A Northumberland Alpine Gardener's Diary
This entry: 13 February 2011 by John Richards
Northumberland Diary. Entry 172.
Effects of the hard winters
The last two winters have been the most severe for three decades, yet they could not have been more different, and now that we have settled into a rather unremarkable spell in the late winter, the time has come to assess their effects on garden plants.
During last winter, 2009/10, the freeze started in mid-December and gradually became colder and colder, lasting some nine weeks in total (here) and not relenting until mid-February. Plants were frozen into the plunge in the alpine house for two months. Not surprisingly, this resulted in a very late spring, and as I have related before, I suffered very many losses amongst my pot plants, principally bulbs. There was intermittent snow, but it lay to no great depth for most of the time and there was no physical damage to trees and shrubs. Crucially, the very cold weather (to -20c) arrived slowly, and after the plants had become fully dormant. Perhaps in consequence, there was almost no damage to supposedly tender evergreen shrubs and trees in the garden.
In contrast, the severe weather in 2010/11 arrived very early, on November 23rd and was characterised especially by repeated falls of deep and heavy snow over more than two weeks. This had calamitous structural effects on evergreen shrubs and trees that were not seen the previous winter. In my own garden, I went out of my way to knock fresh snow off on a daily basis, and structural damage has been kept to a minimum. Not so at the University Botanic Garden in Newcastle, which was inaccessible for two weeks, so that 30 cm of snow accumulated on evergreens. The effects were disastrous, so we have lost very many evergreens to breakage, loss of form (conifers especially being irreparably 'opened up') and we are still far from completing the subsequent clear-up. In particular, there will be many days of bonfires ahead. Parts of plants that were covered by the snow have largely survived, but there has been serious frost damage to the upper parts of many evergreen shrubs, particularly here at Hexham where it was even colder than it had been in Newcastle. Amongst those now completely dead above ground are my massive Crinodendron hookerianum, a 8 m Pittosporum tenuifolium (dwarfer ones have survived, and 'Tom Thumb' in particular is nearly unscathed), Drimys lanceolata, Desfontainea spinosa and Azara petiolaris. Almost equally interesting is what has survived almost unscathed. The camellias are untouched, as is Garrya elliptica (which is frequently cut to the ground). Olearia macrodonta, another frequently tender subject, is fine as are all rhododendrons (including 'Fragrantissimum') but excepting Rh. macabeanum. Several cistus are untouched, as is Arbutus unedo, but the Bay (Laurus nobilis) is damaged. Very hit and miss!
I am happy to say that another genus which seems to have survived unscathed both here and at Newcastle is Eucryphia. We only have a 6 m 'Nymnasay' here, but there is a comprehensive collection at Moorbank (the BG) and they all seem fine.
I am assuming that many of the plants that have been killed to the ground will come again from the base in due course. This has certainly been true for crinodendron after past episodes of cold; the fate of the others is not yet known. We are now starting to dispose of the corpses, which in some cases is a massive job, not least because we are now forsworn bonfires here at Hexham (unfair on the neighbours, and 'ungreen'), so everything is carried down to the waste disposal area in 'jiffy bags'. (But this uses petrol and so is also ungreen!).
As was the case for those areas that suffered the 1987 hurricane, every cloud has a silver lining of course, and the loss of overlarge subjects in a half acre garden presents super new opportunities for development. In the following photos, not only has the crinodendron been removed, but an overlarge and straggly Salix fargesii has been heavily pruned to shape, and a very large patch of Xanthorrhiza simplicissima has been reduced to less than half the area. The photos show 'before' and 'after' the crinodendron was removed, taken from about the same place.
Another notable feature of the present winter which contrasts so sharply with the last one is that the weather since Christmas has been chiefly unremarkable, and we are on course for a standard, even somewhat early spring, so that the Show Secretaries at Caerleon and Harlow have doubtless breathed a collective sigh of relief. Certainly there are quite a few early subjects 'strutting their stuff'' here at the moment, and as I said last week, the time has come to show a few.
First, a couple of irises at Moorbank. These are earlier than those at home, partly because the city is warmer, but also because they are planted up against the heated glasshouses! So here are Iris unguicularis, and that most persistent of the Reticulata irises, 'Harmony'.
In the same bed as the Algerian Iris, Scilla mischenkoana is pushing through the ground, its flowers already open when they reach the light.
I think I have shown the Hamamelis 'Pallida' there before, but I can't grow witch hazels here at home for some reason, and so treasure the Moorbank ones still further.
The photos of my garden above look sterile and winterbound, but there are drifts of snowdrops and aconites in many places. I have not checked which snowdrops I have featured in previous years, but I know that these two from the 'Castle Group' are new to this diary, because Ian Christie only gave them to me last year. They are quite as remarkable as Ian said they would be and deserve a short discussion. In 'The Rock Garden' 120: 51-52, Ian describes these plants and their origin (in the Crimean War) in detail. They are well-established at Brechin Castle, where they were planted by an ancestor of the present Lord Dalhousie. Interestingly, they are cared for at Brechin by another Ian Christie!! In the article quoted Ian (the first!) only mentions Galanthus plicatus and G. nivalis. When he gave them to me, he did discuss their identity however, and I would tend to agree that each of the eight rather similar plants he gave me seem to have some influence from G. elwesii as well as G. plicatus. The leaves are 2 cm wide, which is wider that Aaron Davis allows for G. plicatus, and the inner tepal maraks, while falling within the range of a few G. plicatus, are more typical of G. elwesii, as is the involute vernation. Early days, but they are much valued here as they seem to be thriving, and I struggle with most G. elwesii.
A plant I am fond of, and which seems to be a good doer here, I have christened 'Eslington Halfer'. Those of you who read my article on yellow snowdrops in the Plantsman 9: 48-51 will know that 'Halfers' (a name bestowed by the late Diana Aitchison) are probably genetic 'yellows' which are instead a pale khaki green, perhaps due to the influence of a modifying gene. They are only found in the Northumberland populations in which yellows also occur.
Galanthus 'Dionysus' is another very good doer here. One of the 'Greatorex' doubles, it is the biggest double I know of, early flowering and very weather resistant.
Another plant making a splash in the garden at present is Cyclamen coum. Here is a big clump that has sown itself into the base of the Liriodendron.
Several of my Primula moupinensis are being tended under glass, but here is a plant thriving in an unprotected trough. After all the rain it looks a bit weatherbeaten, but it does go to show what a good garden plant this is, definitely the easiest of the petiolarids here.
I did show one of the new raisings of Primula elatior subsp. meyeri in a pot in the alpine house during the hard weather. Another of the seedlings has now come into flower, and is perhaps even more stunning than the last.
The most awful thing happened yesterday, and has left me so traumatised that I am confessing it openly to all and sundry as some sort of therapy, or even exorcism. Also, there is a dreadful lesson to us all in the following tale, so I shall share it with you. I was due to talk to the local (Newcastle) Plant Heritage Group yesterday afternoon. Sure that I knew my destination, I blithely put a memory stick in my pocket and drove the 20 miles into Newcastle. When I got there, the Church Hall in question was not at all where I thought it was! I looked for my diary which had in it contact numbers and the destination address, and was horrified to find I had left it at home! I rang Sheila at home, only to discover that she had, very reasonably, gone out! By now it was time for the talk to start and all I could think of was to drive the 20 miles back to Hexham to get my diary. I finally arrived at the Hall an hour late, relieved to find that the efficient Chairman had had a spare talk in his computer, which was just finishing! As I apologised to the audience, I have never worse in my life. Moral, never go out without contact numbers and a destination address, however well you think you know an area!