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Alpine and Rock Garden team blog

The Alpine and Rock Garden team looks after a fantastic range of plants from the world’s mountain ranges. This blog includes stories about individual plants, growing techniques and trips to see alpine plants in the wild. You can visit plants from Kew's collection of alpines in the Davies Alpine House, the Rock Garden and Woodland Garden and read this blog to find out how the team gets to grips with cultivating them.

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Alpine travels in Armenia (part one)

By: Kit Strange - 13 Jun 2011
See some of the wonderful plants found by Kit Strange from Kew's Alpine team, as she travelled around Armenia to see spring bulbs in their native habitat.
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Armenia is a wonderful place to travel to look for alpines. My particular aim was to see spring bulbs, with an emphasis on irises, especially the 'juno' irises and Oncocyclus irises (known as 'onco' irises). Armenia has four different types of onco iris, which grow from rhizomes and have amazing, showy flowers, so the hunt was on to find them all. The country is very mountainous, with most places 700 meters or more above sea level. There are amazing geological features all around, which makes for great plant hunting because you find lots of different habitats in a small area, with different plants to match, all crammed in!


Geological formations in Armenian mountains

The amazing geology of the Armenian mountains


We went to find iris lycotis (also known as I. iberica subsp. lycotis) on our first day. Travelling south from the capital Yerevan, where the countryside is quite flat, we started to gain altitude and then came to the site of the irises. Growing in Acantholimon scrub, these gorgeous flowers just dotted the landscape like black hankies.


Dark purple flowers of Iris lycotis

Flowers of iris lycotis dotted the hillsides

The second place we found an onco iris was on the following day, as we walked up a gorge that had a large fish reservoir running alongside the road. There, sharing a very interesting habitat with lots of other bulbs like Leopoldia caucasica and Ornithogalum sigmoideum, we found Iris paradoxa, growing in an area that in early spring, would have been a stream running off the mountain. Just next to the wet habitat where we found the iris, there was a south facing slope which was as dry as a desert. This area also supported a range of different plants.


Flower of Iris paradoxa

Iris paradoxa 

Driving further south again, and the weather feeling warmer still, we pulled up by a promising looking south-facing hillside, to see if we could spot some nice plants. This habitat had some shrubby trees and lots of annuals in the grass. On quite a steep slope we spotted our third onco, Iris lineolata (I. acutiloba subsp. lineolata). Many of the clumps were quite large, with many flowers. What a beautiful sight! I could tell that lots of animals had been grazing here by the amount of droppings all around - nice food for the irises!


Clumps of flowering Iris lineolata

Iris lineolata 

We saw our last onco when we returned to the north again, and had some trips out from Yerevan. In the hills around Yerevan, if you are lucky, you may spot a lovely onco called Iris elegantissima (or I. iberica subsp. elegantissima). This was again growing in long grass with lots of annuals and pretty grasses. Sometimes in the shade of trees, sometimes out in the open. There were fewer flowers but they are large, with white standards (the upright petals) and black beards on the lower petals (falls). These spectacular flowers can be seen from far away.


Amazing large flowers of Iris elegantissima

Iris elegantissima 

We were also interested in seeing Iris caucasica, which is a juno Iris. The juno irises grow from a bulb with fleshy roots attached, the leaves are more like a small leek than an iris and the standards (usually the upright petals) of the flower often point downwards and are much smaller than the falls. This group is one of Kew's National Plant Collections and they are grown in the Alpine Nursery. We spotted I. caucasica in quite a few places. The one thing that was very interesting about this plant was the variation in habitats that we saw it growing in. They ranged from sopping wet hillsides in muddy clay, to Artemisia scrub, in almost desert conditions.


Yellow flowers of Iris caucasica on a wet hillside

Iris caucasica on a wet Armenian hillside 

It is a beautiful bright yellow flower but on first opening it’s almost green. A truly wonderful plant - even when you have to fight rainstorms to see it!

- Kit -

3 comments on 'Alpine travels in Armenia (part one)'

Alpine success at Chelsea

By: Richard Wilford - 26 May 2011
Kew's Alpine Nursery sent plants to the Chelsea Flower Show to be shown to the RHS Rock Garden Plant Committee - and three out of four received an award! Read on to see the what caught the Committee's eye.
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Royal Horticultural Society (RHS) Committees meet several times a year, including on the Monday of the Chelsea Flower Show. At these meetings growers can submit new or interesting plants to be considered for awards. The Alpine Nursery at Kew usually shows plants to the Rock Garden Plant Committee and this year we sent four species to the meeting at Chelsea: Arisaema fargesii, Dianthus haematocalyx subspecies pindicola, Conanthera trimaculata and Cyrtanthus brachyscyphus.


Kew's alpine plants ready to be taken to the Chelsea Flower Show

The plants ready to be taken to the Chelsea Flower Show early on Monday morning


About the awards

RHS Committees can give several awards to plants for exhibition. A Preliminary Commendation is awarded to a plant 'of promise for exhibition', an Award of Merit is given to a plant 'of great merit for exhibition' (not to be confused with the Award of Garden Merit, which is awarded to plants that have undergone a trial to assess their garden worthiness), and a First Class Certificate is given to a plant 'of outstanding excellence'. Two other awards are the Botanical Certificate for plants 'of exceptional botanical interest' and a Cultural Commendation awarded to the exhibitor of a plant showing 'evidence of great cultural skill'.

So how did our plants do?

The Arisaema didn't win anything this time but the other three all received awards. Dianthus haematocalyx subsp. pindicola is a small, low-growing alpine pink from the mountains of south east Europe. It received a Preliminary Commendation and also a recommendation to be considered for an Award of Garden Merit.


Pink flowers of Dianthus haematocalyx

Flowers of the award winning Dianthus haematocalyx subsp. pindicola


The South African bulb, Cyrtanthus brachyscyphus, also received a Preliminary Commendation. This plant grows in Eastern Cape, the summer rainfall part of South Africa. It has fantastic bright orange, tubular flowers and has great potential as a plant for a cool glasshouse.


The plant of Cyrtanthus brachyscyphus  Orange flowers of Cyrtanthus brachyscyphus

Left, the plant of Cyrtanthus brachyscyphus shown to the Committee,
and right, the flowers close up


The third plant from Kew's Alpine Nursery to win an award was the South American Conanthera trimaculata. This Chilean bulb is in the same family as the Chilean blue crocus, Tecophilaea cyanocrocus, and received a Preliminary Commendation in 2001. This year it was looking particularly good, with several flower stems displaying many violet-blue, bell-shaped flowers. The name trimaculata means three-spotted and refers to the three dark spots on the back of each bloom. This year it gained an Award of Merit and also a Cultural Commendation. The second is especially pleasing as it is awarded to the grower of the plant and is recognition of the horticultural skill of the staff in the Alpine Nursery at Kew.


Blue flowers of Conanthera trimaculata

The flowers of Conanthera trimaculata


So a good Chelsea Flower Show for Kew's Alpine Nursery!

While on the subject of alpines at Chelsea, mention must be made of the wonderful display put on by the Alpine Garden Society, which received a Gold Medal. A few Kew staff helped out in their own time with staging this stand, including fellow bloggers Joanne Everson and Katie Price.


The Alpine Garden Society stand at Chelsea

The Gold Medal winning, Alpine Garden Society stand at Chelsea this year


- Richard -


1 comment on 'Alpine success at Chelsea'

Spice up your garden with roscoeas

By: Sue Skinner - 13 May 2011
If you want to spice up your garden then take a look at the exotic roscoeas. They are part of the ginger family, but are fully hardy in the UK and flower from now until late summer.
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Roscoea is an Asian genus of 20 species, distributed along the Himalayan Mountains and into China and Myanmar (Burma). They are in the ginger family (Zingiberaceae), with rhizomatous roots that are dormant in winter. There are a number of subspecies and varieties, plus some hybrids and cultivars. Here at Kew Gardens we concentrate on the species and naturally occurring varieties. Most are grown in pots in the Alpine Nursery but some are also grown outdoors, especially in the Rock Garden.


The yellow form of Roscoea cautleyoides

Roscoea cautleyoides in the Rock Garden (Image: Richard Wilford)


When the plants come into flower, pots are moved from the nursery into the Davies Alpine House for display. Different species are in flower from May to August. The flowers look quite exotic and some people have commented that they remind them of orchids.


Flowers of Roscoea humeana

Roscoea humeana (Image: Richard Wilford)


Flower colour is generally a shade of purple or yellow but there are some white forms as well - we grow Roscoea tibetica forma alba and also R. humeana f. alba. In some the pale flowers can be nearly pink or may be so dark that they look almost black, such as R. scillifolia. There are two yellow forms in the Alpine House now: R. humeana f. lutea and the yellow form of R. cautleyoides. Here at Kew we have observed that the yellow forms tend to flower before the purple forms of the same species.


The white form of Roscoea humeana The purple form of Roscoea cautleyoides

Left, Roscoea humeana forma alba, and right, Roscoea cautleyoides forma sinopurpurea (Images: Richard Wilford)


There is one plant that breaks from this general colour scheme and this is Roscoea purpurea 'Red Gurkha' from Nepal. As its name suggests, this plant has striking red flowers, sometimes with narrow white streaks on the lower petals. The stems are also flushed red in some forms.


The bright red Roscoea 'Red Gurkha'

Roscoea purpurea 'Red Gurkha' flowers in July and August (Image: Richard Wilford)



Here at Kew we repot the Roscoea collection in late January to early February, in a moisture retentive but well-drained compost, then plunge the pots in sand in an outdoor frame. The pots are watered in, then only the sand is kept damp until the first signs of growth in spring. Once they are in full growth they are kept well watered and shaded from the sun on hot days. Between the time the foliage dies back in autumn and repotting takes place in winter, both pots and plunge sand are kept completely dry. 


Repotting roscoeas The Roscoea frame in the Alpine Nursery

Left, repotting roscoeas in January this year (Image: Graham Walters) and right, the Roscoea frame in the Alpine Nursery (Image: Richard Wilford)


We find most species propagate readily from offsets but they are also quite easy to propagate from seed, although this does mean it is longer before they reach flowering size. 

- Sue -


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The Rock Garden in full bloom

By: Richard Wilford - 21 Apr 2011
The recent warm, sunny weather here in London has brought a whole range of plants into flower on the Rock Garden at Kew. Read on to see some of the highlights.
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The Rock Garden at Kew Gardens is home to alpines and Mediterranean climate plants from around the world. It usually reaches its glorious peak in May but the weather we have had recently has brought the flowering season forward by a week or two so there is already plenty to see.

A view of Kew's rock garden this week

A view of Kew's Rock Garden this week

Among the flowering plants you can find here are several peony species. Most do well in a free draining soil and sunny position like the following species, Paeonia anomala subsp. veitchii, sometimes called just P. veitchii. This specimen was collected as seed on a Kew expedition to Sichuan, China, in 2003.

A peony flowering on the rock garden at Kew

Paeonia anomala subsp. veitchii on the Rock Garden

There are plenty of irises in flower too, especially the 'bearded irises', which have a tuft or beard of hairs down the centre of their lower petals. They grow from thick rhizomes that are planted near the soil surface. The next photo shows the dark purple Iris sabina, a little known species from central Italy, near the town of Palombana Sabina, from which it takes its name. In front is a pale form of Scilla peruviana, collected as seed in Tunisia in 1989. This scilla is not uncommon in cultivation but normally has deep blue flowers.

Scilla and iris flowering on the rock garden

Iris sabina behind a group of Scilla peruviana

One more highlight for now is the showy blooms of a monkey flower, Mimulus naiandinus, endemic to central Chile. This has seeded itself into rocky cracks and is in full flower now. It has been in cultivation in the UK since the 1970s but usually under the name 'Andean Nymph'. Only in 2000 was it given a species name, and was described in Curtis's Botanical Magazine.

A monkey flower on the rock garden

Mimulus naiandinus flowering on the Rock Garden

These are just a few of the wonderful plants you can see now on the Rock Garden at Kew. Over the next few weeks more and more will bloom so come along and explore the twisting paths and rocky ledges of this spring garden highlight.

A general view of the rock garden

A general view of Kew's Rock Garden

- Richard -

1 comment on 'The Rock Garden in full bloom'

The parasitic purple toothwort, Lathraea clandestina, is flowering now.

By: Richard Wilford & Katie Price - 29 Mar 2011
The purple flowers of the parasitic Lathraea clandestina, known as purple toothwort, mysteriously sprout from the ground in the Woodland Garden.
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The Woodland Garden at Kew, around the Temple of Aeolus, is beginning to reach its spring best, with a range of bulbs and other woodland perennials flowering in the spring sunshine. One of the more unusual looking plants is a parasite known as purple toothwort, Lathraea clandestina. This species is totally dependent on the food produced by other plants to survive so it is called an 'obligate parasite'. It has parasitised the largest tree in the Woodland Garden, the black walnut, Juglans nigra, and the flowers sprout from the ground around the base of this mighty tree.


Purple toothwort flowering at the base of the black walnut tree

Purple toothwort (Lathraea clandestina) at the base of the black walnut


Lathraea clandestina is not native to the British Isles but was introduced in the second half of the nineteenth century and first came to Kew Gardens in 1888.  It grows wild in Belgium, France, Spain and Italy but has become naturalised in Britain and even New Zealand. There is a British native species, L. squamaria, the common toothwort, but it is not as colourful as this species.


 Purple toothwort in the woodland garden

The flowers of purple toothwort (Lathraea clandestina) can appear some distance from the host tree


The easiest way to introduce L. clandestina to your garden is from seed scattered around or mixed in the soil, near a suitable host plant. It normally parasitises poplars and willows but has also been found on a number of other trees and shrubs including maples, yew, rhododendrons and alder. In early spring the flowers appear out of the ground. They are pinkish purple hoods that form dense clumps, sometimes a fair distance from the base of the tree on which they are living.


Flowers of the purple toothwort

Flowers of purple toothwort (Lathraea clandestina)


Being a parasite, purple toothwort doesn't have any green leaves for photosynthesis, and after setting seed it disappears from view. It connects to the root system of its host, often deep down in the soil. Like many parasitic plants, feeding off another plant doesn't seem to have a detrimental effect on the host, and this strange species makes a fascinating addition to the woodland garden flora.


- Richard & Katie -

4 comments on 'The parasitic purple toothwort, Lathraea clandestina, is flowering now.'

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About us

Looking north towards the Davies Alpine House from the Rock Garden

Several people contribute to the Alpine and Rock Garden Team blog. Richard Wilford is the Collections Manager in the Hardy Display Section at Kew. His responsibilities include all the areas where alpines are grown at Kew Gardens. The three team leaders, Joanne Everson, Graham Walters and Katie Price, each have their own particular parts of the Gardens to look after. Between them, these four experts have over 55 years experience of growing alpines.

Alpines at Kew Gardens are not only grown to create colourful and informative displays, they also play an important role in the research Kew carries out around plant naming, classification, biodiversity and conservation.

Mountains are found on every continent and each range has its own unique alpine flora, but these plants are under threat from climate change. As temperatures rise, alpines are forced higher and will eventually have nowhere to go. The alpine collections at Kew are studied to help us all understand the mountain flora better and make informed decisions about protecting its future.

"Probably the most beautiful glasshouse in the world is the Davies Alpine House at the Royal Botanic Gardens Kew", John Hoyland, Gardens Illustrated, April 2011

Richard Wilford has written a book on alpines, 'Alpines from Mountain to Garden', published by Kew Publishing. You can buy it in the Kew shops or from

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