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A Northumberland Alpine Gardener's Diary

This entry: 17 June 2008 by John Richards

Limestone pavement at Sunbiggin Tarn, and meconopsis. Entry 78.

Cracks in the pavement
On Sunday we led a Northumberland Natural History Society outing to Sunbiggin Tarn in south-east Cumbria, centre of the old Westmorland. I first knew this area 45 years ago when as a Durham University student our lecturer David Bellamy took us there for a couple of weekends. In those far-off days the area was unprotected and there was free access, but now most of the tarn fringe is fenced, and the water is stocked and fished . Perhaps as a result the massive gull colony has vanished, probably a good thing, and many of the other breeding birds are more scarce, but we did see breeding water rail, wigeon and reed warbler.

Cracks in the pavement

What has this to do with alpine gardening? Well, as you see this is a montane area (at about 400 m altitude), but more to the point, the Tarn is surrounded by some of the best stretches of limestone pavement in northern England. Pavement is a curiouslynorthern English, Welsh(and Irish!, the best development of allis found on the Burren around the Galway Bay) phenomenon which demands thick deposits of hard jointed Carboniferous limestone, a recent glacial history, and a mild, wet Atlantic climate. Most pavements would have been forested originally, and a few still are, especially around the Morecambe Bay, but heavy sheep grazing has reduced most to the bare platforms shown below, where the forest plants now find the low light and humidity they require deep in the 'grikes', the deep vertical joints in the limestone.

It is amazing what you find in the grikes. One might have a perfect little bonzaied ash tree, or a hawthorn or a rowan. In the next might be a gnarled plant of ivy, a patch of nettles, or dogs mercury, or willow herb. But there is a special flora of these areas too, and many of the rarer plants are ferns. In the first photo we see the green spleenwort, Asplenium viride, growing with the commoner hartstongue fern, A. scolopendrium and a small piece of wall-rue, Asplenium ruta-muraria (the flowering plant is herb robert). In the second is the rare limestone male fern, Dryopteris submontana. All these are good garden plants that appear in fern classes in the Shows, and can be obtained from specialist nurserymen (they should never be removed from the wild!).

Royal flush

Until fairly recently, these rare plants, and indeed the whole remarkable pavement community, was gravely threatened by the removal of thissurface pavement for 'rockeries', and many are the Council-designed park features and roundabouts that feature 'water-worn Westmorland limestone'. I am happy to say that all pavement in this country is now protected by law, and I believe I am right in thinking that it is even illegal to sell or buy this stone.

I admit to some mild hypocrisy here. When we arrived in the present garden nearly 20 years ago we discovered 10 tons of Westmorland limestone already in position, purchased many years ago by a former owner (and then inexplicably buried in a dense mat of Hypericum calycinum, 'rose of sharon'). This can hardly be returned to the wild, so we have embraced this serendipitous discovery with some enthusiasm. Few garden owners are so lucky.

Another of Sunbiggin's engaging features is a large series of spring-fed flushes, rich in dissolved calcium bicarbonate from the limestone. In the past these have formed hummocks of living tufa, but the tufa formation is much less impressive now than I remember from 45 years ago. I need hardly say that this tufa is also strictly protected, not that it would be of any use to the alpine gardener anyway.But it does give an idea as to how the deposits from Bodfari, Derbyshire, and elsewhere that can still be purchased for the purposes of rock gardening originated.

Today, these flushes contain a rich flora, in which Primula farinosa is conspicuous. Indeed this must be the premier localitiy in the country for this primula, which occurs in countless millions. There are also large quantities of marsh orchids, Dactylorhiza. In the following photos the pinkplant is D. incarnata in its subspecies incarnata, also with some of the purple subspecies pulchella, and the larger purple plant is D. purpurella.

Royal flush

This is a good place to return to the garden, for Dactylorhizas feature here too. Curiously, those I have introduced (rather expensively) have not flourished, but native species have arrived on the wind, and have colonised the garden, and especially the trough area, on their own accord. Interestingly, the trough shown here was only established a year ago. Of course, seed-sown seedlings of the orchid (which are hybrids between D. purpurella and D. fuchsii) might have established in the saxifrage cushion before it was moved to its present location.

Now for a far more exotic orchid. When Michael Myers visited our group in April he brought some imported, commercially raised, disas from South Africa. They were unnamed, but some seemed to be flowering size, and at 5 they seemed very reasonably priced compared to most orchids. I potted mine in a smallish clay pot in an 'orchid compost' of my own devising (shredded sphagnum, vermiculite, leaf mould and ericaceous compost all featured) and since then most watering has been with rain water, and rather infrequent. Initially, while frosts threatened, the plant lived in the conservatory, but for the last month it has graced the alpine house and it has now consented to flower. It is clearly the 'Pride of Table Mountain', Disa uniflora, a plant which is said to be pollinated by only one butterfly species 'the Mountain Pride'. Having said this, my excellent book on South African butterflies has no mention of this butterfly; I think it is properly the 'Protea Emperor', Charaxes pelias, a relative of the Two-tailed Pasha from the European mediterranean.

Whatever, this is some spectacular orchid!

Seedling spectacular

I have now finished pricking out this year's crop. On the whole I have been quite pleased with the results. In all, more than 65% of the seed sown this year germinated. Not all have been pricked out of course. Bulbs and some other subjects have been left in the seed pot to grown on for a season, but I have potted on more than 70 subjects into more than 500 containers, and more than 430 have survived the vicissitudes of chance, drought, predation, (and in some cases donation to friends).

At this stage, most sit in trays without protection. In dry spells they are watered with a hose (with a rose giving a light spray) and they are fed with dilute tomato feed every two weeks or so. Although in full light, the area is humid as it lies directly below an alpine house and the self-watering system overflows onto the gravel on which they stand. Only a few subjects, mostly petiolarid primulas such as P. sonchifolia and P. moupinensis, are grown in more shade at this stage.

Indeed, the theme I wish to explore is how tolerant young seedlings are. At this stage, all they seem to need it adequate water, humidity, light, food and drainage, and even the most tricky subjects flourish. It is later on, when they reach adolescence, that they become more choosy. Sounds familiar? (!). Here are photos of young plants of Meconopsis delavayi (from the Meconopsis Group seedlist by the way!) and Primula bracteata, seed from Geoff Rollinson. Later on, both will need very special attention, but at this early stage, all they seem to need is TLC.

Seedling spectacular

I am enjoying Calceolaria uniflora in the alpine house at present. This is a plant that I don't seem to lose, but cannot get to Show condition, as it is forever dying off in patches. It is a martyr to aphids, and also red spider under glass, but it seems even more difficult outside and only survives for me in the alpine house, grown in a plastic pot.

Blue heaven

Finally, a bevy of meconopsis. What came as M. latifolia has flowered at Moorbank Botanic Gardens. The two seedlings here have not flowered this year, but look happy. Is this M. latifolia? It clearly is not M. betonicifolia, but doesn't seem bristly enough for the former? Comments would be welcome.

Blue heaven

That photo also had M. racemosa of varying colours in it. Here it is again, this time in my garden.

I received this plant as Meconopsis 'Slieve Donard'. The contingent from Northern Ireland that were here on Thursday were very dubious. They should know! So what is it? Again, contributions welcome.

I think the identity of this final subject should be less controversial as I grew it from seed, so it must be Meconopsis 'Fertile Blue Group', aka (more or less) 'Lingholm'.

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