planted about 4 inches deeper than before,with peat, only, put on to cover the roots up to within 2 inches of surface level, and finally a mulch 6 inches deep of leaves or June cut bracken, put on over all." Ref - MHB, The flowering Shrub Garden Today, 1961, P77. "When a bed is planted up solely with grafted hybrid rhododendrons, the whole thing is apt to be overdone so that we get an overpowering concentration of flowers at one time and an unrelieved hump of dark green for the rest of the year. Culturally it is disastrous, for rhododendron fly and bud blast run riot through such mono-cultures, the ponticum rootstock smothers the scions unnoticed and eventually a vast dark catacomb beneath high straggling branches leads to the whole thing being sooner or later felled to the ground. The ponticum, then,almost alone survives" P78.- "if grafted, ponticum suckers are promptly spaded off." Ref - Cox & Cox, Encyclopaedia of Rhododendron Hybrids, 1988, P10. " due to the use of the over-vigorous ponticum being used as a rootstock to graft most hybrids, the rootstock usually throws vigorous suckers which if left unattended soon smother and kill the hybrid grafted on top." I've extracted a few ref's above, MHB recommends spading the suckers off, I'm not sure if that's a bit drastic, however you could I suppose treat them like rose suckers, either you cut or pull them off. I've always planted them a bit deeper than normal, and as an insurance, any convenient low branch I have layered by abrading the bark and placing a stone on it to press it down into a bed of acid compost . Hope this helps Good Luck. Don |
#10
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cultivated rhododendros : spreading threat?
Jeff Layman wrote:
"Eddy" wrote in message ... [...] Have done a brief google on this subject and found that "Rhododendron ponticum" can spread. Thanks. Eddy. Most of those big'n'blousy rhodos are hybrids that set little or no viable seed. They won't spread. Even the true species (other than ponticum) aren't particularly efficient at spreading by seed in a short time. See SRH's comments, authoritative as usual. I'll add my agreement about R. ponticum's fairly modest rate of increase in any but the most ideal conditions. Back in West Wales we had them along our little stream, on a pretty neutral soil. I wish I'd taken notes, but I made a crude estimate of the age of the oldest (about a hundred years), and, IIRC, deduced that there may have been no more than about one or two surviving seedlings per annum. The fields on either side had been stocked for all that time, so I assume that poaching would have put paid to any seedlings which tried to extend outward from the stream. An old group near the house made a delightful den for the children, with the stream running through. [...] -- Mike. |
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