Discover the endless growing possibilities of an alpine house with our latest article by Tea Break Gardener, Katharine Woods.
Alpine houses, and other specialist plant houses, provide the perfect environment for growing alpine plants, cacti, unusual bulbs and succulents.
Find out why you might want an alpine house at home and which amazing plants you can grow if you have one.
True alpine plants spend their winters under a blanket of snow. This insulates them from fluctuations in temperature and protects them from winter wet, wind and pests.
The glass of an alpine house protects these plants in the same way – it is the equivalent of a thick covering of the white stuff.
Reginald Farrer, in The English Rock Garden, says an alpine house protects plants that spring…
“…so prematurely from the dead and sodden world, that they are almost certain, in the open garden, to be flogged to pieces by rain and battered out of their beauty, splashed with mud and obliterated, pecked asunder by birds, and nibbled into rags by the early rising slug.”
Alpine houses have maximum ventilation and light levels to recreate the mountain environment. They stay light and airy all year round.
They also need to be kept cool in summer when a traditional greenhouse could overheat. This is why alpine houses are usually fitted with shading.
Some specialist plant houses also come with benching for displaying plants in pots.
The answer to this question will depend a bit on where you live. If you’re in dry East Anglia, then what you can grow on free-draining soil outdoors will differ from what you can grow if you live in a damp valley in Wales.
This means that what needs to be grown in an alpine house in each of these places will also come apart.
Alpine growing is often a case of trial and error. Having an alpine house offers many options to nurture, protect and experiment with plants.
There are some plants which must be given alpine house protection, including many alpine cushion plants.
Specialist alpine nurseries are usually careful to specify if a plant needs an alpine house. Always check with a grower before you buy as they can advise you on the needs of the plant.
The following plants need an alpine house to thrive. If you fall in love with them, you might want to start saving for an alpine house!
Alpine house Androsace plants bear tiny flowers, shaped a bit like a primrose, above cushions of small leaves. Androsace ciliata, A. cyclindrica, A. hirtella and A. vandellii all grow best in an alpine house.
If you don’t have the luxury of an alpine house, there are other varieties of Androsace that will be happy outside.
There are many beautiful Primula plants that will grow outdoors, but some really dislike the combination of winter cold and wet. In certain species, it can even lead to rot and botrytis.
To keep these primroses looking their best, an alpine house, that keeps them cool and dry is a must.
A good example of an alpine house primula is Primula allionii, which bears stalkless flowers in beautiful shades of white, pink and red.
These are a group of alpines that form mounds of tiny leaves. Flowers are borne on thin stalks in spring.
A good example of a glasshouse-only version is Draba mollissima.
Hailing from central and southern Asia, Dionysia are classic alpine house plants.
Popular and impressive on the show bench, they are best grown in specialist conditions.
They’re hardy in an unheated greenhouse, but need the excellent ventilation of an airy alpine house to prevent botrytis. Some are easier but others are seen as a challenge even for expert growers.
Grouped displays of flowering Cyclamen in a glasshouse provide impressive interest in autumn and winter.
Many, like Cyclamen hederifolium, perform well in the garden, but a classic example of one best grown in a glasshouse is Cyclamen graecum. Many experienced growers keep them in sand plunges inside an alpine house.
This species has not only fabulous flowers, but also impressive, patterned leaves.
Whilst some growers have plant houses purely for bulbs, many will combine alpine plants with bulbs for year-round displays and spring colour.
Various forms of Tulipa, Fritillaria, Crocus, Tecophiliaea, Narcissus, Colchicum and Corydalis perform best in an alpine house.
Keen collectors design and position their plant houses around the needs of specific plants, taking into account light needs, shading, ventilation and temperature.
Keen flower show exhibitors often have more than one house, grouping similar plants together for maximum success.
A specialist bulb house, like the one below, will have good air flow and little shading to maximise the baking heat preferred by bulbs in summer.
Meanwhile, succulents or cacti need good light levels, particularly in winter, along with frost-free conditions. So, a glasshouse that houses these plants may require a heat source along with a bright winter position.
Hepaticas are different again. They need shade in summer, so will require a glasshouse that’s protected from strong sunshine.
On the other hand, Crassula must be kept above 5 degrees centigrade over winter and are not particularly fussy regarding ventilation.
The below photo shows a specialist plant house built by Griffin Glasshouses.
It houses Amanda Whittaker’s National Collection of Crassula Species. It was designed with a winter heat source and good light levels, but no specialist ventilation to suit the needs of the plants inside.
The primary reason for having a specialist plant house is to ensure plants thrive. But for many gardeners there are secondary considerations, such as aesthetics, entering shows and attractive displays.
For many, the alpine house is not just a place to grow plants that wouldn’t survive outdoors – it’s a theatre in which to stage beautiful plants throughout the seasons.
If you visit alpine houses in botanic gardens around the world, you’ll see imaginative displays of beautiful plants year-round. They are walk-in jewel boxes and celebrate the joy and variety of alpines.
The UK has many beautiful alpine houses to visit, including Kew gardens, RHS Wisley, RHS Harlow Carr, the Royal Botanical Gardens in Edinburgh and Birmingham Botanic Gardens.
Each offers fabulous seasonal displays and most contain miniature rock gardens, tufa walls, and waist-height planting so the visitor can enjoy the specimens up close.
Curating a beautiful display is something you can also do at home.
Of course the finest alpine houses are backed by glasshouses, behind the scenes, in which the plants are grown. Only the best plants in season will make it from the work-horse glasshouses to public display.
Many amateur alpine growers have similar arrangements. They use frames containing pot-grown plants which can be rotated into the glasshouse as they come into flower.
This approach will protect them from the worst of the weather whilst at their peak, to be taken to shows, or simply to be enjoyed where they’re easiest to see.
“No pleasure…is greater than a clean little house, airy and sweet, filled with clean, undamaged potfuls of Saxifrage, Iris, Adonis, and so forth, all shining in untarnished radiance…”
Reginald Farrer (The English Rock Garden, 1919).
Many growers use alpine houses to produce the best specimens for taking to flower shows, even if plants could survive outdoors.
Plants must also be taken to flower shows in pots, so would need digging out of the garden and potting for competition. Growing in pots removes this hassle ahead of a flower show.
Glass also protects prized specimens from heavy rain, wind or cold weather that may check their growth in the run up to a show. Expert growers will use a glasshouse wisely, moving the plant in and out to bring plants to peak condition just in time for a show.
If you’ve fallen in love with a particular group of plants, careful research will tell you whether you need an alpine house or other specialist plant house to grow them successfully.
You may decide that a specialist glasshouse, like the ones in this article, is worth the investment.
Dr Adrian Cooper – show secretary for the Alpine Garden Society who grows a huge range of alpines in his garden and alpine house, designed by Griffin Glasshouses.
Amanda Whittaker – for information about growing her National Collection of Crassula Species in her specially designed glasshouse, built by Griffin Glasshouses.
Linda Lane – Managing Director of Griffin Glasshouses, a family run company with origins in commercial glasshouse construction. They build bespoke glasshouses for gardeners, to high design standards with an emphasis on providing specialist growing conditions for all kinds of plants.
David Carver – member of the South Devon and Exeter AGS groups and keen alpine grower. He also has a growing collection of Daphne cultivars. David can be found on Twitter @1davidcarver