A Northumberland Alpine Gardener's Diary
This entry: 30 September 2012 by John Richards
Northumberland Diary. Entry 225.
Alpine troughs are just containers, and plants in garden containers run short of nutrients in quite a short time. Recently I have been buying a general purpose compost sold by Westland called 'West + light and easy'. I like this, not particularly because it is light and easy, but because in my view it has good physical properties, being open and full of air-spaces. It seems to be composed chiefly of pulverised bark and composted coir, and although it is a little hydrophobic (doubtless due to the coir), at least it does not get soggy and waterlogged, a great boon in the current climate! But, this compost specifically states that it contains nutrients for four months; just enough for a season of bedding or hanging baskets I suppose.
Indeed, we do change the compost in our (non-alpine) containers at least once a year (or at least the upper half of the compost if we are feeling stingy). However, when it comes to the alpine containers, troughs, fishboxes and the like, I doubt if the compost gets changed once every four to five years.
In the 'good old days', I dare say that troughs were filled with a mixture of well-sieved garden compost, leaf-mould, loam from stacked turves as well as grit and sand, so that they released nutrient slowly from clay-bound particles and retained their 'goodness' for many seasons. I do make garden compost (full of weed seeds!), and leaf-mould (which I do incorporate into trough composts), but the loam here is far too greasy to be used in troughs. Instead I use commercial bagged composts, which doubtless run out of nutrient as quickly as they say they do (within a growing season).
Bearing in mind the success of alpines grown in sand-beds, or screes, apparently devoid of any discernible sustenance, one might ask what the problem is? However, there is no doubt that alpine composts in containers become stale, compacted, moss-bound and inimical to any plant growth with a couple of seasons. They need replenishment at depressingly (and expensively) frequent intervals.
I find that the autumn is a good time to replenish troughs and fishboxes, not least because there are a good number of this year's seedlings and propagated cuttings to find homes for. I have had a quite successful season (so far!) with seedling primulas, meconopsis and the like, and the more vigorous were either planted out two to three months ago, or moved to pots in which they will spend the winter under cover. However, there are spares, many of which are too small to sell, and it is my depressing experience that if these are not found a home now, they do not survive the winter in their tiny pots.
I must say that many of my primula fishboxes were in a sorry state. Many had been ravaged not only by the stale compacted soil, but by virus, so that I grow far fewer healthy petiolarid primulas than for many years. I have had a near-total clean-out, disposing of many sickly plants, and emptying the compost completely, to replace-plant with young healthy seedlings.
In this case the replacement compost is composed of one part West+ light and easy to one part equal measures of granite grit, sieved leaf-mould, and perlite. After the plants have been positioned, the whole is top-dressed with granite grit and given a thorough water.
In the above example are two plants of P. pulchella (bottom right), two of P. maximowiczii centre (very small; those in the garden or in large pots are huge, but these have been starved), one of P. apoclita (top centre), one P. flaccida, and a dwarf Corydalis flexuosa. Below is a group of troughs, all recently replanted in which Primula matthioli alba (Cortusa to you!), figures prominently.
Alpine (as against 'primula') troughs are kept on the terrace on the other side of the house where they receive more light. In these cases, the replacement compost is composed of West+ Light and Easy together with more grit, less perlite, and no leaf-mould. The compost is about half the bulk. In this case, many subjects had survived from the troughs before replanting, and once they had been divided, thoroughly cleaned of moss and weeds (pearlwort and the New Zealand Bitter-Cress are particular bugbears here), some were replanted. This rejuvenation is greatly appreciated by Porophyllum saxifrages, which often grow vigorously from tiny, even unrooted, scraps.
Formerly I had attempted 'crevices' in several of these containers, using vertically placed shards of the local shale. As previously reported, for whatever reason many alpines appear not to enjoy being planted in close proximity to this shale, and I have discontinued its use. The result is less 'artistic', but I hope that the plants will respond, to form their own eye-pleasing combinations.
As will be seen, I have incorporated several recent purchases into this fishbox. The £3 tags remind me somewhat of the '7/6d' in the Mad Hatter's hat-band, but never mind!
The larger trough I made many years ago from Yorkstone slabs bracketed and bolted internally has also been replanted. I find this container has been a martyr to ant nests, perhaps because they can get in at the joins, and subsequently to violets, as the ants bring the seeds with their sticky elaiosome into the nests. Viola riviniana is a real problem in this trough area. Doubtless the cure is to watch for infestations and use ant powder as soon as the insects appear.
As I have often noted before, Sheila and I volunteer every Friday at the University of Newcastle Botanic Garden, Moorbank, in the centre of Newcastle, where we join a team of perhaps 10-12 like-minded folk. This is great fun, and organising the garden, and its openings for NGS and other organisations takes a good deal of our time. Usually, we are so busy that I forget to take photos, even if I have remembered to take the camera. However, by last Friday the weed problems were starting to subside for the year, and having organised parties of bulb planters, I was able to wander around with a camera for a few minutes.
Naturally, colchicums and cyclamens are prominent at the moment. In this photo, colchicums struggle through a melee of a viticella clematis, and Hypericum androsaeum.
This is a good time of year for the heather bed.
The penstemon here (many are only just starting to flower now) combines well with the purple Cotinus coggygria.
As seen above, the hydrangeas have not flowered well this soggy summer, but there is still some colour in that bed.
The pond area tends to be a riotous jungle, but the waterlilies are flowering well, despite having been out of the water for 12 months last year while the pond was remade.
This 'silver bed' was Sheila's idea, and is very effective with Helichrysum splendidum, Santolina, Artemisia 'Powis Castle', and a variegated Euphorbia characias.
Herb beds are not always colourful, but we have worked hard to ensure that the interest peaks in late summer.
Finally, one area is kept clear of permanent plantings in case it is needed for experimental purposes. In late spring we broadsow cornfield weeds and here cornflowers and cornockles make a brave show. When the frosts come, we let them self-seed and rake in the debris after the stalks have been taken to help with next year's display.
Back home, it has proved a much nicer day than the forecast (for a change!) and I was suddenly struck by how forward much of the colour is. This caused me to grab the camera and take photos from out of four different house windows. Its nice when the sun shines! First, here is Sorbus fruticosa against the Betula jacquemontiiit from the kitchen (north). The blackbirds have already taken most of the berries.
Second, Parrotia persica from the living room (north again).
Third, Acer crataegifolium from the kitchen (south).
Four, Hesperantha coccinea from the conservatory.
Autumn, I love it!!