Plant of the month – July/Aug

Campanula zoysii

This is surely one of the most celebrated of all the European alpine campanulas. Popularly known as the “Crimped bellflower”, it is native to the Eastern Alps and can be found in Austria, N. Italy and Slovenia. It is highly revered in its native Slovenia and was first discovered here, by botanist Karl von Zois (1756 – 1800) and described by Dutch botanist Jacquin.

Although I have encountered this amazing species in nature, I have not seen it at its flowering best. Another day! It chooses rock fissures and is quite happy in sunny exposure as well as shade but always on its favoured limestone. If you are fortunate you may well find it at lower altitude as large boulders erode away from higher levels and plants become established, most likely from seed dispersal. This was my experience when botanising the Vrata valley, below Mt. Triglav. I yearn to visit its Locus Classicus in the Kamnik Alps and see if I can time it right, towards the end of July and into August to capture it at its flowering best spilling out of its beloved crevices. The crimped, bottle-shaped flowers vary in shades of blue and to catch the timing to perfection would be a wonderful experience.

It is a great relief that this curious species is available in the nursery trade and is not too challenging to grow. There are, however, two main causes of death over which great care must be taken. The first is the threat of slugs. I have experienced a tray of seedlings completely destroyed by slug damage. Steps must be taken to combat them in order to prevent disappointment. The second concern is a common problem with certain alpine species when excessive flowering takes place on young plants. Once plants have become well-established in a crevice between pieces of tufa/limestone or in a gritty mixture on a trough, this danger may have passed. I am still nervous at the time of flowering and will disbud or dead-head in the first season of flowering. I have found that seed-raised plants can be stronger than those propagated from cuttings, but if you wish to preserve a particular cultivar or a good colour form, the latter method should be employed.

It is possible to select attractive colour variants and one to look out for, is the pale blue-flowered cultivar raised by Brian Burrow, Campanula zoysii ‘Lismore Ice’.

Availability:

The following nursery can be contacted to check on current availability:

Aberconwy Nursery   tel. 01492 580875

Plant of the Month, May/June

Primula reidii var. williamsii

I am certain that most alpine plant growers will be familiar with this sensational Himalayan primula. This is a beautiful variant of the white-flowering type species, native to the western Himalaya. The species, P. Reidii was first discovered by Duthie in 1883 and later collected the following year in the Garhwal and Kumaon districts of Kashmir growing in wet rocks in glacier moraine. A true alpine plant and it is not surprising that it has only hovered in cultivation.

The variant, P. reidii var. williamsii, however, is to be found in more shaded habitats at a lower altitude in W. Central Nepal. It is easier of culture and maybe this is attributed to its growing on damp, moss-covered rocks. The first discovery was made by Williams on a British Museum led expedition to Nepal in 1952. A collection was made under the number S.S.W 1770 (Stainton, Sykes and Williams). What an important introduction and surely such collections of seed or plant material should be applauded, both then and today, when carried out by responsible parties with the necessary permits. This plant has stood the test of time, while several other species from this notoriously challenging of primula sections, Soldanelloides, have fallen by the wayside.

The outstanding quality of this plant is not only the fact that it CAN be grown, but the fact that it is easily propagated from seed and has the most sumptuous of lavender-blue flowers with the bonus of a very special sweet scent, accentuated as evening approaches, to attract night-flying moths. I say lavender-blue yet this variant also produces pure white flowers, which may have come about soon after its introduction when it will have crossed with the true species (white-flowering). In my experience the white gene is dominant and if the blues are not selected, the white will, over a period of a few years push out the lovely lavender-blue. A simple word of warning! Both coloured flower forms have the same lovely fragrance.

I have been successful growing this plant in a trough or rock pocket in a cool, partly shaded position. An acid mixture, rich in humus, but well-drained will suit this primula, best. During the growing season a lengthy hot spell can kill off plants and care should be taken to water plants, first thing in the morning or late evening and offer plants some extra protection in the form of dead bracken or a similar material.Propagation could not be simpler as an abundance of seed will set on healthy plants. As soon as the seed capsules have ripened, harvest them and place the stems and place in a secure envelope (the seed is very fine!). I would sow it during the winter months and be careful not to sow too thickly. Keep the pricked out seedlings in a cool spot away from the attention of slugs. Grown on in a traditional manner, young plants will flower the following year. What a joy!

Primula reidii var. williamsii received the highest award, an FCC in 1965  from the RHS, as an alpine plant for exhibition.

Availability: Edrom Nurseries: www.edrom-nurseries.co.uk
Kevock Garden Plants: www.kevockgarden.co.uk

Plant of the Month, Mar/Apr

Corydalis solida ‘Dieter Schacht’

Early spring in the garden often highlights a mass planting of snowdrops, Muscari, aconites, crocus and assorted daffodils where the colour range seems to omit the soft pinks, salmon pink and vibrant reds. A favourite group of plants, the highly diverse range of Corydalis solida forms will fill this void. Specialist nurseries now offer a number of cultivars, some of which have recently been given the coveted RHS award of garden merit (AGM).

I will feature just two of these cultivars, the best “doers” which are also currently available in the trade. The first is Corydalis solida ‘Dieter Schacht’ which originated amongst a batch of seedlings raised by the Curator of the alpine department at the Munich Botanic Garden, Dieter Schacht. I made a selection of a few of the best seedlings and named the strongest and, in this case the finest of the shell-pink, flowering forms. Having purchased a pot of this cultivar, it should be planted in a sunny, well-drained spot amongst kindred species such as miniature narcissus and Crocus chrysanthus cultivars. Congested clumps of little tubers will soon establish and can be lifted and divided, carefully during the dormant season in August/September, to allow for distribution of plants. If this or other chosen cultivars are allowed to seed about, expect some variation!

The origin and subsequent introduction of this variable species is a little confusing. They are distributed, in the main, in a rather restricted area in Romania and may have been introduced in the 1920s. They found their way to the Munich Botanic Garden in the 1940s and I brought some forms back to the UK after my apprenticeship there, in the 1970s. They have been further developed in recent years and such has been the proliferation of names that botanist, Dr Alan Leslie recommended Group status: Sunset Group for the red shades and Sunrise Group for the pink-coloured forms. A sensible approach, indeed.

If C. ‘Dieter Schacht is the best of the Sunrise Group, then I would choose an equally fine cultivar from the Sunset Group, C. ‘George Baker’ with crimson-red flowers. Both have been awarded the AGM.

Availability:
www.kevockgarden.co.uk
www.edromnurseries.co.uk
www.pottertons.co.uk

Plant of the Month Oct/Nov

Gentiana ornata

This autumn-flowering species of gentian was first discovered by Danish botanist Wallich in 1820. He had discovered it in the Gosain Than, C. Nepal. It may have remained in relative obscurity, from a horticultural point of view, until 1930 when it was introduced through Thomas Hay of the Royal parks and Gardens, London. On this occasion the field notes show that this collection was made at 14,000ft in Chocgo, Nepal. The species flowers during the months of September and October in its native Himalaya and this time period can be mirrored in cultivation, too.

Gentiana ornata will rank as one of the most attractive of the compact-growing, autumn-flowering gentians. It is easy of culture and is best grown in a trough or raised bed where attention to detail can be given regarding its need for a cool position and a freely drained substrate. It forms a neat mat with congested rosettes and, at flowering time the terminal flowers are pale blue, solitary and sessile. White flowering forms have also been noted in nature, most notably in the Gosainkund, C. Nepal although the species is also native to S. Tibet (S. Xizang), Bhutan, E. Nepal and Sikkim. In C. Nepal it can be found growing with the equally beautiful and perhaps more challenging Gentiana depressa.

Successful culture depends on it being given a cool position with good light, an acid well-drained growing medium and never allowed to dry out during the growing season. Well-flowered mats should produce some fertile seed and this provides the best means of propagation, but older mats can be lifted and divided during the spring before the rosettes break into growth. It associates nicely with some of the compact growing species of Cyananthus such as C. delavayi and macrocalyx ssp. spathulifolius.

The availability of the rarer gentian species is limited and enquiries should be made through the specialist alpine nurseries who advertise in the AGS and SRGC Bulletins.

Plant of the Month Aug/Sep

Gentiana Shot Silk

Gentiana ‘Shot Silk’

Here is an autumn-flowering gentian, widely available in the nursery/garden centre trade and one well within the scope of general garden cultivation across the UK. This gentian was raised by Keith Lever of Aberconwy Nursery and received an AM from the RHS in 1991. Many fine cultivars of autumn-gentian have received names and shown great promise, only to fall by the wayside due to a fatal attack from rust or the ravages of red spider mite. This one has stood the test of time and looks likely to hold its own against some further raisings from the same “stable”.

Its large flowers are funnel-shaped and held upright and a dark, royal-blue shot through with a violet sheen. One of its strong points is its compact nature, in stark contrast to some of the old-established forms of Gentiana x macaulayi and the late-flowering species G. sino ornate. I am certain that this cultivar bears some strong blood from the rarely offered G. veitchiorum which has been represented by the hybrids: G. X stevenagensis ‘Bernardii’ and Frank Barker’. The flowers may well open towards the end of August and will continue on through September and early October in a bold planting.

It is a strong grower and increases well, best suited to a lime-free soil and given a moisture-retentive soil in an open sunny position. Autumn-flowering gentians of the Series Ornatae are likely to flower poorly if afforded too much shade and those most closely related to G. sino ornata appreciate plenty of supplementary moisture. I prefer to grow these gentians in a well-prepared bed containing plenty of acid mulch. Plants associate well with Sedum cauticolum, Crocosmia ‘Solfatare’ and Kniphofia galpinii ( syn. K. triangularis). They make a great show in a bed planted at the base of a Liquidambar or Nyssa sylvatica.

Propagation can be carried out by lifting established (3 year-old) clumps in March/April. The dormant rootstock can be carefully shaken and the strongest root thongs retained whilst the tiny spindly ones are discarded. The strong ones should be re-planted in fresh soil about 12” to 18” (30 to 45cm) apart. The newly planted material should be well watered and not allowed to dry out during the growing season. Although the raiser can enjoy up to 68cm of rainfall per annum, I find that this cultivar performs well in the dryer climes of eastern Britain.

Availability – Aberconwy Nursery, tel. 01492 580875

Edrom Nurseries, www.edromnurseries.co.uk, 018907 713864

Macplants, www.macplants.co.uk, 01875 341179

Plant of the Month – July

Erigeron ‘Canary Bird’

Here is an alpine plant, so well known in specialist alpine circles, that it may need little in way of an introduction, but I suspect few readers will know the true story of this plant’s introduction.

We have to go back to the year 1960 and that great “emporium” of alpine plants, Jack Drake’s Nursery at Inshriach, Aviemore.  The late John Lawson (the then business partner to Jack Drake) wrote,”we received seed of Erigeron aureus from a friend in the United States, Mrs. Birdie Pradavich. When the seed germinated and the plants eventually flowered, one seedling had a pale yellow flower.” This sterile form was eventually given the name Erigeron ‘Canary Bird’ and has stood the test of time, remaining one of the most popular of all alpine plants. It is totally hardy and this should come as no surprise as the mother plant (Erigeron aureus) can be found at soaring heights on Mount Rainier 4392m (14,411ft), a volcanic mountain in the Cascade Range, Washington State.

I can well recall offering plants whilst training at Jack Drake’s nursery, back in 1976, for £4.00 each and customers were limited to one per person at that stage! It has held this value ever since that day. I have never found it easy to propagate as the greatest challenge is to hold back its flowering potential and create some vegetative material from which cuttings can be taken. There lies a challenge to would be propagators. There are no difficulties with growing the plant. It should be planted in a trough, positioned in a sunny position and tucked in between small rocks. In order to aid establishment, I would remove a few buds in its first year, as there may be a danger that it will “flower itself to death”.

As far as propagation is concerned, as has already been mentioned, it is a sterile plant and will therefore set no seed. Established plants will produce tiny, non-flowering side shoots which can be detached with a scalpel and will readily root in a mix of washed sand and “Perlite”. The lemon-yellow coloured, daisy flowers are a delight and will reward the grower with an unceasing display of blooms throughout the late spring and summer. During the growing season I would recommend a good soaking, last thing at night, during dry spells and an occasional watering with tomato feed during the same period, to strengthen the plant. This will remain a classic alpine garden plant and is yet another cultivar raised by Jack Drake’s nursery to which we owe so much for their notable introductions.

Availability:  Slack Top Nurseries, www.slacktopnurseries.co.uk
Aberconwy Nursery, tel. 01492 580875

Plant of the Month – June

Plant of the Month – June

Primula bulleyana is one of the finest and most rewarding members of the Candelabra Balf. section of primula. It is native to North–west Yunnan in China and, although readily available as the true species, hybridises so readily in the garden that it can rapidly lose its identity.  While I will always endeavour to retain some plants, “true” to type, I am very happy to interplant it with the following species in order to create a lovely strain of hybrids, merging together to form pleasing shades of “pastel colours”: PP. chungensis, pulverulenta and bulleyana ssp. beesiana.

The true species displays flowers of a clean orange colour, while its subspecies, P. b. ssp. beesiana has purple flowers. The flowers are borne in tiers or candelabras and when grown in a damp, slightly shaded position will provide many weeks of welcome colour from late May into June. This species associates splendidly with the more vigorous Meconopsis cultivars such as M. ‘Huntfield’ and ‘Susan’s Reward’, as well as astilbe, rodgersia and bergenia.

Propagation is quite straight forward and where possible, in order to maintain vigour, plants raised from seed from true stock are recommended. Congested clumps can be divided at any time out with the flowering season. If you are not confident that the chosen site will retain sufficient moisture, I have been successful with generous mulching with well-rotted horse manure.

Plants can be obtained from:

Long Acre Plants, www.plantsforshade.co.uk
Kevock Garden plants, www.kevockgarden.co.uk

Plant of the Month, May

Gentiana angustifolia ‘Frei’

For generations, keen gardeners have sought to grow and successfully flower the alpine gentian, Gentiana acaulis. This traditional name just about encapsulates all dwarf, “trumpet” gentians. In reality the true G. acaulis is probably the acid-loving Gentiana kochiana, commonly found in alpine turf throughout the Alps. It is a wholly unsatisfactory garden plant and is best admired in nature and left well alone. The completely reliable species to grow in the garden is Gentiana angustifolia and any of its cultivars, including: ‘Frei’, ‘Krumrey’ and ‘Rannoch’. My favourite of the bunch is the first one, ‘Frei’.

Unlike its cousins, G. angustifolia is far from widespread in its distribution in the wild, occurring on limestone in the Alps of south-eastern France and a solitary location in Switzerland. It can be found in diverse habitats in nature from settled scree to fissures of limestone and it is perhaps for this reason that it is such an adaptable plant in cultivation. Its long, narrow leaves make this quite a distinct species, but it is its long flowering stems that set it apart from similar species. The flowers are borne on stems up to 7cm in length making them ideal for use as cut flowers. The flower colour is generally a vivid dark blue and there is also a free-flowering, white variant, Gentiana angustifolia ‘Alba’.

The cultivars I have recommended are all reliably free of flowering and very easily propagated, either from cuttings (from non-flowering shoots) or division of the clumps after 3 to 5 years. Propagation is best carried out from plants that are healthy and always during a damp spell when the plant is not under stress. Although gentians can be raised from seed (freshly sown), expect some variation in the progeny.

The fine cultivar, Gentiana angustifolia ‘Frei’ can be obtained from Kevock Garden Plants:

www.kevockgarden.co.uk

Plant of the Month, April

Erythronium revolutum

This species must be one of the finest and most rewarding of all the Erythroniums. I say this because of its dual-beauty created by clear pink, yellow-eyed flowers along with stunning green and purplish, mottled leaves (in its best forms). While it fails to “clump up” by comparison to its sterile cousins, I find that in ideal “woodsy” conditions (dappled shade amongst deciduous trees and shrubs with a soil enriched with plenty of well-rotted leaf mould) it will self-seed happily.

Erythronium revolutum or the Mahogany Fawn Lily, is native to N. America and enjoys a wide distribution from Vancouver Island south to N. California. In nature it flowers from March until June, while with me in East Lothian, it is at its best in April. It is a variable species both in flower and foliage and can be selected from seed. The RHS coveted Award of Garden Merit has rather surprisingly gone to the species as a whole. I say surprising as, already alluded to, this is a highly variable species and if it is offered for sale as an un-flowered seedling with an accompanying label displaying the AGM, a customer maybe perplexed having purchased a rather poor form! Perhaps I should remind readers that an AGM is awarded to meritorious garden plants as opposed to an AM or FCC which is awarded to a plant of outstanding merit as a plant for exhibition.

I can well remember fine stands of a varietal form E. revolutum var johnsonii distributed from the outstanding Aberdonian plantsman, Harold Esslemont. This form has a more splendid flower, perhaps a deeper pink than the norm, but the foliage was simply stunning with a more striking mottling. This is one to look out for, along with the named cultivar E. revolutum ‘Knightshayes Pink’. The latter choice should be propagated vegetatively.
It is possible to enjoy the most captivating drifts of this species in privately-owned gardens. Look out for opening days for the following gardens: The Savill Garden, Windsor, Knightshayes Garden and The Garden House both located in Devon. Branklyn Garden, Perth has a fine display, too.
Sources of plants:

Long Acre Plants by Mail Order, www.longacreplants.co.uk, tel: 01693 32802, Charlton Musgrove, nr Wincanton, Somerset, BA9 8EX
Kevock Garden Plants: www.kevockgarden.co.uk

Plants of the month, February

There can be no doubt that, particularly as I write this piece in the first weeks of February 2011 when still well and truly hamstrung by the wintry weather, “momentary joy”, the emergence of snowdrops and winter aconites brings hope of the arrival of spring. Rather than offering just one plant of the month, I thought it appropriate to highlight two  bulbous plants which will certainly delight the discerning gardener and beginner, alike.

My first choice is the very special snowdrop cultivar, Galanthus plicatus ‘Sophie North’. This outstanding plant was brought to the fore by Dr. Evelyn Stevens who gardens in Sherriffmuir by Dunblane. She has a quite remarkable garden with a national collection of Meconopsis, as well as a natural plantation of snowdrops in a woodland setting. I first brought a specimen of this snowdrop down to an RHS show in Westminster in 1996 from Evelyn and it immediately caught the attention of the snowdrop experts. At this time it was named Galanthus plicatus ssp. byzantinus, one of the most beautiful forms of this very distinct species originating in its native Turkey. This cultivar, which arose in Evelyn’s garden, was subsequently named in memory of one of the children killed in the Dunblane Primary School tragedy.
G. ‘Sophie North’ is a sturdy snowdrop of short stature with distinctly broad, glaucous leaves. What is so notable about the foliage is the inrolled margin of the leaf and combined with its large dumpy flowers, makes this an outstanding and choice snowdrop. Such are the crazy prices paid for the rarest snowdrop cultivars, that it is reassuring to be able to recommend one that is sensibly priced and, in my experience, a good grower and of good constitution.

My second choice is a plant that will associate admirably with the foregoing snowdrop. The winter aconite Eranthis hyemalis is native to France, Italy and the Balkan region where it can be found in deciduous woods and rocky terrain. The characteristic, yellow buttercup-like flowers are set against a frilly, bright green ruff of leaves. Winter aconites have been grown in British gardens for over 400 years and many of us will have our favourite places where they can be seen in vast sheets, seeding freely beneath deciduous trees and shrubs, often naturalised in short grass. I must point out that this little bulbous plant, for all its charming beauty, is one of the most poisonous plants we grow in our gardens.
During the past century there have been some attempts to raise hybrids between this species and its Turkish cousin, Eranthis cilicica. In 1923 a hybrid was raised by Mr. J.M.C. Hoog in Haarlem, The Netherlands and named E. x tubergenii ‘Guinea Gold’. As the botanists and taxonomists keep busy, a new name was borne and I believe the latest name for this pretty cultivar is, E. Hyemalis Cilicica Group ‘Guinea Gold’. What makes this cultivar stand out is the fact that it is completely sterile and therefore puts all its energy into forming a generous compact clump. Added to this quality is the distinct bronze-tinged foliage and larger flowers. When you purchase your plants either as dormant, dry little corms or growing plantlets, plant them out in a cool position with added leafmould or well-rotted garden compost and label clearly. Allow the plants to establish for a number of years before lifting it after flowering and carefully slicing the little gnarled corm in to a few pieces. I have it planted amongst snowdrops and Corydalis solida forms where the flowering association is a delight during the months of February and early March.
Plant availability:
Both my recommendations for February can be sourced from the following nurseries:

Edrom Nurseries, 018907 71386
Christies Alpine Plant Nursery, 01575 572977
Kevock Garden Plants, 0131 454 0660