A Northumberland Alpine Gardener's Diary
This entry: 05 June 2011 by John Richards
Northumberland Diary. Entry 185.
Know thine enemy
Now that this garden has reached its Maturity (its 21 years old!), it is, like many humans, starting to show signs of wear and tear. Indeed, I guess its downhill all the way from now on! In the winter and spring, while most of the weeds are still underground, it looks great, but by the time we have reached June I really need to admire the 'bones' through half-closed eyes if I am to ignore the rampageous growth of weeds. The problems have manifold origins. Chief amongst these has been my long-standing practice of building new beds from garden compost in which pernicious perennial weeds have not been properly killed. Also, although we both spend a lot of time gardening, quite a lot of it is spent at the Newcastle Botanic Garden, and much of the time spent here during the summer months is used to pot on seedlings, propagate young plants, and repot older ones. Two alpine houses take a lot of work, so the garden tends to become neglected in the summer.
Some areas of course remain in good condition. Increasingly, I grow 'difficult' alpines in containers, where they tend to be invaded by marsh orchids, but not much else. There are rock gardens, tufa beds and screes which remain largely weed-free, and which I work hard at keeping that way. But, by this time of year, much of the rest of the garden has been overgrown by a mass of unwelcome visitors.
Many of my worst problems were originally introduced as garden plants, but survive composting and have got everywhere. Number three enemy, perhaps, (I'll get onto nos 1 and 2 in a minute!) is the Mouse Plant, Arisarum probiscoideum, which forms thick, deep-rooted mats in any humusy soil. Other small plants cannot survive its strangling embrace.
Here is enemy number four, Cymbalaria hepaticifolia. This is one of a number of varieties of 'spaghetti' I grow, whose underground parts resemble a plate of pasta. Perhaps that April Fool by Richard Dimbleby all those decades ago wasn't so far off after all! (any younger readers, ask your Grandad!). In truth, the Cymbalaria probably does little harm except to the smallest subjects, but it gets in the way and looks unslightly, even if it is not unattractive in its own right.
Two other public enemies in the last photo won't get mentioned again, Ranunculus repens and Viola riviniana. Curiously, in this garden the latter tends to be worse than the former. However, these two depart from my theme, garden plants that went astray. Public nuisance number six is that lovely fern, a scarce native in the woods round here, the oak fern, Gymnocarpium dryopteris. Goodness knows why it is rare round here, as it is incredibly aggressive in the garden and it is almost impossible to disentangle the thin knotty black rhizomes from the root balls of rhodos etc. Many gardens do not grow ferns well, but they are a real nuisance here with lady fern Athyrium and male fern Dryopteris filix-mas sporing everywhere. My oak fern is much admired (and I have seen it greatly coveted on the Show bench), but I am waging a losing battle with it here!
'Cover your ground', the sages say! Well, plenty of ground-cover in this garden, but most of it is unwelcome! One last plant that was initially welcomed and is now persecuted (as am I by it!). I take full blame for the rash of cuckoo-pint (and many other faux-respectable English names) Arum maculatum, as I love the red fruits in late summer and allowed it to seed throughout the garden before I realised how persistent and deep-rooted it is, and how the leaves shade out less vigorous congeners.
Rhododendron keleticum was having a bad time in the last picture, symptomatic of many of the problems here.
Also, into the last picture has strayed a wisp of public enemy no. 1!! Unlike those mentioned so far, this was not introduced as a garden plant, and I doubt if it is serious weed in many other gardens (although I know Alan Furness, three miles from here, finds it troublesome). What is it? Well, it is Vicia sepium, the bush vetch. This, another branch of the spaghetti kingdom, is incredibly aggressive here, travelling vast distances underground, to flower and seed over six months, and with a dreadful tendency to appear right in the middle of other plants (including cushions) which it then proceeds to strangle very quickly. It is impossible to remove physically (bits always remain behind and grow again within days), goes to seed very rapidly, and seeds disperse great distances (I am not sure how) to grow in any circumstance. This is a plant that grows with great vigour anywhere, in the centre of the densest shrub, in the sparsest of screes, between pavings, anywhere!!
Public enemy no. 2? Well, you will not be surpised to learn that it is ground elder (bishop's weed), Aegopodia podagraria. We did not really have this when we arrived, but it was next door and in the hedge, and despite rigorously deadheading any flowering bits on this side, seedlings appear with depressing regularity, and it is very difficult to get rid of every bit. I have now virtually abandoned the bed nearest to the infected garden (well, the early and late bulbs are good!), but elsewhere we keep on top of it, having taken it very seriously ever since we came here. In fact, it is not as serious a weed as the vetch, but only because I can control it, but have no idea what to do about the vetch!
Not all unbidden visitors are unwelcome however! The commonest wild orchid round here is the Northern Marsh Orchid, Dactylorhiza purpurella. Orchid seed is very light and flies great distances through the air. Not long after we came here, we covered the poorly paved sunken patio with about 2 cm depth of gravel and this has turned into a marvellous seed bed, as plants root into the cracks between pavers (protected from dessication by the gravel). Some years ago, a plant of D. purpurella appeared spontaneously, and has now formed a nice clump.
A few more plants that are at their best now. Firstly, by far the most successful celmisia in this garden, C. allanii. Once, I grew quite a large number of New Zealand daisies, but lost most of them in a short but extremely cold spell in January 2001 when the mercury dropped to well below -20C in the absence of snow, and rather lost my enthusiasm as a result. C. allanii is a super plant throughout the year, and is very easily propagated from ''sticking in' dutch cuttings (slips with a modicum of root) during any damp spell.
Sheila's perennial bed is enjoying its first main flush of colour. Aquilegia vulgaris, Papaver orientale, Thalictrum aquilegifolium and Euphorbia griffithii are conspicuous (and Russell lupins!).
I am delighted to welcome a flower on a plant grown from wild Chinese seed last year as Gentiana arethusae. The seedlings were put out last autumn into a fishbox in a gritty mix in full sun and overwintered without protection. On Googling G. arethusae I can find nothing, but the AGS Encyclopedia has it as a synonym for G. hexaphylla, and as far as I can see it must at least be a close relative. If the flower opens I shall post it again!!
Now that I have more or less finished pricking out the seedlings (about 500 from 85 or so subjects), I have been busy over the last couple of days repotting some of the plants in the alpine house, now that the two-day heat-wave has subsided (we recorded 29C in the shade on Friday, but it was only 15C on Saturday!). Himalayan primulas, meconopsis and other susceptible subjects looked half-dead on Friday but made an instantaneous and complete recovery once the weather cooled.
There are still a few interesting subjects flowering under glass. The two dwarf Greek daphnes, D. sojaki, from Vermion, and D. jasminea, from Delphi are flowering together and showing a considerable resemblance, although the foliage of the former is much more robust. The similarity is surprising in one way, as the two species have quiote dfferent ecologies, D. jasminea being a strict chasmophyte of low altitudes, while D. sojaki lives in rocky alpine pastures at about 1800 m. Possibly both have evolved from the much more common and widespread D. oleioides. As I have noted before, D. sojaki bears some resemblance to the little-known Croatian D. malyana.
Here is another shot of D. jasminea.
I have been very impressed by the toughness of the South African Zaluzianskya ovata. I took cuttings from a moribund plant last summer and put them in a shady place, pricking them out into separate pots when they rooted in the autumn. These were put in the plunge of the unheated alpine house last winter, which suffered extremely low temperatures (certainly -15C) for several weeks and a lot of supposedly hardy subjects were lost. But the zaluzianskas sailed through and were repotted or planted out in the spring, where one is flowering well outside at the Botanic Garden. Here is one in a pot at home.
Talking of the Moorbank Botanic Garden (University of Newcastle) which we help to run, here are a few plants that thrive there, but we do not grow at home. Firstly, that nice white Caucasian gentian G. gelida, raised from Holubec seed.
An amazingly gaudy Lewisia cotyledon variety. We can't grow this at home, but in the drier warmer climate of Newcastle it thrived without protection.
Anemone rivularis. This petered out at home, but persists well in Newcastle.
Finally, we have enjoyed putting robust summer-flowering 'bulbs' into the hay meadow at the Botanic Garden, where a number of them show signs of settling down. Earlier there are Fritillaria meleagris and Narcissus poeticus in quantity, and later a good stand of Lilium martagon. At present, Gladiolus communis and Iris xiphioides are brightening the scene.
Just to say as an addendum that we are off on our travels next week, so this is likely to be the last posting for a month. Talk to you in July!