A Northumberland Alpine Gardener's Diary
This entry: 03 April 2013 by John Richards
Northumberland Diary. Entry 240.
Here we are, first week of April, and crocuses are just coming to their best, at least a month late! What a dismal spring it has been! We have actually been brightly sunny today, and scraped into double figures, 10C, whereas my daughter tells me that it is 4C and freezingly gloomy in Hertfordshire. Who says it is worse in Geordieland? (Well, it probably is, most of the time).
Some really worthwhile garden crocuses to start with. In fact, some have finished, the two C. sieberi clones I grow for instance, most of the (rather few) C. herbertii, and most of the 'tommies' (C. tommasinianus). A few of the latter survive in cool shady places where they had not been able to open until it was warm enough. Some of the later ones have silvery backs to the outers.
There are a few of the named varieties here, notably 'Whitwell Purple' which is probably hybrid in origin as it does seem to flower a bit later than most so-called 'tommies'.
The white form, probably just 'var. albus', also seems a little later to flower, and less vigorous than the wild type, although it too has nearly finished.
Perhaps the best garden crocus here is 'Violet Splendour' which increases very well and sows about, apparently staying true. I acquired it as a form of C. sieberi, but it is probably closer to C. vernuus and C. tommasinianus, although in truth these three species are very closely related. Probably it is best quoted as a cultivar without species assignation.
Outside, the C. chrysanthus/biflorus hybrids staggered on for many years, but have now finally nearly disappeared. They don't persist as well here as the vernuus crowd, needing more heat and better drainage. One of the few survivors is 'Blue Pearl', seen here with a well-budded Erythronium hendersonii.
As for C. vernuus itself, we have a lot of the big 'Dutch' polyploids, some of them named forms such as 'Pickwick'. Here is a straight imperial purple, quite like 'Violet Splendour, but grosser and blowsier. These were in the garden when we arrived, together with some white ones.
Then of course there are some yellows, also an introduction from before our time here. I guess these are the usual C. flavus x angustifolius hybrids. The dark stripes on the outside of the tube separate them from the neater pure C. flavus, which I think we also have.
Staying with crocus, but moving into the alpine house, several species are flowering for the first time. In fact I had pictured C. kosaninii before, but more flowers have now opened, and it is basking in the sunshine.
The factors that cause crocus flowers to open are interesting, and not well known. The trigger than causes the flower to open is the temperature inside the base of the flower, which needs to be in excess of 11C. However, in bright or sunny conditions, the flower may open in much cooler weather because the closed flower acts as a 'greenhouse', permeated by incident energy (as light), which is then disapated as heat energy which is trapped within the closed flower. This explains why many species (e.g. C. sieberi) have a pale 'window' at the base of the flower or in the tube. This 'greenhouse effect' then stimulates the flower to open even if the ambient temperature is well below 11C.
Thus, it was only when the sun finally reached the alpine house that the flowers of that wonderful bog crocus from north-west Greece, C. pelistericus, opened. These plants were grown from seed gathered on Kajmatkcalan during the MESE expoedition in 1999. The plastic pot is stood in water in the growing season to mimic wild conditions, but is kept rather drier in winter.
A final crocus, another Balkan species, C. malyi, flowering for the first time from Gothenburg seed sown in 2004! And only one flower too! I must confess that the seedlings have suffered some rough conditions, not least two very cold winters which finished off most of my bulbs in pots, and these may have knocked them back.
More bulbs' flowering for the first time are a series of Hepatica nobilis, grown from seed gathered just outside the Garda mountain village of Magasa in 2009. The seed was sown fresh as soon as we got home, green in fact, as I think is best for most Ranunculaceae. They are a fairly standard dark blue, but bonny enough none the less.
The hybrid H. x media 'Ballardii' is flowering in the main garden in several places.
A new saxifrage hybrid to me, acquired last spring, is 'Allendale Host', raised by Ray Fairburn who lives only about 10 miles from here. Obviosuly it has one of the Himalayans, S. andersonii perhaps, in its parentage. These do well in my climate. It was wintered outside in an open plunge.
Primula x meridionalis is the binomial for the hybrid between P. allionii and P. marginata that Robert Rolfe persuaded me to formalise some years ago now. As far as is known all the hybrids are sterile, so that individual clones should be identified after the binomial, as in, P.x meridionalis 'Miniera'. This (pictured below) is by far the best known of these crosses, discovered in the wild by a past Editor of the AGS Bulletin and Headmaster to the Elliott boys (Roy was to succeed him as editor) C.C. Mountfort. The name P. x meridionalis covers all of these hybrids (there are only a few; another one, 'Sunrise' will flower shortly for me). Most if not all of the other hybrids were raised in cultivation. I believe several newish examples have been raised in the Czech Republic.
A lovely example was shown at the Cleveland Show last weekend by Peter Hood which appeared much dwarfer and with less crinkled flowers than is usual. Peter said that he had deliberately potted it 'down'. This technique appeared to have bee successful in presenting the plant 'in character' and might work with other European primulas too.
I should hasten to add that the plant shown is my scruffy individual, not Peter's pristine example!
There has been a flurry of correspondence recently amongst those interested, particularly in Scotland, resulting from the introduction by the Dane Jens Nielsen of seed purporting to be of Primula odontocalyx. Suffice it to say that I appear to have been sent pictures of two quite different looking plants. One with blue flowers with a white centre and notched petals might or might not be P. odontocalyx. I believe others of the same gathering are not this, but with pink entire petals are the same as the plant I grow from a Rix gathering from the Erling Shan in 2002 as Primula moupinensis ssp. barkamensis. I repossessed this slightly charmless plant last year through the generousity of David and Stella Rankin and it is coming into flower now. Unlike its highly stoloniferous relative, ssp. moupinensis, it lacks stolons and is later flowering.
Last week, Sheila and I went in horrifically freezing conditions to nearby Bywell Chruchyard to see if much remained of the famous displays of Eranthis and snowdrops there. The aconites were completely over, and the snowdrops were starting to wither. I was unable to locate a few yellow ones I had seen there in past years. However, I was delighted to discover a considerable patch of Galanthus elwesii which I had not soptted there before. Interestingly, some were 'normally' marked (for that species), but others had only a single terminal mark on the inners and so could be classified as 'var. monostictus' (the old G. 'caucasicus;' of gardens).
By the way, G. elwesii is only just coming into flower in my garden! In April!