Gentiana depressa

One to look out for, Autumn 2016

Gentiana depressa

gentiana-depressaOf all the truly choice, high-alpine Himalayan Gentian species that are available in the horticultural trade, Gentiana depressa fits the bill. This species, despite its availability is still quite demanding of culture and I have not found it to be long-lived in the open garden. On occasion I have admired in awe, large pans of this species in a friend’s alpine house or taking pride of place on the Show bench! Part of me (still wearing my nurseryman’s cap) thinks it is time that such a plant should be knocked out of its pan after flowering and when starting into growth and divided up into a multitude of little plants ready for the nursery frame.

Understanding the plants habitat in nature will determine the best spot and conditions for growing it. Gentiana depressa can be found in the Himalaya from Central Nepal to S.E. Tibet ascending to true alpine limits between 3350 – 4250m. In the Langtang and Gosainkund region in C. Nepal it may be seen growing in large colonies growing on acutely drained grassy banks and hummocks where it forms tufted rosettes with spreading stems that pop up at least 15cm from the basal roots. In nature it flowers in October (a little earlier in the UK) with delightful upturning pale blue or greenish-blue, broadly bell-shaped flowers sitting neatly in the rosettes of foliage. Occasional white flower forms may be seen in the wild as well as hybrids with the equally beautiful G. ornata.

Recognising that this high altitude species enjoys fine drainage and clear air movement will determine an open position in the garden. Winter snow cover demands that we offer some winter protection from the vagaries of our winters and give it a cloche cover. I would plant it between stones in a well-drained mixture containing plenty of leaf mould. Propagation can be carried out from saving seed as well as taking cuttings from non-flowering shoots or division of established clumps.

Availability:

Aberconwy Nursery, 01492 580875

One to look out for – Summer Alpines of Distinction

Geranium argenteum

A few alpines give me a real thrill, with or without flowers. The silvery foliage of this species, formed over lax clumps is visible throughout the growing season and is amply enhanced at flowering with its soft shell-pink flowers with lovely veining.

Geranium-argenteum This is an easy alpine plant in terms of its cultivation and all it asks is an open, sunny exposure and a freely drained soil. The species can be found on limestone in nature and whilst it in no way needs this alkalinity in the garden, I will always try and wedge plants between pieces of Dolomite rock in a raised bed or rock garden. I have found this lovely geranium growing on the alpine grassy lawns on the summits of Monte Baldo high above the eastern shores of Lake Garda, N. Italy. On closer inspection the deep and tangled tap roots are delving into the alpine turf amongst rocks, always ensuring the necks of the plants are well-drained. It is a precious sight indeed, flowering with alpine Forget Me Not (Myosotis) and Daphne cneorum.

Geranium-argenteum-3---CopyIn the garden I would recommend avoiding any overhanging plants to compete with the clumps, thus avoiding needless die-back. In order to maintain purity of form from seed-raised material it is important not to plant either Geranium cinereum or G. subcaulescens nearby, as the resulting seedlings may vary due to hybridisation. If you are growing an especially fine form, this may be propagated by taking short cuttings after flowering and utilising a sandy mix with some added Perlite. Care must be taken to look out eagerly for seed and to catch it before it pops – “practice makes perfect”! I like to have some small paper bags at the ready and as the seed ripens it can be collected and the process repeated over the weeks, as ripening seed can take a while!

Geranium argenteum occurs sporadically in the Eastern Alps with an impressive outpost in the Julian Alps, Slovenia and in the southern Dolomites. It is rarely seen in nursery catalogues, but should certainly be sought out.

Availability:

www.slacktopnurseries.co.uk

Ranunculus calandrinioides ‘Dwarf Form’

In my earliest days of growing alpine plants I can recall fine plants of this North African Buttercup flowering in the early part of the year, from January onwards. This is such an early-flowering plant that some form of winter protection is essential to protect the beautifully shaped flowers from weather damage. Whilst running Edrom Nurseries I used to grow a marvellous dwarf-flowering selection of this species, given to me by the late Mrs. Sheila Maule, a great grower of choice alpine plants, who gardened in Balerno, Midlothian. She was an authority on the flora of the High Atlas Mountains of Morocco and often travelled there with her husband. The selected plant thrived in a large trough and it was planted in a freely-drained material in a sunny position. In the days of proper winters I would afford this early-flowering species a cloche cover.

The habitat in which this lovely buttercup grows is not dissimilar to the recently described Helleborus niger. Ranunculus calandrinioides grows in Cedar forest clearings or woodland fringes and on open hillsides. The species seems to have a fairly wide distribution in Morocco from the Rif Mountains in the N.E. and in a more south-westerly outpost. It is a dwarf perennial with typical fleshy roots and glaucous broad foliage often displaying a wavy edge. The flower stems may carry up to 3 flowers, white or flushed-pink in its finest forms. The stems vary in length from 6 to 20 cm and it is in the dwarf end of the spectrum where I am basing my recommendation. Plants may be grown in a deep pot and located in the alpine house or a more natural position in a deep trough allowing the deep root system to travel far in a well-drained substrate. The foliage will die down in the summer and re-appear in December.

Propagation can be carried out annually by saving seed which should be sown as soon as it can be rubbed free of its “mooring”. It may well germinate the following spring after a natural chilling. Established clumps can also be lifted (when moist and never when under stress) during the growing season and gently teased apart. Pot up the divisions in deep pots with a gritty mixture and do not allow them to become too damp. To maintain stocks of the lovely dwarf form, division will need to be employed as seedlings will vary in stature.

The species was first introduced into British gardens in 1929 and it received an AM in 1939.

Campanula ‘Joe Elliott’

From time to time in the history of modern alpine gardening, an artificial hybrid of outstanding beauty is created either by chance or by careful hand-pollination. Many of the finest plants are created by chance and it was by this method that one of the finest of all hybrid campanulas was raised. Of greatest concern are the number of wonderful hybrid plants that have fallen by the wayside, however the plant under the spotlight was raised in the 1970s at the famous Broadwell Nursery in the Cotswolds, England and still thrives in alpine plant collections today. The hybrid arose when a passing bee transferred a dollop of pollen from Campanula raineri and deposited on the ripe stigma of C. morettiana, a distinct seedling was spotted, with its shallower flowers and typical C. raineri leaves. Once isolated it grew vigorously (a sure sign of hybrid vigour) and in its second year flowered continuously from June until September. What a discovery and what sharp eyes were the possession of the late Joe Elliott and his nursery manager Ralph Haywood. So Campanula ‘Joe Elliott’ was created, commemorating its raiser. The hybrid has the same running habit as C. raineri and can therefore be propagated, both by division and cuttings of non-flowering stems.

Plants can be grown in a trough or raised bed and are best given cloche cover during the winter wet. Both parents enjoy an alkaline substrate in nature and the hybrid will respond to a material with added tufa or dolomite granules. I must emphasise the need to be vigilant against the visit of slugs at all times, they love expensive campanulas!

This outstanding cultivar has been awarded as a plant for exhibit, an A.M. in 1978 followed by the coveted F.C.C in 1981; a real accolade.

Availability: Aberconwy Nursery: Tel, 01492 580875

Iris winogradowii AGM

For many years I have grown this exquisite subalpine iris species belonging to the Reticulatae section, but I never feel as if I have found it easy or have I grown it to a sizeable clump. Right now it is increasing well! This is a rare species in nature, native to a few stations in the Republic of Georgia, or more specifically in the southern Caucasus Mountains. It is undoubtedly more common in cultivation now, than in nature – belonging in the Red Data book. It chooses to grow in dampish meadows and pockets of humus amongst rocky outcrops. Here then is a clue as to what it prefers in our gardens. An acid humus-rich soil in dappled shade will suit it best and at no time should it be allowed to dry out completely. Here is a word of warning for those who prefer to grow it in a bulb frame or in a pan in the alpine house. New root growth begins in the summer, so it should only be handled as the leaves begin to disappear.

The striking flowers are pale primrose yellow in colour with golden freckles and narrow orange crests to the falls. It is in full flower now (as I write 2.3.2014) and will reliably do so towards the end of February and early March in the open garden. As to propagation of this desirable species, established clumps can be lifted and divided as the leaves die back. Lift the entire clump being careful not to disturb the baby bulbils at the base of the clump. These rice-like bulbils can be carefully separated and scattered on a few inches of well-drained compost and then covered with the same amount of compost and finally top-dressed with grit. Label well and keep moist. As the bulbils develop, be generous with well-diluted tomato feed when the leaves are present and shortly after they have disappeared. Keep replenishing the compost until the bulbs are mature and ready for their final home. Look out for seed capsules and sow ripened seed as soon as it is ready. It may hybridise – recall the fine hybrid Iris ‘Katharine Hodgkin’ or produce some lovely variants, perhaps a fine albino!!

Availability:

Potterton’s Nursery, www.pottertons.co.uk
Kevock Garden Plants, www.kevockgarden.co.uk

Crocus banaticus AGM

This must rank as one of the most unusual and exotic of all Crocus species. It is one of the last of all the plants to flower in my garden, perhaps just preceding Galanthus reginae-olgae this year, blooming anytime from September into October (according to the season). I would always plant this species, native to the Romanian Carpathian Mountains, in pride of position. Although in nature it inhabits both open and woodland conditions, I have it planted in a cool position in a soil rich in leaf mould and protected by a few carefully positioned logs. The flowers are large and consist of delicate, long-tubed, lilac to light purple-coloured petals. The three inner segments of the flower are conspicuously shorter than the three outer ones. It also has a distinct lilac-coloured, finely divided stigma. As with many blue or purple-flowering crocus species, this one produces some fine albinos including the very attractive C. banaticus ‘Snowdrift’. In terms of propagation, established clumps of corms can be lifted and divided when dormant, whilst propagation from seed is also possible if care is taken to look out for the maturing seed capsules.

Availability:

www.pitcairnalpines.com

www.plantswithaltitude.co.uk

Rhodohypoxis ‘Great Scot’ A.M.

This cultivar will ranks as the best, red-flowered cultivar amongst this renowned genus. Rhodohypoxis flower from late spring right through the summer and are native to the Drakensberg Mts of Lesotho, producing congested clumps of corm-like structures which I have found over a period of some 30 years, prefer to have a dryish to dry, winter dormancy. R.’Great Scot’ has relatively small flowers (by comparison to such cultivars as ‘Pictus’ and ‘Albrighton’) but they are a strong, bright red colour. The name was given by the famous grower of this genus, the late Ruth McConnel. It is said that the name arose when Ruth’s husband, noticed the stunning red colour of her new seedling and exclaimed “Great Scot)!

As to hardiness – if the plants are grown in the open garden and a long hard spell of winter hits the soil when it is wet, the result will be fatal for over-wintering corms. I prefer to grow all Rhodohypoxis in troughs where the soil can be tailored to their requirements, while the troughs can also be lifted into a shed or protected in a practical way from the severity of the winter. A word of warning! During the dormant period, the over-wintering corms are a favoured diet of mice. Many gardeners grow the corms in mesh pots and transfer them from the cold frame into the garden and then reverse the process.

I would reduce watering the chosen containers from late August onwards and the troughs can then be lifted into a shed in late October/November. They will be left alone until January/February when established clumps can be lifted and carefully teased apart (some authorities prefer to divide clumps as they come to the end of their growing season in late July), however I prefer to carry this out whilst dormant. The largest corms can be placed in a trough consisting of an ericaceous, moisture-retentive mix with a percentage of soil. I would place the corms some 6cm below the surface and cover the soil with a generous layer of washed gravel. As the plants break into growth, watering can commence and the troughs should not be allowed to dry out completely. They can be removed from their place of protection and returned to the open garden in early April (according to the weather). During the growing season established clumps can be given an occasional feed of “Tomorite” (or an alternative tomato feed) to bulk up the corms. Other cultivars which I can recommend to compliment ‘Great Scot’, include: RR. ‘Pictus’, Albrighton, ‘Fred Broome’, ‘Ruth’, ‘Harlequin’ and the two species, R. milloides and R. baurii var. confecta.

Availability:

www.edromnurseries.com

www.harperleyhallfarmnurseries.com

Primula marginata ‘Casterino’

Photo: Jim Almond

An alpine garden without any forms of Primula marginata adorning it, is missing out on one of the finest and easiest of all the European primulas. The species belongs to the Maritime and Cottian Alps of Italy and France occupying  precipitous limestone (yet not exclusively) rock fissures and steep humus slopes sometimes preferring the dappled shade of trees and shrubs. It flowers in late spring ( May and early June) in nature, while its peak of flowering is usually April in cultivation. The flowers are held in an umbel of up to 10 or more and are generally lavender-blue to violet and in its best forms, as in P. marginata ‘Caerulea’ a fine clear blue or pure white with the recommended P. marginata ‘Casterino’. The flowers have a faint scent, but it is the heavily-farinose, leathery foliage that also emits a fine pungent scent and can be quite spectacular with its deeply serrated margins.

I have found that when growing the species and its many cultivars in the garden it is not fussy about the soil pH but rather, is concerned with fine drainage and loves to be wedged in between large rocks where its woody, truncated stems can delve deeply into the cooler depths of a crevice and allow the heavy umbels of flowers to shower down in all their beauty. I like to afford the plants a little shade if at all possible. To offer a calcareous substrate offers an advantage when it comes to accentuating the lovely, silver-farinose foliage which is markedly showier with a higher ph.

As well as the recommended cultivar, there are many other forms and excellent hybrids available and they are often best selected when flowering from a nursery exhibiting at one of the Spring Shows.

If readers would like to raise their own plants, this can be achieved by saving the seed and then selecting from the 2 yr old seedlings or by raising clonal material from stem cuttings taken from non-flowering shoots in early June and rooted in a sand/perlite mixture.

My recommended cultivar was a selection made by a good friend of mine, the late Bernd Wetzel, who operated a marvellous nursery in Wuppertal, Germany with his wife and family and commemorates a rich valley by the same name in Italy.

Availability: Aberconwy Nursery – tel, 01492 580875

Prunus mume ‘Beni-chidori’

A few years ago, during the month of February I was visiting a friend’s garden in Suffolk and encountered a well-flowered specimen shrub of Prunus mume ‘Beni-chidori’. Perhaps it was the striking deep, purplish-pink flowers that caught my eye in the first instance, but the sensuous waft of fragrance that met my nose was a real highlight. Due to the exotic nature of such a lovely winter/spring-flowering shrub, I asked about its hardiness. “No issues” was the reply. The species is native to Western China.

An article in the Daily Telegraph by Ursula Buchan highlighted the need for careful choice of position relative to early-spring flowering shrubs, such as the above-mentioned. She wrote “the trick with plants that flower in late winter and early spring is to find them a sheltered spot where the flowers are not seared by cold easterly gales in March (something that I am all too well aware of, here in E.Scotland), nor subjected to rapid thawing by the sun after a night’s frost”. I totally agree and what sensible advice. Not always easy to locate such a spot for our favourite shrubs that fall into this category, but well worth keeping in mind.

The Prunus cultivar under the spotlight is a cultivated form of the Japanese apricot (the species P.mume was introduced to Japan and further developed there) – hence the striking colour of flowers. I personally rather like the subtle charm of the single flowers and appreciate the modest stature of its habit, forming a small, upright tree/shrub to 3m (10ft) tall after some 10 to 12 years. The strikingly beautiful flowers are sweetly scented of almonds and typically appear in late February at the same time as many spring-flowering bulbs which can form a pleasing contrast at the base of the shrubby stems. Position it in a similar spot to subjects such as a Chimonanthus praecox so that you do not need to step far into a border to enjoy the fragrance of the flowers.

Availability:

BlueBell Nursery, www.bluebellnursery.com

Crocus, www.crocus.co.uk

Ginkgo biloba

This is a thoroughly well-known tree yet still, I feel rather sparingly planted in gardens. Often known as the Maidenhair Tree, it is certainly a unique taxon, regarded as a living fossil and similar to fossils dating back 270 million years. It is native to E.China from the Tianmu Shan, Zhejiang Provence with some living specimens now exceeding 50m in height.

This is a deciduous conifer that enjoys an open position in the garden and will eventually grow to become a big tree (reaching 20m), so a measure of caution as to choice of site! It is the outstanding autumn colour that appeals to me so much and the glowing butter-yellow tints of the foliage. Ginkgos are dioecious, with separate sexes, some trees being female and others being male. Female trees do not produce cones but rather, following pollination seeds will develop into yellow-brown fruits about the size of a large grape. The smell is awful, reminiscent of rancid butter! So, I would strongly recommend choosing a male variety. I am familiar with a number of parks around the UK and Europe that have the female version on display and the fallen fruits cause real issues for passing visitors and ground maintenance staff, alike. It is completely hardy and will always provoke some interesting conversation as to its origin.

I know of two compact cultivars available which may prove to be a sensible option for those readers who are limited to space, they include:

Ginkgo biloba ‘Globus’

G. biloba ‘Jade Butterflies’

Availability:

Bluebell Nursery, www.bluebellnursery.com

Binny Plants, www.binnyplants.com