Kent Alpine Gardener's Diary
This entry: 19 February 2016 by Tim Ingram
Making and Planting Troughs.
Making and Planting Troughs - based on the meeting of the East Kent AGS, 12th February 2016
'One great advantage alpine gardeners had in the 1930's was access to plentiful stone troughs. R.C.C. Clay in his account of 'Trough Gardening' (Bulletin of the Alpine Garden Society Vol 7, p.16, 1939) obtained "upwards of 50 of my troughs [as] thanks offerings from patients...". Nowadays you would have to be an exceptional doctor to achieve such largesse! He advises to "Always plant for effect and not for natural association. The most beautiful plants do not grow together in nature any more than do the most beautiful women. Make a picture: do not illustrate a textbook".'
Growing alpines in troughs has a long and valued history, especially in smaller gardens and to give much more control over soil and growing conditions for plants. There can be great skill and artistry in growing alpines in this way - which I will show later - but the first step is getting your trough. True stone sinks, like this one in France, are prohibitively expensive for most gardeners, and exceptionally heavy and difficult or impossible to move once placed.
Old glazed sinks, like those I show below given to us by friends and which we intend to work on through this spring, are more manoeverable but still require coating with mortar to look anywhere near natural.
This process is well described in the online leaflet on this website - see:
... and this is illustrated in the following photographs. These sinks are of good depth and size for growing a wide variety of plants and reasonably moved when empty using a strong sack barrow.
The idea of using fishboxes and simply painting them to resemble stone at first sounds far-fetched. But in our talk this February Jeremy Spon convinced us how truly effective this can be with care taken to mimic natural stone. The cost is negligible, useful in a time of recession, as well as making use of boxes otherwise thrown away into landfill, and the results surprisingly strong and reliable over as many years as solid troughs - as well as being relatively lightweight and easily moved. The disadvantage is that fishboxes are often shallow but this can easily be overcome by the use of stone as I will show later. Ideally thicker walled boxes will have greater strength and most resemble natural troughs and look best in the garden. These are the examples that Jeremy showed us at the meeting and which I will describe in a little more detail.
Though light these polystyrene boxes have a structural integrity which allows them to hold a similar weight of compost and stone as more traditional troughs - though clearly they are vulnerable if knocked or moved without care in providing good support.
Jeremy's demonstration was based on the description given by Ian Young on the website of the Scottish Rock Garden Club in which the polystyrene is scraped and cut to roughen the surface, sealed with a heat-gun (used for paint stripping) and, critically, painted with masonry paints to give the appearance of stone. See:
This last step takes care and imagination and Jeremy's demonstration was very convincing, the end result as visually convincing as coating troughs in mortar. Here for comparison are close-up pictures of fishbox, hypertufa-coated and natural granite troughs. When planted up and viewed from a normal distance all give an acceptable impression and grow plants equally well.
Roughening the surface of fishboxes is easily done and the resulting surface is 'sealed' by careful use of the heat-gun. The trick in obtaining a good impression of stone is using several different colours of masonry paint to give a varied finish - ideally beginning with darker and reddish shades and then superimposing a more natural stone colour on top of these, applying the paint by stippling in the way shown by these two pictures.
In the hands of a craftsman and true expert plantsman the results can be thoroughly artistic and effective in growing very choice alpines, as this picture of fishboxes used by Jan Tholhuijsen shows. Here stone has been used to give height and planting crevices and the troughs easily given overhead protection when necessary, important for many cushion forming species and plants normally protected under snow in winter. (My thanks to Jan for permission to use this illustration).
The purist might baulk at using fishboxes in this way and always choose natural stone, but the purist will also have greater resources. The next step - which Jan's picture illustrates well - is planting the troughs, where the true artistry of growing alpines comes in and where it is possible to gain great inspiration from the work of others. The difference between growing individual plants in pots and miniature collections in troughs is significant because, though in both cases the aim is to provide ideal growing conditions for particular plants, a trough resembles much more closely the garden situation where plants are grown in combination and given a setting. This is obvious to state but much harder to achieve successfully in practice. I was challenged by a new member of our Group and of the AGS, Sarah Morgan (who has worked with plants commercially, run lecture courses at horticultural colleges, and has her own Garden and Landscape Design practice) to convince her how effective troughs can be in the garden setting. This is a challenge to be taken seriously and so for the remainder of this entry I will illustrate a range of examples especially taken from gardens in the Czech Republic but also in the UK and Ireland, and leave the reader to come to their own conclusions.
Troughs are a fine way of growing many plants otherwise difficult to grow in the open garden but perhaps more importantly again can contribute significantly to the overall impression of the garden. Here are two true stone troughs in Capt. Peter Erskine's garden, associated with what must be one of the finest rock gardens in the country. But imagine the scene without the troughs? They make a connection between the house and surrounding more formal area and the natural impact of the rock garden itself. These are simply planted with not too many plants but including fascinating species such as Physoplexis comosa, which prospers especially in tufa.
More typical perhaps is this small garden made by Rosemary and Paul Powis (which I have been helping Paul with in recent years). The troughs in the foreground are open and sunny with androsaces and silver saxifrages amongst other plants, and in the background between a specimen of Cornus kousa and a magnolia - more shaded - is one planted with dwarf rhododendrons, primulas and Saxifraga fortunei. They add interest to the scene just as before and accentuate the importance of microclimate in planting, which is the essence of any plantsman's garden and sensitivity to the cultural needs of plants.
Troughs themselves can also be placed together in an extremely artistic and harmonious way, reminiscent of Eastern gardens, as here in JiřÍ Balatka's garden. This is so effective as a scene because of the remarkable variety of dwarf conifers, notably pines, but nicely interplanted with alpines and sempervivums amongst rocks. Again every part of the picture contributes to the whole and has been carefully considered.
And here is the simplest of troughs planted with just Primula auricula and Saxifraga longifolia in Martin Brejník's garden (which I have described in more detail in a previous Diary entry in January 2014: http://www.alpinegardensociety.net/diaries/Kent/+January+/644/).
In many of the Czech gardens stone is as dominant and important a feature of troughs as the plants themselves, which is certainly something to learn from in the UK. The benefits are manifold, notably in providing planting crevices and a natural setting for what are after all 'rock plants', but significantly in ameliorating fluctuations in moisture levels and temperature which can often make growing alpines so challenging. Crevices between stones create a deep and narrow root run which improves aeration and drainage (as also found in deep pots) and are valuable for giving height in shallow troughs. The stones themselves warm and cool slowly and insulate in the same way as the trough does itself. These two pictures in Miroslav Stanek's garden illustrate this - the first quite crude and simple with different forms of the spring gentian, and the second, perhaps more contained, with dwarf daphnes and androsaces.
At the 2nd International Rock Garden Conference in the Czech Republic in May 2013 one of the most stimulating demonstrations was this one by Vojtěch Holubec showing how to use thin stones to create planting crevices. I took the second picture after he had made this - in not much more than 15 or 20 minutes - as everyone pointed out how to improve on it 😉. The point really is actually how effective this way of using stone is, and how individual is the end result. Troughs provide an artistic expression in growing plants just as Jan's picture earlier on shows.
The scope is wide and can be very simple as with these two troughs containing just sempervivums.
Tucked in close to the house with protection there is scope to grow quite tender plants successfully such as these echeverias in Elizabeth Cairns garden...
The Woking AGS Group has used these two fishbox troughs to illustrate contrasting plantings in their displays put on at the Hillside Centre, RHS Wisley...
One very effectively shows saxifrages growing in crevices between thin slivers of rock - the second picture illustrates the same type of planting in one of the stone troughs next to the alpine houses at Wisley.
The second shows a very different planting with shade loving species, suitable for a much cooler spot in the garden, and these woodland plants have immense appeal and gain from being observed closely.
This simple circular concrete trough in Rosemary and Paul Powis' garden has had Jeffersonia diphylla growing with Hepatica nobilis and an erythronium for a decade or more with minimal attention. The possibilities for growing choice woodland perennials, ferns, dwarf rhododendrons and ericaceous plants, and very much more are endless.
I will finish with these three examples of circular concrete troughs in Kevin Begley's garden near to Limerick in Ireland which perhaps more than any others show the versatility and skill of gardening with troughs. These are large containers, which gives greater scope in making striking pictures, and drama is given by height and scale. The display of lewisias is as stunning as any I've seen. The final trough shows that even on this relatively smallest of scales there can be markedly different exposures to light and shade and that planting a trough can have the same sort of subtlety as planting within the garden itself. (My thanks to Kevin for permission to show these pictures).
Much more information and numerous examples can be found on this valuable thread on the Scottish Rock Garden Club Forum: http://www.srgc.net/forum/index.php?topic=3537.0 and in this book by Duncan Lowe published by the Alpine Garden Society. Undoubtedly trough gardens need experiment and experience to succeed as well as many of the examples I have shown, but the results justify the time and effort put in and bring something unique and fascinating to the garden, as well as enriching an understanding of the plants grown.
(for planting details of the troughs made by Jan Tholhuijsen earlier in this entry, see the 'International Rock Gardener - August 2015': http://www.srgc.org.uk/.../2015Aug261440625534IRG_68.pdf)