Alternative Rock Garden and Alpine Plants

The great thing about alpine and rock plants is that they are so collectable. Like doll house furnishings, 00-gauge model trains and other small toys, it is probably their miniature stature that makes these dainty plants so desirable. However, you may catch the rock plant bug, but not the rock garden fever, in which case you can relieve your symptoms by cultivating the plants in a number of alternative situations, which I discuss here:

Sink Gardens

After true rock gardens, sink gardens are the most popular artificial habitat for alpine and rock plant collections. Once again, I recommend a visit to your local botanic garden to sec how the sink gardens there are composed. You will see wonderful miniature landscapes complete with dwarf trees, shrubs, herbaceous plants and bulbs. It is quite spellbinding and reminds me of the miniaturised landscapes of the Japanese bonsai gardens, but that is another kind of gardening altogether. Nevertheless, the aesthetic values remain the same – landscaping materials, plants and the scale of all the parts must be in harmony.

Once upon a time it was possible for gardeners to obtain true stone sinks, but the increasing popularity of this style of garden meant that demand soon outstripped supply. It is still possible to obtain stone sinks, but at an exorbitant price, and generally from antiques dealers – just to give you an idea of how far up the ladder of desirability stone sinks have climbed in recent years.

Hard on the heels of the true article came the white enamelled sinks, stripped from old kitchens in the name of modernisation (it is amusing that contemporary versions of these sinks are now offered by fitted kitchen designers). These sinks, however, can be covered in a hypertufa mix to make a passable imitation stone sink.

Making a Hypertufa Sink Garden

You will need one plastic bucket, a sack of ready-mix cement, sedge or moss peat, builder’s sand and a tub of general-purpose contact adhesive, such as Unibond.

Clean the sink, taking care to remove any trace of grease, dirt or scum and stand it on bricks to raise it off the ground.

Paint a layer of adhesive all over the exterior and over the top edge into the interior by about 10 cm/4 in. Apply it evenly but thickly and then scumble the surface with a garden hand fork.

While the glue begins to set, thoroughly mix together one part cement with one and a half parts peat and two parts sand. Then add just enough water to make a stiff, doughy paste. This is the hypertufa.

Test the surface of the glue. When it feels tacky, put on a pair of rubber gloves, take a handful of hypertufa and apply it to the sink. Apply an initial layer about 1 cm/K in thick. It should be quite rough. Work from the bottom up, taking the mix over the edge to the interior of the sink, so that when it is filled with soil there will not be any white enamel showing to give the game away. Remember to keep the drainage hole free.

Let the sink dry for a few days, then move it into position. To help it acquire the patina of age, paint it over with plain yoghurt as described above. Alternatively, you can purchase a liquid ageing compound specially blended for the job.

If you don’t have an enamel sink, you can still make a hypertufa version by using a box, of the correct size, as the mould. It is a method learned from a friend who is a sculptress; she advises using polystyrene boxes of the sort used to pack fish for market. However, you can use any size box — even ice cream cartons to make mini-sinks.

First you must wrap the box in small mesh chicken wire, moulding it closely to the sides, inside and out. This forms an armature upon which the hypertufa is shaped. Turn the box raj upside down and poke a large drainage hole through the bottom of the box. You can make several holes and keep them open by plugging them with short lengths of bamboo, which can be removed after the hypertufa is dry. Mix the hypertufa as before, but make it somewhat stiffer by using less water. Apply the hypertufa to the outside of the box first, patting it on evenly in small handfuls; try to keep it a uniform thickness so that it will dry evenly. Leave to set firm before inverting the “sink” to complete the inside coating. When the inside coating is completed, leave to dry thoroughly before removing the bamboo plugs, if used, and then paint with yoghurt to encourage lichen and so on.

Drainage in a sink garden is easier to control since the whole environment is artificial. First of all, though, remember the rule about positioning and site the sink in a sunny, open place. Do not set the sink directly on the ground, but instead prop it up on bricks. The sink should slope very slightly in the direction of the drainage hole to encourage water run-off. Cover the hole with broken crocks and put a layer of gravel in the bottom of the sink. Fill with compost (an extra handful or two of sharp grit added to the compost will further aid drainage).

Position the selected rocks, partially burying them just as you would for a full-scale rock garden. Keep it simple, however, and don’t use so many rocks that it looks like a heap of rubble in a box. One or two perfectly formed specimens will suffice; choose them for their interesting shape or texture. Put in the plants and then cover the soil surface with a layer of washed gravel. Do not fill it to overflowing, but leave a gap of at least 2.5 cm/1 in between the surface of the soil and the rim of the sink.

Alpine plants need water at their roots and in a sink garden this can be difficult to achieve as water tends to run off the surface of a well-planted sink. This, however, can easily be overcome by building in a submerged irrigation outlet, this is a length of plastic drainpipe, about 5 cm/2 in in diameter, ‘planted’ in the corner opposite the drainage hole (it should be only as long as half the depth of the compost). Water into this tube and the roots will be well-irrigated. The top of the tube can easily be concealed by a small rock plug.

26. February 2012 by Dave Pinkney
Categories: Alpines, Featured Articles, Plants & Trees, Rockery Garden | Tags: , , , | Comments Off on Alternative Rock Garden and Alpine Plants

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