For those people who are growing alpines with the intention of exhibiting competitively, an alpine house is preferable...but not essential. If you and your plants are under cover, it allows necessary work to be carried out in relative comfort, even in inclement weather.Just as much care and attention is required in late Summer, Autumn and Winter, as in Spring, when the majority of plants are in active growth. It is essential that plant maintenance is practised throughout the semi-dormant periods for it is at these times, that out-of-season aphid and caterpillar attacks often occur and the threat of botrytis is greater. More about botrytis later.
Many growers, through choice, grow their plants in a variety of situations. In frames, in raised beds, covered in Winter to deflect rain etc., or in pots, plunged in the open garden, again covered only when dormant. These methods have the advantage of keeping the plants in better character than in an alpine house, due to the fact that the plants have a much better access to the available natural light and as often happens with certain plants, they do not etiolate to distant glass. For example, it is virtually impossible to grow Androsace alpina or Campanula cenisia in an alpine house and maintain their character. They are much better suited to growing near to the glass in a frame or totally unprotected when in growth, only offering protection for the buds and subsequent flowers and against the vagaries of Winter weather.
If you are insistent upon having an alpine house, then aluminium is by far the best material to use. It is rustproof, rotproof and virtually indestructible. With a modicum of DIY skills, a hacksaw and a drill, you could custom-build your own. (Check your local supplier for standard glass sizes, as it is much cheaper to design around readily available glazing materials than it is to have the glass cut to size. Check out your local stockist for available supplies and prices of aluminium extrusions. Most of them should be able to supply you with a free brochure and price list. If you do decide to construct your own as opposed to purchasing a ready-made alpine house, then do remember to consider the amount of ventilation that will be required. The more ventilation you can afford, the better for the plants. Louvered windows offer excellent ventilation and both the sides and ends should be fully ventilated, as too, should both sides of the roof. Please bear this in mind when at the design stage.

The ideal position for an alpine house is with its length running from North to South but in small suburban gardens, it has to be sited where it will fit (Editor's Note: Geoff gardens in North West England.......you should take this into account when aspects and temperatures are mentioned in the text).

I have 3 alpine houses, each approximately 3.7m x 1.8m (12ft x 6ft), none of which is in an 'ideal' position. Two of them run from from North East to South West and one of these is a lean-to on the garage wall. By turning each of the pots 90 degrees each week (more often when in bud and flower), each plant gets its share of good light. During this 'turning' operation, scrutinise each of your plants for dead foliage and signs of insect attack and remedy as necessary. The third alpine house runs North West to South East and is heavily shaded by a neighbour's trees. This is used for propagation and for growing shade loving plants to exhibition standard.

My plants are grown in clay pots and are plunged in beds of river sand 15 to 20 cms (6 to 8 inches) deep. A sturdy framework is necessary to support this weight and this has been manufactured from reclaimed timbers placed onto brick piers. The structure which contains the plunge material being made from galvanized metal and lined with polythene sheet.

Plant maintenance is a chore that I regard as paramount for the future well-being of the plants. Throughout Autumn and Winter, a close scrutiny of each plant is vital. This is done weekly when the plants are turned. Any dead leaves and rosettes should be removed as these are the starting points for botrytis attack.
Should an attack occur, I firstly remove the infected area of the plant and then dust it with green sulphur powder. This will usually remedy the problem but if the botrytis persists, then the whole procedure is repeated. In some instances, for example when Porophyllum or Kabschia Saxifragas have been attacked, it can be sufficient to place the plants outside, completely unprotected, and allow the rain, snow, wind, frost etc., to clean up the plant. This will have no adverse effect on these plants BUT and a word of caution here, DO NOT try this method for Dionysias or Androsaces as the results will prove fatal to your treasured plants.
Winter aphid attacks can have a debilitating effect on any plant and unless action is taken immediately, it can result in the plant's demise. Effective control can be achieved by placing the plant under an upturned bucket along with a stick of Vapona (or other such proprietary brand) and leaving for 24 hours. Repeat as necessary until the attack ceases. Aphid attacks at other times of the year can be controlled by using half-dilute systemic insecticide. Varying the brand from month to month ensures that the aphids do not build up a resistance to any one particular formulation. Systemic insecticide is used each month from March to October and is watered directly into the pots.

Most people are away from home during the major part of the day due to other commitments or when taking holidays and some form of shading is necessary during the summer months.  I use one thickness of green Netlon and find this adequate. I apply the shading over the glass in May and remove it in September. Some growers prefer to 'whitewash' the glass (Coolglass is one such brand) or use horticultural scrim, both of which are equally effective. The majority of my alpines have finished flowering by May, hence the reason for shading in May. However, in order to prolong the flowers and flowering period prior to this, I shade individual plants with pieces of card and this necessitates turning the plants through 90 degrees on a daily basis to prevent etiolation of the flowers.

Watering is probably the most difficult part of growing alpines in pots. If however the plants are grown in clay pots, plunged in river sand (NOT builders sand), it is far easier to control. By keeping the sand moist in winter and wet in summer, the water will percolate through the pots and keep the plants happy. Obviously, during the growing season, individual plants will require watering directly into the pot. How often? Well this is one of the great imponderables but with experience, one can see the limpness of the foliage or the opening of a cushion when the plants are desirous of a good drink. The structure of the compost also bears relation to the amount of water required and with any collection of alpines, varying composts are used. Composts which have leafmould and/or peat included will retain moisture for much longer than high cushion alpines which have a high ratio of grit incorporated into their compost and need water much more frequently than the former.  It is an emotive subject and can only be tailored to suit the plants grown by each particular individual.

I do not propose to list a variety of composts suitable for growing alpine plants as, in discussion with other growers, it is quite evident that similar results are achieved for any particular species, with widely differing composts. Suffice to say, do not have the compost too rich and incorporate plenty of grit.

Anyone who is serious about cultivating alpine plants, be it for exhibition purposes or for the garden, should consider joining one of the major Societies. Much information on all aspects of growing alpines can be gleaned from their publications and contacts can be made with other growers of similar interests.
(Editor's Note: All the major Societies are linked to The Alpine Garden and details of their services are available on the Sites Of Special Interest  page). 

PHOTOGRAPHS ACCOMPANYING THE TEXT

Dionysia lamingtonii
Primula tyrolensis
Primula aureata
Androsace vandellii
Dionysia bryoides
© Geoff Rollinson 1998

All other photographs © Alan Grainger 1998

My thanks to Geoff for opening his alpine house to us. I have had the pleasure of visiting Geoff's home many times and his plants are really 'out of this world'. If you intend to grow plants in an alpine house, or if you already do so, then I am sure this article will be invaluable to you.
Comments on this article please to The Alpine Garden