Plantsman’s Corner: Darmera peltata

 

I was walking in Salzburg University’ s small but quaint botanical garden a while ago when I stumbled upon two young gardeners (students?) cutting back a big patch of Darmera peltata.  My initial thought was why destroy such a beautifully established plantation, but as kept  walking along the waterway that separates the garden in two, I realized that it had maybe taken over too much ground and needed to give space over to others.  Darmera is not an invasive plant but it certainly knows how to fight its ground. It is very competitive and precious little can dislodge it once established. I left a clump unattended for more than 10 years in a field and when I went back, nothing had succeeded in growing through it, not even tree saplings.

The Darmera rhizomes are very tightly wound together that weeds and other plants have a difficult time establishing a foothold in an established Darmera colony.

This giant saxifrage used to be known under the descriptive name of Peltiphyllum (from the Greek peltos, shield, and phyllos, leaf) for its beautiful round plate-size leaves (glossy and slightly concave, unlike the similar but matte and convex Astilboides).  It had just changed name when I encountered it for the first time as a burgeoning gardener twenty years ago.

Darmera is a great bog plant that offers a good contrasting shape to reeds, irises, cattails and other linear marsh dwellers.  It is very easy to grow and although it relishes mud (even if it won’t survive with its rhizomes submerged in water), it will grow happily in ordinary garden soil. It will grow in full sun if the soil is damp, but prefers shade during the hottest part of the day. Although the plant is amenable to drier conditions, the foliage can start to look tired early on and flowering is diminished considerably. Darmera is normally grown as a foliage plant and advertised as such, but under auspicious conditions flowering is abundant and a beautiful sight.

Early in spring, its large pink umbels emerge from the mud on tall crimson stalks.  It is a welcome burst of life at a time of year when little else is out in the bog garden. I have been hopeful to find a white form somewhere but thus far none has materialized.  Perhaps if one went scourging its natural habitat on the West Coast of America in April, one might get lucky.  I haven’t come across a variegated sport either. The only variation I am aware is of a dainty dwarf form aptly called ‘Nana’.  I cannot establish how it originated but it has been around for a long time in the United Kingdom.  Despite its long period of cultivation, ‘Nana’ remains a rarity as it is a very slow growing plant.  Unlike the species, it needs a rich humid spot to do well and does not take kindly to dry conditions. Yet ‘Nana’ is a darling plant that fills a niche since most wetland plants are too aggressive and/or invasive for small ponds.  Its foliage also takes on colourful shades in the autumn more readily than the species and it is often ablaze with golden yellow and red in October here.

Darmera peltata ‘Nana’

Both the species and its dwarf form will take a few years to reach their full potential.  One can expect the foliage to be much shorter and smaller the first year and sometimes even the second year after planting. Darmera is not a plant that needs dividing often, mine has been in the same place for nearly 20 years and retains all its vigor.  Some books say that it gets thin in the center after a while, but that’s not my experience or what I have observed from other gardens. New rhizomes seem to fill gaps made by old ones that die out and the clumps remain dense for very many years.

Darmera peltata is one of the rare herbaceous perennials whose foliage will turn beautifully coppery red in autumn.

As I looked at the Darmera removal operation in Salzburg, a second thought came to my mind.  These gardeners were going to need a lot of will power to dig this network of rhizomes after they finish cutting back the foliage.  They did not seem very enthusiastic, let’s hope there was machinery available nearby.

~ Philippe Lévesque

Plantsman Corner: Salvias of Slovakia

Seeing garden plants in the wild is always a pleasant, if not eye opening, experience. Familiarity is heartwarming, but one can also learn much from observing the immediate environment in which plants grow before tailoring our gardens to suit them once we return home.

Three of the most commonly seen salvias in Slovakia are Salvia glutinosa (upper left). S. nemorosa (bottom left), and S. verticillata (right). All species are forebears of our garden plants that are now popular in naturalistic gardens.

I spent this past summer in Slovakia, a mountainous country situated in the hearth of Eastern Europe. It is a place of great biodiversity, and I enjoyed admiring the flora and botanizing. Although a wide array of plants is well represented, it is the wild sages (Salvia) that largely impressed me. They are ubiquitous and widespread throughout the country. Owing to their resilience and adaptability in disturbed habitats, salvias have an advantage over other species in the agrarian landscape here.

The first Salvia I encountered was Salvia nemorosa. It is common in central and southern Slovakia, growing in meadows and disturbed areas. Salvia nemorosa seems to love roadsides and a trail of purple often accompanied me on my peregrinations down to Austria or Hungary. Its flowering is a long affair, and even if it had been in bloom for some time since my arrival in early July, the flowers are still going strong as I pen these words at the end of August. The color is consistently a dark magenta-purple in the wild, although considerable variability appears in cultivation. Numerous cultivars have been selected for size and color, ranging from the diminutive blue ‘Marcus, scarcely a foot tall, to the tall pink ‘Amethyst’, towering over 3 feet.

Another cultivar worth mentioning here, but rather rare in North America is ‘Pusztaflamme’, an aberrant mutation with branched spikes of flowers that form a cone-shaped head. One presumes it must have been found in a meadow in Hungary since puszta, (pronounced ‘pussta’), is the Hungarian word for prairie. ‘Pusztaflamme’ is also known as ‘Plumosa’, a name that describes well the chenille-like texture of the flowers.

Salvia nemorosa ‘Caradonna’ still remains one of the best selections as seen here in late May at Chanticleer.

Although any Salvia nemorosa is deserving of a place in the garden,  some sort are more dramatic than others. ‘Caradonna’, bred by Beate Zillmer of Zillmer Pflanzen in Uchte, Germany, is perhaps the most famous for its narrow spikes of dark purple flowers on black stems, an intense, but luminous combination.

Another common Salvia in Slovakia is a superb garden plant that I grow with fondness and ease in Canada: Salvia verticillata. This plant seems to prefer ditches, vacant lots and meadows where I saw it bursting with surprising vigor in gravel and even in dense grass. Its hardiness probably comes from its woolly leaves that retain moisture when needed and its long taproot capable of drawing water and minerals from deep down below. I had known Salvia verticillata well as a tough plant, having used it in less than ideal conditions without adverse results. Unlike other salvias, it does not need regular division or replacement, and indeed resents being moved (although recovery will happen within a year). Unsurprisingly vegetative propagation is difficult. Luckily, seeds are plentiful and easy to germinate, including the rare white form that comes true to type. For the rather special (but somewhat gloomy) all-dark cultivar ‘Purple Rain’ (which does not set seeds), basal cuttings in spring is the best option.

Salvia pratensis, commonly known as meadow sage, colonizes open fields and meadows. It has given rise to the hybrid Salvia x sylvestris.

Fairly common in Slovakia too but only in short-grass meadows (including lawns) is Salvia pratensis. Linnaeus clearly observed the species’ habitat preference for pratensis means ‘of meadows’. Although Salvia pratensis comes in a variety of colors in gardens, the ones I saw flowering were all a particularly dark purple color. Flowering was not abundant in late summer because Salvia pratensis is a spring-blooming species. The few I saw flowering already had been mowed down and were on their second flush of flowers (an observation that I will not hesitate to put in practice). Although there was no color variation, the intensity of the color –the shade that my camera unfortunately refuses to capture as it should – impressed me. In the garden, Salvia pratensis does occur in various shades of white, pink, or purple, as well as bicolored. This species is usually propagated from seeds because clumps do not increase fast and therefore yield little divisions, but outstanding cultivars are occasionally propagated vegetatively from basal cuttings or tissue culture. One such example is the outstanding ‘Madeline’, a bicolor blue and white selection from the Dutch nurseryman and designer Piet Oudolf. Oudolf too has introduced a hybrid between Salvia nemorosa and S. pratensis (hybrids are now known as S. x sylvestris), ‘Dear Anja, in honor of his charming and eccentric wife. It is a luminous plant with blue flowers born out of dark magenta calyxes. If I were forced to choose only one salvia, ‘Dear Anja’ would probably be it. Unfortunately It is a difficult plant to propagate and has thus far remained rather elusive.

Salvia pratensis withstands the competition with the grass well.

The last Salvia species I encountered on my walks in Slovakia less common and only in hedgerows and forest edges (sometimes even deep into the forest itself), was the lovely yellow Salvia glutinosa. I was surprised to see it in the shade since it has always grown well in full sunshine in my Canadian garden. Perhaps moisture is a deciding factor since Slovakia only gets half the rain we receive at home. Salvia glutinosa is a beautiful plant and one of my favorite salvias with its large heads of pale yellow flowers and its hastate foliage. It is the European answer to Japan’s Salvia koyamae, which coincidentally prefers partial shade. I look forward to trying Salvia glutinosa on the edge of our woodland, perhaps amongst Aconitum uncinatum or Actaea.

~Philippe Levesque and Eric

Plantsman’s Corner: Glaucidium palmatum

This week sees the debut of a new column Plantsman Corner, which will be penned by horticulturist and plantsman Philippe Levesque of Balmoral Gardens. Philippe gardens and manages a nursery in northern New Brunswick, Canada. The column will feature uncommon garden plants, the first of which will be Glaucidium palmatum. 

 

Pink Japanese Glaucidium (Shirane-aoi) and Yellow Kibana no komanotsume (Viola biflora), Meiji period, circa first decade of 20th century (Image courtesy of Harvard Art Museums/Arthur M. Sackler Museum)

 If you type the name Glaucidium in a search engine on the web, you will get images of one of two delightful things : either a cute little owl or a beautiful Japanese woodland plant. Indeed, both share the same scientific name derived from the Greek glaukidion, meaning to ‘gleam’ or to ‘glare’. And whilst the pygmy owls do have glaring eyes and are as cute as they get, today, it is of the gleaming qualities of one of the loveliest of all spring-flowering perennials that I want to talk about, the Japanese woodland poppy.

The common name of this plant, although erroneous in the botanical sense – it is a ranunculus – is evocative. Its flowers are composed of four crepe paper petals that flutter above pale green foliage like wide open shirley poppies. But unlike the promiscuous poppies that seed about with abandon, Glaucidium is a restrained woodland rarity. It is localized even in its native Japan, where it grows in a few open woodlands of Hokkaidō and Honshū. Ever earnest in their appreciation of native flora, the Japanese revere Glaucidium as shirane-aoi, meaning “hollyhock of Mount Shirane”, and a Shirane-aoi wo Mamoru Kai (Shirane-aoi Conservation Group), funded by Nippon Paper Industries, was established to preserve populations from being extirpated by deer. This woodlander is very amenable to cultivation, but slow growing. It used to be extremely rare in gardens here in North America, but has become readily available from recent Japanese imports of seeds and plants.

The species is a lovely shade of mauve and there is a coveted pure white form (var. leucanthum). Pink selections are occasionally seen but are often just a washed out form of the mauve one and they lack the ethereal qualities of the other two in my opinion. Remaining so far elusive are the mythical red and double forms, no doubt lurking in one of the specialized nurseries in Japan but not yet available, to my knowledge, in the West.

Glaucidium is never cheap and never will be because its growth rate is very slow but if you are patient enough, it is not difficult to grow from seeds. These seeds should ideally be fresh from the same year. They can be allowed to dry in the oddly-shaped pods before harvesting but they should be planted the same autumn and left outside (or in the refrigerator) to vernalize over winter. If planted as such, they will germinate like cress the following spring. Older seeds might take two years to break dormancy. They are a joy to see germinating, two fat cotyledons bursting out of the ground, but then disappoint rather, since they do nothing more for a whole year. I have never managed to coax them into more growth until the following spring when they usually come up as a couple of real leaves. If fed well and one is extremely lucky, it is possible to get a first flower in the third year, but usually that only happens the fourth spring. Once planted in a suitable place, the plant establishes slowly and eventually grows into a large clump.

In the garden, Glaucidium makes a great companion to other spring woodlanders. We have it planted next to Uvularia grandiflora ‘Pallida’ and amongst Erythronium oregonum for a pastel display.  The only downside to this last companion is that it leaves a gap when it goes dormant in summer. If you are concerned by this happening, you could plant it, as we have done with the white, in a carpet of maianthemum biflorum, a native of our woods.  There is a break of colour in summer  with this combination, but we don’t mind this since the foliage of Glaucidium is attractive enough and its curious seed heads are comical.  And we know that when autumn comes, we have Kirengeshoma palmata and Chelonopsis moschata nearby to delight us with their dangling bells.

In terms of cultivation, Glaucidium is not a difficult plant to please. Deciduous shade and a well-drained humus-rich soil is what it likes best but it’s forgiving for a woodlander. The only thing one should stress that it is not a bog plant that thrives in permanently wet soils. Probably more people kill their Glaucidium through excessive watering than from neglect. It actually can take dry soil with admirable aplomb and can compete with tree roots once established. It doesn’t like the heat very much, but may pull through with partial shade and cool soils. It might go dormant prematurely, but will emerge again the following spring. Successful cultivation tends to be north of Washington, D.C., U.S.A. as summer temperatures in the Southeast US are too high. Here at Balmoral Gardens, the worry is more the winter cold. Temperatures below -25C can prove lethal and so and so we protect our plants with a mulch of leaves in November, before the first snow. It is still patiently sleeping under a receding white blanket as I write this note, and it is with great anticipation that I await its joyful return in a couple of weeks’ time.