Alpines in Troughs and Sinks

Genuine stone troughs at the RBG Edinburgh, with attractive under-plantings where the slabs have been removed around the troughs and the plants appear to have spilt over and taken up residency there.  One of the most rewarding and fascinating ways of growing some of the smaller, more delicate and difficult of alpine plants is in troughs and sinks. I would go so far to say that one doesn’t even need a garden, (in the broadest sense) in order to grow and enjoy alpine plants. Even the smallest of proverbial pocket-handkerchief plots can accommodate at least one alpine trough, be it patio, courtyard or garden. Many splendid examples of trough collections can be seen at the RHS Garden Wisley, the RBG Edinburgh and at the AGS Centre at Pershore. Many AGS Members Gardens are open during the spring and summer and this too is where you will see many superb examples of alpine trough culture. Over the past 32 years I have made 15 hypertufa troughs for use in my garden and almost the same amount for relatives and friends. Most of these have been glazed enamel sinks coated with hypertufa, whilst others have been made from a mould using two boxes, one inside the other. In the mid 1980’s I made a number of these moulded troughs, (510mm x 300mm x 205mm) planted up with alpines, for a local garden centre, on a sale or return agreement. The demand far exceeded the rate I could supply them.
What I propose to do in this section, is describe the choices one has in acquiring troughs and sinks, buying the genuine article, buying a reproduction or various ways of making them yourself.
Buying troughs and sinks
Genuine stone troughs at the Royal Botanic Gardens Edinburgh. Genuine stone troughs at the Royal Botanic Gardens Edinburgh.

Unfortunately, genuine stone troughs and sinks are increasingly difficult and expensive to come by. The stone sinks in the kitchens and sculleries of Victorian houses and farms were replaced long ago by the more hygienic glazed ones, while the larger drinking troughs used by cattle and horses have given way to galvanised iron tanks. The occasional stone trough or sink sometime turns up at country auctions, but dealers know their value and scarcity, and an astronomical price will probably be asked for them. There have recently been a few advertisements in ‘The Alpine Gardener’ offering genuine stone troughs and sinks for sale, and a search on the internet will come up with a number of positive results. So even though they are scarce, it is still possible, with a little diligent searching, to acquire the real thing. The prices can range from a few hundred pounds for a small shallow sink, to well over a thousand pounds for a larger, deeper horse trough.

The first three pictures shown on this page, (above) are of genuine stone troughs at the Royal Botanic Gardens Edinburgh, photographed in 1986, showing how appealing a group of troughs can be on a paved area, where some of the paving has been removed to allow for the planting of dwarf shrubs and alpines. The same pleasing results can be achieved by using reproduction or self-made troughs which will cost considerably less that the genuine article.

These ‘®Elmdene’ Lightweight Rectangular Stone Troughs are made from a lightweight polymer resin material blended with crushed stone.
A number of garden centres and nurseries now have a diverse assortment of shapes, sizes and textures of replica troughs and sinks; and these won't deplete your bank balance as would buying the real thing! These are made from reconstructed and compressed limestone, whilst others are made from a lightweight polymer resin material, with an authentic and attractive stone-like appearance, which are available in a Sandstone, Yorkstone and Cotswold finish and are further enhanced by an antique weathered look. I have seen a number of these lightweight resin troughs planted up with alpines and I must confess that they do make an attractive feature on a paved or gravelled patio.
Whilst the purist might throw his arms in the air at the thought of planting alpines in a plastic reproduction trough, one must bare in mind that not everyone has the desire or ability to make their own. They are a fraction of the weight and cost of an original stone trough, which means they can be moved within the garden and need not be left behind if you move house. Fashions and necessity change with the times and I think that if the plants are happy, the grower is happy and the whole set-up is pleasing to the eye then one cant ask for more. It is all a matter of personal choice. Having said that, I feel that alpine plants grown in some of the more ornate plant containers seen in many garden centres, (those embellished with festoons of acanthus leaves, ribbon-tied roses and basket-weave decorations) look completely out of place. These types of container are more suited to the planting of pelargoniums, begonias and the like, in a more formal setting.
Making your own troughs and sinks

Click on picture to enlarge.By far the cheapest way to build up an alpine trough collection is of course to make your own. There have been many excellent articles on various methods that have appeared in past bulletins and they all require the use of hypertufa. So what is hypertufa? It may be appropriate at this point to first explain what tufa is. Tufa is a pumice-like rock, formed by water containing carbon dioxide seeping from limestone formations. It eventually becomes pitted with bubble-like holes, much like “Aero” chocolate or a sponge. These holes are left when the vegetable mater, around which the rock forms, eventually decays. It is a wonderful medium in which to grow alpine plants. Hypertufa is a man made substitute, which I believe was first introduced and suggested in the AGS Bulletin in the mid 1930s by F. H. Fisher who was advocating its use in the making of rocks rather than using it in the creation of troughs. No one knows who made the first hupertufa trough, but I have always used the recipe suggested by S. E. Lilley.

This is as follows:
vSand – 5 parts.
vCement – 2 parts.
vPeat – 3 parts.
The sand. Should be a course gritty concreting sand and I usually put it through a fine 6mm sieve to remove some of the larger grit and pebbles.
The cement. This should be a fine grade Portland cement, you can now buy it by the half-bag, as a full size bag will usually be far too much if you only plan to make a few sinks at a time. Don’t be tempted to use old cement that has become a bit lumpy, it should a fine powder throughout.
The peat. The black dampened sedge peat is not recommended. I have always used a fine Irish sphagnum moss peat. This comes in a compressed bale, which is bone dry and has to be broken up. I pass this through the same 6mm sieve. There are of course, alternatives to using peat. Coir (coconut fibres) or a fine grade composted forest bark could be used. Again, both of these need to be passed through the sieve.
All three ingredients are thoroughly mixed dry, and then water is added, a little at a time, making sure that you don’t end up with a mix that is to sloppy. I use a cement colourant that can be either in powder or liquid form. Both are available in a number of colours. I use a dark chocolate brown to achieve a sandstone finish to the troughs. The powder should be added to the dry hypertufa mix, before the water is added. The liquid should be added to the water then mixed with the hypertufa mix. To achieve a darker or lighter finish is dependent on the amount of colorant added.
Covering a glazed sink.

The white enamel glazed sink, (sometimes referred to as a Belfast sink), which has been replaced by more modern stainless steel and ceramic sinks, are themselves now becoming scarcer. In the 1970s and early 80s these were relatively easy to get. I would ask friends and relatives who were, or had connections with builders and plumbers to keep a look-out when they knew of any older property being renovated or demolished. I soon had more offers of sinks than I could cope with; I would do three at a time, and soon my small patio finished up with 15 hypertufa troughs. Although they are not as easy to come by today you can still see them full of weeds in the front garden on some housing estates. There are still some older terraced houses being knocked down that may have a white enamel glazed sink in the kitchen. Ask the builder to let you know if he comes across one, knock on the door of the house and ask if you may purchase the sink in the front garden that is full of weeds.

OK!…So let us assume that you now have your first glazed sink and are about to cover it with hypertufa! The first thing to do is to thoroughly clean it of any greasy dirt and grime, use a scourer or sharp sand with the cleansing agent to cut through the stubborn grime. Allow to dry and then apply a bonding adhesive to the glaze. Polybond, Unibond and Marleybond are just three of the many PVA bonding adhesives that are available from DIY stores and builders merchants.
Allow the adhesive to become slightly tacky before applying the damp (not wet!) hypertufa mix, this should be of a consistency that wont fall off when applied to the sides of the trough. If the mix is to wet, gravity will pull the excess water in the mix towards the ground taking much of the mix with it. This wont perhaps be noticeable straight away, but if you return a few hours later and find mostClick to see a larger image. of the mix has slithered off, the mix is to wet. Remember to apply the mix over and down the inside edge about 6 centimetres and also a little under the outside base so that no white glaze can be seen when the sink, (or should we now start to call it a trough?) is completed and filled with compost and plants.
Once the covering of hypertufa has dried out a little and before it begins to harden it can be made to look like a realistic stone trough by using a piece of shaped wood, an old metal chisel or something similar to create a finish much like genuine article. Get your inspiration from a real stone trough or from photographs. Finally, finish of by giving the whole surface a good ‘going over’ with a soft brush, this will achieve a weathered look by rounding off any sharp edges and corners. To give it an aged appearance and encourage lichen, moss and algae, spray or paint on a liquid fertiliser or milk. After a couple of seasons your hypertufa trough will be difficult to distinguish from the real thing.

Covering a polystyrene box.

The polystyrene inner packing that comes with many electrical appliances, such as a microwave oven, TV, fridge or cooker can be used; but I think the ideal packing to use, if you can get, is that which supermarkets and fishmongers have fish delivered in, as they need little or no altering before use. With other types of packing you may have to cut pieces off or glue pieces on to get the shape and size you want.
Covering the polystyrene is done as described when covering a glazed sink, using the same hypertufa mix and a bonding adhesive. The most obvious advantage of these is that they are much lighter, and therefor easier to move that the other mentioned troughs. I have used such a trough for growing the frost tender Rhodohypoxis, which is easily moved into the garage during the winter and bought out again in the spring

Shown far left are Polystyrene fish box covered with hypertufa. two nice size troughs made by covering polystyrene boxes in which frozen fish is delivered. Near left is the sort of polystyrene box you should look out for! Remember that the greatestPolystyrene fish box - with fish. weakness when filled with compost and plants will be the base of the trough. Place the two bricks on which the trough will sit about ¼ of the length in from each end, and if you do need to move it at any time it is advisable to use a couple of wide strips of wood and get someone to help. Whatever type of trough you buy or make should last a lifetime, and can often be passed on to the next generation of gardeners.

Making troughs in a mould.
This is a very cheap and easy way of making a collection of various sizes of troughs. So what do we use as a mould? Simply two boxes, one inside the other. These can be of cardboard or wood. Cardboard boxes can be got from nearly all supermarkets and to make one trough you will need two boxes, a smaller one inside a larger one, with enough of a gap between them to pour and compact the hypertufa mix. An important point worth mentioning is the viscosity of the hypertufa mix; it should not be able to be poured easily like a Victoria sponge mix, but more like a rich and heavy fruit cake needing the assistance of a spatula to help it from the container.
The four pictures below show how a wooden mould is used.
Figure 1 shows the four plywood sides of the outer box; plus the eight tapered dowels.
Figure 2 shows the assembled outer box.
Figure 3 shows the four inner plywood pieces in place; make sure they are slightly tapered towards
the bottom to make it easier to remove them when the hypertufa is set. Note also the board to keep
the mix from staining the paving slabs and the soil used to keep the inner pieces in place.
Figure 4 shows the finished trough several weeks later. It was sprayed with liquid manure to
encourage the green algae to form; giving the trough an aged weathered appearance.

You will need to find an area where you can position the larger box and have easy access to all four sides. Also take into account the fact that it will take some time to set and should therefor be away from where children - and adults for that matter – could accidentally disturb the setting mould. You will also need a number of bricks or stones, anything heavy to be placed around the outside of the larger cardboard box to prevent the sides bulging out to much when the hypertufa mix is poured in. Some form of reinforcement such as wire mesh, chicken wire, old wire coat-hangers or any suitable scrap metal strips should be used to give added strength to the finished trough. Once your larger (outer) box is set up and your metal reinforcement is to hand you can start preparing your hypertufa mix as explained when making for the glazed sink. The mixture can be a little wetter for moulds as the cardboard will absorb some of the water and you want to avoid air-pockets forming between the two boxes.
The first stage is to start with the base of the trough by pouring the hypertufa mix on the base of the larger box to a depth of about 2 centimetres – like pouring a cake mix into a cake tin – making sure that the edges and corners have been filled. Next lay a few lengths of chicken wire or mesh on top of the mix with the ends of the chicken wire or mesh bent up at right angles about 8 centimetres where the centre of the upright sides will be. Pour another 2 centimetres over the base so that you end up with a base of around 4 centimetres thick with the metal reinforcement sandwiched between. Make two drainage holes in the base - about 4 centimetres in diameter – using a piece of wood, like a pencil or something similar, swirling it round between the metal reinforcement if need be.
You can then place the smaller inner box on top of the 4 centimetres thick hypertufa base, making the gap between both boxes as equal as you can. The gap should be no less than 4 centimetres for a small trough and more if the trough is larger and heavier. Place a few bricks in the inner cardboard box to prevent it from moving when you pour the hypertufa mix between the cavity of the two boxes. Alternatively you can fill the inner box with garden soil, sand or gravel.
The hypertufa mix can now be poured/scraped into the cavity between the boxes. I think it is better to go all around each of the four sides a little at a time rather than try to fill one side completely before starting the opposite side. Fill all four sides to a depth of about several centimetres at a time, tamping and compacting the mix with a piece of wood that will go between the box and metal reinforcement. As you build up and compact each layer remember to incorporate more metal reinforcement, with some bent at right angles to strengthen the corners. When you have filled each of the sides to the top, cover the whole finished trough with polythene sacks to allow it to not dry out to quickly. Leave it for about two days and then remove a little of the outer cardboard box which will come away quite easily. If it appears that the mix hasn’t set hard enough leave it for another day or two.
Once the trough has set hard enough, the whole of the outer box can be removed. The corners and edges should be rounded off and the whole outer surface of the trough should be given the same finish as described for the glazed hypertufa trough earlier. Turn it on its side and finish of the drainage holes if necessary.
Your trough is now ready for planting and a little thought should now go into where it will be permanently placed.
THE SIGHTING OF THE TROUGH OR SINK

The first thing to consider is where to position your trough; this of course should be done before being filled with compost and plants, as once it is filled with compost and planted up it will become quite a heavy item and won’t be so easy to move, especially if large. The majority of alpine plants do best in an open sunny position away from overhanging tree branches where the drip from rain and melting snow may cause problems. The ideal place would be a south-facing paved or gravelled patio or courtyard. They can make a very attractive feature in such a setting, especially when three or four various shapes and sizes are grouped together. Placing them under the kitchen window or a bay window just a few centimeters away from the brickwork can bring an otherwise stark and bare wall to life when the plants come into flower. It is always advisable to raise your trough from the ground on a plinth. This has the advantage of bringing the plants up to a more convenient height for viewing and maintenance. It keeps the drainage hole clear and they just look better raised up. Walling stone, bricks, breezeblocks or tiles can be used. If you have a hypertufa trough - either cast or a covered glazed sink – you can cover the breezeblocks with hypertufa or even cast a number of plinths to match your sink! Matching plinths made of lightweight polymer resin and compressed limestone are available for the replica troughs and can be purchased from many garden centres nowadays.

DRAINAGE AND COMPOST

Our trough will need at least one drainage hole, with a diameter of not less than 3cm. Place a few pieces of broken clay flowerpot or perforated zinc over each drainage hole. Next, cover the bottom of the trough with about 3 cm of coarse drainage material: gravel, broken pots, stone chips or something similar. (If you have a very shallow trough you can perhaps dispense with the drainage material if you have open well-drained compost.) Over the coarse drainage material, place about 3 cm of coarse bark chips, coarse peat siftings or turf with the grass side down. This is to prevent too much of the finer compost being washed down towards the coarse drainage. The next job is to fill the trough to within 3 cm of the top with a suitable compost. What then is a suitable compost for troughs? I have usually gone for a fairly basic mixture as suggested by the late Joe Elliott, in his book - 'Alpines in Sinks and Troughs'.

All quantities are by bulk:
Three parts good quality loam.
Two parts moistened sphagnum peat.
One part coarse sand.

If you use unsterilised garden loam you may unwittingly introduce worms into your trough. A few bags of John Innes Potting Compost No 2 or 3 could be used instead. Nowadays, there are strong environmental arguments not to use peat and, whilst there are now a number of alternatives available to the gardener, such as bark, wood fibre, wood waste, cocoa shell, coconut fibre (coir), refuse derived humus, sewage sludge and recycled landfill, their availability depends on where you live. I now use a fine-grade of composted bark, available in 80 litre bags, but I have to travel quite a distance for it as none of my local garden centres stock it. Whatever you use as a peat alternative, the main criteria should always be that the product should be crumbly, not smelly and with no or few recognisable raw materials. As for sand, I use coarse concreting sand. Make sure that the sand is washed; any reputable builders merchant should be able to supply this. Mix all of your compost ingredients thoroughly, adding a 3-5 mm coarse grit if you want a more open, faster draining compost, or more peat if you intend to grow peat loving plants. When filling the trough with your compost mix, do a little at a time, firming down each 10 cm layer (not forgetting the sides and corners) at a time. Do this layer firming down until you are within 3 cm of the top — enough for a good topdressing of stone chippings, slate or gravel. However, do not put the topdressing on until the rocks have been positioned and the plants put in.

CHOICE OF ROCKS
Afew well-placed rocks not only give a pleasing finish to a trough; they also have a practical purpose. Many alpine plants benefit from Birds eye view of planted trough. having their roots in the cooler conditions under the rocks. Planting close to the north-facing side of a rock will partially shade from the hot summer sun those plants that do not like direct sunlight. Tufa is a wonderful material to use in troughs and a great many alpines will grow and flourish in this medium much better than in any other. It is very soft and porous and holes can be bored in which can be planted a large variety of saxatile plants. These will retain their natural characteristics and find a contentment that would be hard to beat. If you find that tufa is difficult to obtain, you can easily cast your own rocks of hypertufa at very little cost and effort. There are of course types of rock other than tufa that are suitable for troughs: sandstone, Westmorland stone, slate and indeed many other materials can be used in landscaping. Carefully selected tree-stumps could replace rocks to give the effect of plants growing amongst woodland ground litter; this would suit some ericaceous plants and small woodland bulbs. A recent trend gaining in popularity amongst a number of alpine growers is crevice gardening, and this is quite adaptable to troughs. This is done by placing slabs of rock on their ends and then planting the crevices Birds eye view of planted trough.created. John Page’s informative article in The Alpine Gardener (71:257) describes this in greater detail. Whatever type, shape and size of rock is used it is important that it is well bedded-in the compost with no air pockets beneath where ants or woodlice might set up a colony. Use a piece of wood or a trowel handle to firm the compost all around the under-surface so that there is no movement. It is much better to use two or three large rocks than several smaller ones. I believe that around 45% of the surface area of a trough can be taken up with rock. This may appear to be a lot, but once you have tried a few dummy runs by moving the rock around and viewing your creative achievement from all sides you will see how pleasing it looks. The largest rock will look better if it is placed off centre towards one corner of the trough and may take up to 30% or more of the surface area. The smaller rock(s) may take up about 15% or 20%. Try to visualise what plants you will be planting in the valley between the rocks, which plant will be suited to the north-facing side of that larger rock and which will look most effective tucked into that far corner to tumble over the side. I always derive immense pleasure and fulfilment from this stage, for I know that I am close to placing my first plant. So let us now move on to choosing the plants!
CHOICE OF PLANTS
Note:- Many of the plants mentioned in this section can be viewed in the 'Portraits of Alpine Plants' page, along with descriptive text.
There is an enormous choice of superb plants suitable for growing in troughs and sinks. Indeed, very many plants grow much better in these than anywhere else in the garden. The more vigorous and fastergrowing alpines should not be allowed a place, as these would soon smother the small, delicate and slower growing ones. The following is purely a personal choice of some of my all time favourites that have proved successful and given much pleasure over the years. For me, the most beautiful of all trough dwellers is the Spring Gentian, Gentiana verna, and its many forms. It has the most brilliant blue flowers of any plant. It is not long lived and should be perpetuated by young plants grown from seed; it is a lime-lover and does best in gritty, humus-rich soil. A complete contrast is the New Zealand G. saxosa, whose cup-shaped white flowers have grey-purple veining on the petals. This, too, is short-lived and should also be kept going from seed; on occasions it will self-sow. Do try Centaurium scilloides, which has tight tufts of small, rounded, shiny green leaves and bright rose-pink flowers. It will happily seed itself about and is not in the least invasive. Morisia monanthos represents a monotypic genus from Corsica and Sardinia, inhabiting coastal sands. The attractive, dark, glossy green, fern-like leaves are the perfect foil for the bright golden crucifer flowers that appear from March to July. Asperula arcadiensis is an exquisite species from Greece with pink tubular flowers that erupt from the delicate, woolly, grey foliage. This has been with me since I bought a plant in the early 1970s. I grow it in several troughs as well as in a raised bed.
The smaller-rosetted sempervivums are ideal trough plants. Long ago I planted a few rosettes of Sempervivum arachnoideum in a 3 cm hole in a piece of hypertufa. I snipped off any flower stalks that the plant attempted to put out and, in 25 years, it had formed a perfect iron-hard dome of just over 16 cm. Whilst the true species may be small in number the countless hybrids, forms and clones will give the alpine gardener a vast choice of distinct and worthy houseleeks. I feel that it is always best to go to a nursery and see them in the flesh, so to speak, as some catalogue descriptions do little to describe the beauty and variety of these plants. A few others of distinction are: S. nevadense (from the Sierra Nevada of Spain) with attractive apple-green rosettes, which are tinged red at the tips. S. calcareum ‘Greenii’ has jade-green rosettes, each leaf tipped a rich maroon, while the tiny S. minus bears a distinctive purple colour at the base of the leaves. The houseleeks not only revel in holes drilled in tufa but are equally at home when sandwiched in between rock crevices. Another genus that often thrives in holes and crevices is of course Saxifraga, in particular the Kabschia and Engleria kinds (two subsections of the section Porphyrion). The many forms of S. oppositifolia will usually put on a great show by completely covering their dark-green foliage with blooms from February to April. One of the finest is ‘Ruth Draper’ with large rich red flowers. S. x boydii ‘Aretiastrum’ has robust sulphur-yellow flowers, with a slight greenish tinge. Both S. wendleboi and S. burseriana ‘Gloria’ have lovely white flowers. S. x edithae ‘Bridget’ another very attractive plant, produces tight domes of silvery-blue rosettes and elegant arching heads of rosy-red flowers, each with a ring of yellow stamens in the centre. Do include some of the many cultivars of S. x megasaeflora in your choice, for they are indispensable to any trough. I have mentioned but a handful of the many saxifrages available from the specialist nurseries advertising in The Alpine Gardener. Choose campanulas with caution, as some are too rampant to be let loose in a trough, but there are a few notable exceptions. C. lasiocarpa from the Rocky Mountains and Japan is a gem worth trying. I have C. betulifolia growing in the corner of a large trough where it has been for many years but has never attempted to encroach on its neighbours. C. zoysii is a treasure from the eastern and south-eastern Alps and if you can protect it from slugs it is well worth trying it in a hole in tufa. Another outstanding plant for the same location is Physoplexis comosa. Planted several years ago in a trough it has never yet failed to produce its clusters of unusual bottle-shaped flowers. This too is a martyr to slugs and snails which, given the chance, would devour the whole plant in just one sitting!
Dianthus should be chosen with discretion, but some of the smaller ones, such as D. haematocalyx, D. freynii, D. alpinus and D. microlepis are excellent subjects.
Personally, I think that the majority of bulbs should not be planted in troughs with other alpines, with perhaps the exception of really diminutive ones like Narcissus rupicola, N. assoanus and N. rupicola subsp. watieri: none grow more than 15 cm high. The choicer Oxalis are fine, so too Rhodohypoxis. The vast majority of dwarf conifers offered in garden centres will become too big for a trough in as little as three years. If you want the really dwarfest, slowest growing conifers it is always better to seek them out from a nursery which specialises in these plants. They will often be smaller and more expensive than those offered by a garden centre. Because of their slow growth rate, it takes many years to produce a good-sized saleable specimen. Some writers state that no trough is complete without a dwarf conifer, but I do not believe this; of the fifteen that I have, only three have one. Having said this, the most popular one for a trough is Juniperus communis ‘Compressa’ which forms a dense, very slow-growing flame-shaped bushlet and will remain in character for many years. I have Picea ‘Tom Thumb’, which after 12 years has a diameter of about 16 cm, while Chamaecyparis obtusa ‘Mariesii’ has formed a dome of 12 cm in just over eight years. A small cutting of Chamaecyparis lawsoniana ‘Pygmaea Argentea’ was placed in the corner of one of the troughs but in eight years grew the size of a football and was carefully moved into one of the raised beds. A few other dwarf shrubs that are suitable trough subjects: Salix x boydii, a choice miniature willow, which in five years will grow approximately 30 cm tall; smaller hebes such as H. tetrasticha, H. ‘Tiny Tot’ and H. buchanani ‘Minor’ are slowgrowing enough to remain in a trough for many years; Cotoneaster congestus ‘Nanus’ will hug the side of a trough with its tiny spoon-shaped evergreen leaves on gnarled stems. Prune it back from where you don’t want it to encroach on other plants and it will be an attractive feature for many years.
TOPDRESSING
When the rocks have been positioned and the planting completed we come to the final stage of covering the surface of the compost with stone chippings, (often referred to as topdressing). Not only do chippings give a pleasing and natural finish to the whole trough but they prevent a certain amount of evaporation from the soil on hot days. They also prevent soil being splashed onto the foliage of plants during a heavy downpour of rain and discourage the germination of weed seeds. A covering about 3 cm deep is sufficient. Carefully tuck the chippings under each plant so that none of the foliage is in contact with the soil.
FINAL THOUGHTS
Ihope that this article will give some guidance and inspiration to growing alpine plants in troughs and sinks. There are no hard and fast rules. They come in many shapes and sizes; pump troughs (with a rounded end), octagonal and corner troughs are just some of the shapes. They can be deep or shallow, huge or small. One of the most attractive I have seen was a shallow trough filled with Sempervivum at Wisley many years ago. The biggest was Joe Elliott’s Saxon stone coffin, weighing in at nearly a ton! A trough can be planted up with just one genus or even one species, Kabschia saxifrages or Cyclamen for example or, as already mentioned, Rhodohypoxis.
You could plant one up with alpines from one continent or region (America, New Zealand, Mediterranean etc.) or of one family (Compositae, Scrophulariaceae, Leguminosae etc.) I have mentioned only a few of the many plants that are suitable. You will find many others that will grow and flourish much better in a trough than anywhere else in the garden. You will probably not stop at making just one trough; become hooked and before you know it you will have a dozen or more. Your planted troughs will intrinsically appeal to friends and relatives who will covet your creations and may even persuade you to make one (or more) for them. I am sure you will derive great pleasure and a justifiable sense of achievement when you stand back and see how appealing your collection can be.
A large stone trough in the garden of the late Joe Elliott’s in Broadwell, Moreton-in-the-Marsh, Gloucestershire.
A large stone trough in the garden of the late Joe Elliott’s in Broadwell, Moreton-in-the-Marsh, Gloucestershire.
Click here to see larger picture.
Large stone horse trough, still in practical use at Acton Scott Farm, Shropshire.
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