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Kent Alpine Gardener's Diary

This entry: 17 August 2017 by Tim Ingram

The evolution of a trough.

The evolution of a trough

Even the smallest landscapes in a garden evolve. Because of the way we view plants and gardens in the 'moment' and with the partial view of the camera (and with the tendency of the artistic eye to 'judge'), the more subtle changes as plantings adapt over time to climate and place are less observed. And yet these are the true features of plants and how they become established (or not) in an environment that continuously varies. Growing alpine plants in the garden accentuates this way of viewing plants in general because alpines are often so finely tuned to extreme habitats, and the trough - a miniature landscape in itself - acts as a good example to learn from. These pictures illustrate just one trough over a period of four years (initially inspired by visiting the 2nd International Rock Garden Conference in the Czech Republic in May 2013 and the beginnings of replanting a second one that has not been so successful over time. Like many plantings in the garden itself time modifies original expectations, but observing closely hopefully has the consequence of greater success in future plantings.



John Good and David Millward, in their really valuable book 'Alpine Plants - Ecology for Gardeners', bring this into scientific focus, and more than anything else a garden does enable plants to be observed closely over long periods. That same sense of ecology that comes from studying plants in the Natural World can become more and more evident in the garden too as it matures. As a corollary to this, successful plantings tend to be those that become self-sustaining, and though many alpines do come from extreme environments it is surprising how they can adapt to the lowland garden.

Alpine troughs can be the best examples of all because of how easily they can be sited in specific places with different light and exposure and with soils varied for different plants. Up to now we have grown most alpines in raised beds and in the garden itself, but would like to concentrate more on troughs for choicer and less common species. There is a lot of artistry in growing plants in this way as I have referred to before, and notably in these three examples from Jan Tholhuijsen (as a supplement to his e-Book that I mentioned just recently), Kevin Begley at Coolwater Garden in Ireland, and Ian Young in his and Margaret's garden in Scotland This is a way in which those two cultures of science and Art can become conjoined. There is a little way for us to go to be as successful with troughs as these three but the enthusiasm to try is there.

One of the best displays that I remember the AGS ever making at Chelsea was based around troughs, loaned from Ness Botanic Garden. This is nicely described by Robert Rolfe in the Quarterly Bulletin, Vol. 66, Decmber 1998, from which this photo is taken (and it's interesting to compare this picture with the one I showed in an earlier Diary entry, taken at an RHS Show nearly a century earlier).

It can be pretty difficult in the climatic (and sometimes personal) vageries of a garden to make plantings quite so eye-catching and full of interest, but troughs of all things lend themselves to this sort of detailed form of gardening. Duncan Lowe in his book, 'Growing Alpines in Raised Beds, Troughs and Tufa', describes this so well, and illustrates examples with his inimitable pen and ink drawings. To complete reference to growers on other continents and in other Rock Garden societies, here is a useful link to the Forum of the North American Rock Garden Society, which in turn gives further references, particularly to gardening with tufa Duncan Lowe's simple drawing below shows that way of using plenty of stone to make a series of crevices and to landscape a trough.

So back to my more mundane examples. This trough is a relatively shallow one, and to give it greater height we have used irregular pieces of Kentish ragstone, arranged diagonally to make planting crevices.

In summer 2013, when this was planted with a mix of choice species brought back from the Czech Alpine Conference, I had high hopes that these would establish in the sandy/gritty compost. Here are plants such as the beautiful silver Veronica bombycina, a Callianthemum and Asperula, and Acantholimon venustum

And by the autumn and winter most still looked OK and were protected by a glass Dutch light cover.

By the following May of 2014, however, many had not persisted and the error of starting with such large established plants grown in rather different nursery compost than the medium of the trough was apparent. One that had grown away well though was the Turkish Salvia caespitosa (top right of this photo), just beginning to flower.

This plant is winter deciduous - seen in the foreground in the trough pictured here in February 2015 when we opened the garden for snowdrops. The trough was not covered in that and the following winter, and so plants have had to adapt to our climate year-round.

By June 2015 both the Salvia and Globularia incanescens flowered well and the tiny Corsican mint, Mentha requienii, had seeded in from the surrounding paving and colonised the trough rather too effectively!

On the reverse side sempervivums began to fill in, but curiously have since declined after flowering without really establishing new rosettes. The tiny Turkish Hypericum imbricatum and Olympiosciadum caespitosum and Globularia pictured here are still going strong two years on.

Now in August 2017 the planting has changed almost completely from its beginnings in 2013, but those plants present have grown steadily and begun to make a more stable miniature landscape. I wouldn't describe it as an unqualified success, but it melds well with other troughs and plants on our patio and gives interest throughout the year.

Fellow gardeners are often very generous and the trough alongside it has been replanted with a large piece of tufa we were given recently, after a much less effective previous planting. This has given the chance to try growing more choice species of alpines planted into holes drilled into the tufa, and so if I am still writing this Diary in four years time you will get to see the results! Tufa is such a remarkable and ideal material in which to grow alpines and so I have high hopes that many of these will establish.

These are several examples: the wonderful silvery-leaved form of Edraianthus pumilio...

Eriogonum caespitosum - rescued from the earlier planting. Both of these have full exposure to the sun...

And Saxifraga x borisii 'Mona Lisa', planted into a hole on the shadier side of the tufa. Several other saxifrages await a similar suitable cooler aspect and this block of tufa is big enough that it may end up planted with twenty or so different alpines.

For now the tufa looks sparse and lacking and there is more hope than experience; time will tell. In the trough below the tufa grow Saxifraga oppositifolia, S. callosa subsp. catalaunica (with its very marked silver-encrusted foliage) and Potentilla nitida. As with all plantings in the garden we keep records as drawings and photographs, and these Diary entries supplement those as well and hopefully give interest to readers. There are plenty more plants awaiting homes in new troughs and I look forward to describing these as time goes on. 

It may be hard to convey the 'fun' that there is in gardening with alpines in this way (to borrow the word used by Frank Kingdon-Ward in one of his books) unless you already have experience of these plants, but fun it undoubtedly is, as well as a great deal more.

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