There has been much discussion of the difference between the performance of this hybrid in New Zealand and in the UK.
The New Zealand plant has large 'cup and saucer' flowers which are pure red, but in Britain Vulcan has small flowers more like an opening hybrid tea rose than a magnolia, though larger and better formed flowers appear at the top of the tree as it gets older. Both, however, are a somewhat muddy reddish magenta pink.
The difference has been explained in terms of the climate.
This spring John Gallagher noticed two small trees labeled Vulcan growing in the Hillier arboretum near Winchester. One looked like the usual UK version, but one just like the New Zealand Vulcan. The trees are only a few metres apart, and are about the same size and age.
This seems to prove that most of us gardeners in the UK are growing a clone which is not the true Vulcan, and is quite inferior. The real clone, as can be seen from the photographs of the Hillier plant, is much more desirable, and performs almost as well in our climate as in New Zealand.
Nurseries need to replace the inferior clone with the true one. Caveat Emptor!
|the 'true' Vulcan at Hilliers, April 2003.
Photos: John Gallagher
|The typical 'Vulcan' available in the UK.
Photo: Mike Robinson
We were very surprised to read on your website a suggestion that there are two clones of Magnolia Vulcan in the UK, a conclusion
which seems to us to be based on rather slender evidence.
We certainly would not advocate anybody pulling out their Magnolia Vulcan to replace it with "the true Magnolia Vulcan". The photographs on your website certainly both appear to us to be Magnolia Vulcan, even if one is performing better than the other.
To the very best of our knowledge, there has not been a rogue clone of Vulcan slipped into cultivation in New Zealand and we doubt that it could have emanated from anywhere else.
Like any other magnolia, Vulcan is variable as a young plant and can take time to settle. We have observed the same pattern in New Zealand, especially where plants are not growing strongly. We were delighted to read that Hilliers at last have one performing well.
In our opinion the failure of Vulcan to perform well in the UK may be attributable to a number of factors of which a cooler climate, especially the cool summers, may be one. Soil conditions are the most likely inhibitor. Low Ph, low potash levels and a lack of humus will all bleach the colour out. There is a possibility that the rootstock may also have some effect although this is only conjecture.
We understand that soulangeana and liliiflora nigra can also show considerable variations in flower size and density of colour in different conditions.
We would not advocate removing an underperforming Magnolia Vulcan to replace it with another of the same - the second plant is highly likely to follow the same path as its predecessor. Our advice would be to add plenty of acid fertiliser and organic matter and to try and alter the soil structure to more favourable conditions. It appears that the stronger that the plant is growing, the better the flower.
Magnolia Vulcan was bred by Felix Jury here and we still have the parent plant and a number of other specimens on our property. All Vulcan material has originated from us.
If the two Hillier plants are seen as significant, then it is easy enough to chip bud one on the other and vice versa, to see if the budded material flowers differently.
Following observation of two very different neighbouring plants labelled Magnolia 'Vulcan' at The Hillier Arboretum, it was suggested that there are two clones of this cultivar in the UK, the one most often seen having inferior purplish flowers.
Magnolia 'Vulcan' (Barretts)
Following a visit to the Jury nursery at Taranaki, North Island, New Zealand, and looking at plants of Vulcan growing in diverse parts of that country last September makes me think that the real explanation is different. Mark and Abbie Jury are adamant that only one clone of M.'Vulcan' was ever released, but that it may be more variable than is usual with other Magnolia cultivars. Certainly the full range of flower size and colour could be seen in New Zealand, sometimes on the same tree. The biggest flowers were to be found mostly on trees growing on North Island (See photo: Barretts), and, although there were some superb flowers as far south as Dunedin, plants on South Island more often had the smaller less intensely coloured flowers that we see in the UK (see photo: Wyndham). The largest flowers on young trees, as in the UK, were to be found higher up (see photo: Wyndham 2).
|Magnolia 'Vulcan' (Wyndham)|
The flower colour seemed to be affected by soils as well as climate. The deepest richest red flowers were on plants
growing on the Jury nursery, where the rich volcanic soil has such a high iron content that it is almost magnetic, and there was considerable variation on
the flower colour in different gardens throughout New Zealand.
It appears therefore that the flower size and colour is greatly affected by three factors: the maturity of the tree; the soil; the climate. A warm climate with short winters and an iron rich soil seem to suit it best, but the very marked variation in the plants at Hilliers' remains a mystery. Perhaps one of these plants is not Vulcan after all. It is just conceivable that it could be the root stock often used by Duncan and Davies, which has now been named M.'Eleanor May' (see photo).
It would be interesting if gardeners growing Vulcan in Europe and the USA could share their experiences by contacting the RCM Group by post or e-mail.