Harvey's Blog

I was asked how I got into rock gardening. We lived in BC in the early 70‟s and spent a year wandering and working. I had a very good friend who was from the East Okanagan area, near Lumby. At that time forestry was king, and the wood came into the mills so fast the burners could hardly keep up with the waste – smoke filled the Shuswap valley so thickly it would drop the jaw of a medical professional today. No one seemed to care. Travelling east from Lumby on Hwy #6, the road climbs into the Monashee. At Cherryville, the main logging road heads north following the Shuswap River. and eventually you can drive all the way up to Revelstoke. In those days, they were still cutting old growth Douglas fir, cedar and hemlock. My friend, Jim, was building a barn in his spare time, and so he would drive in the road to find cedar butts (3` diameter and more) that were left behind and were perfect for making shakes. One trip he suggested we ride in on motorcycles to get up to the “meadows” which were accessed by a long, winding trail used to bring in cattle for a short, intense grazing season. The trail was rough but passable. There was not much to see – until the last turn; and then, it was the most perfect alpine meadow I could imagine. No cattle had arrived yet. What was there – well 40 years later I can‟t remember it all, but the sight of hillside flush with Dodecatheon pulchellum (or something like it), spiced with some Aquilegia flavescens and Castilleja sp. still lies vividly in my mind. Nothing really special, but all so perfectly arranged. It was this vision that was the inspiration. Unfortunately, you can‟t easily live in such places – 10‟ of snow will stop those ideas.

When I built our house in SW Ontario, we finally had the opportunity to act on the inspiration. Using the few stones available, the first rock garden took shape and I began looking for the plants. There were so few commercial sources in North America and though it‟s hard to imagine, there was no internet search, so growing from seed was the best choice. At that time, “shares” in a seed collecting expedition was the norm; but, this always gave the impression that distribution was based on a fraternal basis, with those deemed as superior growers, receiving preferential treatment. Jim Archibald and the Czech seed collectors democratized the process to a simple commercial exchange, which suited me better. The best aspect about rock gardening is that it is
an egalitarian experience. Money and class status mean nothing, and the Czech‟s, who suffered through 40 years of totalitarian suppression, have provided us with the most advances in both plant material and cultural methods.

I wonder where the next generation of seed collectors will come from. I can‟t say with certainty, but I can speculate it will be China. The recent Czech collections from there comprise a whole section of their own; they may become the largest section. China is still controlled with a heavy hand. It is illegal for citizens there to collect seed for commerce. Having escaped the last great glaciation, the diversity of the alpine flora is huge. A growing number of locals with expertise are interested in this flora. One wonders what ideas they will offer. This will all develop, heavy hand or not. All it takes is the inspiration of a vision.

The plants in genus Dionysia are some of the most demanding in cultural requirements that few people attempt to grow them. They possess beautiful flowers, form tight domes of tiny leaves and the intriguing habit of growing on near vertical walls with a ledge of rock protecting them from full sun and weather.

Clearly, they are not easy to please. Mostly they are grown in pots in a sand plunge bed in an alpine house, and so remain a plant for specialist growers/collectors. The few that I have grown are quite heat tolerant, but subject to rot from humidity and careless overhead watering. While we have potted specimens which we sell at the nursery or take with us to a sale, we don't list them as they are too easily damaged in transit. One day in a closed box is about all they can stand.

In our greenhouse, we overhead water as a matter of course - but carefully with the dionysia, allowing them to dry off. I have noticed that a bigger issue was that they are subject to late winter scorch - that is, the side of the plant that faces south will start growth first and the cycle of warm day temperatures w/ freezing night temperatures is too harsh for the new growth, causing those south facing rosettes to die-off. The solution is to provide indirect, bright light, mimicking the north facing "under-ledges" that they inhabit in nature.

When Josef Halda was here in 2009, he constructed just such an under-ledge and put in a line of plants. I didn't really hold out much hope; but, 6 out of 8 have survived and the floral display is well worth the effort. The construction is straightforward: any large slab of stone can be supported and counter-weighted on one end enough that a small den can be dug out on the underside. Make the exposure to the north or north east and the plants will be protected from scorch.

Of all the shrubs that can be put in a rock garden, Daphnes are at the top of everyone’s list. It helps to have the image of the nymph who escaped the lust-filled Apollo by turning into the laurel - now Daphne laureola. But plants must have more than mystique; gardeners are practical, earthy types, and their plants must perform. Two of my favorites are Daphne velenovskyi and Daphne arbuscula, and the derivative hybrids and cultivars.

Of the smaller Daphnes, D. velenovskyi is one of the best to grow. First described by Josef Halda in 1981, it grows on stony limestone soils covered with grasses and scattered Pinus mugo in the Pirin Mountains of Bulgaria, where the slopes are warm and dry. In the garden, I have found that it will tolerate both full, direct sun and less sun on a north facing, lightly shaded slope. The main caveat is that it sits high and receives benefit of air movement. Not as slow-growing as D. petraea, it sends forth a thick tangle of thin branches – the wood has a beautiful mahogany tone which compliments the pale, glaucous leaves. The flower buds emerge in late April, darkly colored red; and, burst out into a mass of bloom that enshrouds the whole surface. Flower color is basically pink, though it will vary in intensity. There is a white form that Jurasek found, but I have never seen it here. The fragrance is intense, and will draw the attention of the early insects and humanoids. It also, like many Daphnes, will rebloom in the autumn – for us it will bloom in November and the hard frost doesn’t damage the flowers. Best of all, it is one of the easiest Daphnes for anyone to grow. It transplants very well. However, D. velenovskyi does not thrive on tufa. It may grow in stony soil, but is not as saxatile as one might expect.

Daphne arbuscula, endemic to the limestone cliffs of the Muran River valley in Slovakia is comfortable on tufa. We grow 4 forms of it that Josef Halda collected many years ago. The best attribute of D. arbuscula is its ability to withstand extreme cold and retain its dark green color - as dark as any yew. Growing on those cold cliffs in the Muranskya, without any snow cover, it is often exposed to -30 C or worse. Flowers are lavender/pink with long corolla tubes and are sweetly scented.

Both of these Daphnes are in the same group as D. cneorum, which are commonly grown in the nursery trade as a field grown specimen, pushed with fertilizer, potted into a container and quickly moved to a garden centre. The failure rate is high ~30% and a source of irritation for the gardener and the retailer. Container growing them would help, but they would never have the “full” appearance that the garden centers want. So, you won’t find many Daphnes offered in the regular trade, but they are far more growable than industry folk-lore would have you believe.

Especially delightful and of easier culture are the hybrids developed in the last 20 years. D. petraea and its selections are quite beautiful, but very slow to grow. The hybrids of D. petraea maintain a compact habit, but are quicker to establish. In particular, D. x hendersonii (D. cneorum x D. petraea) has produced several good cultivars, some from Robin White’s Blackthorn Nursery. Leaves are typically small, glossy and dark green. Cultivars to look for are ‘Ernst Hauser’, ‘Aymon Correvon’, ‘Appleblossom’, ‘Kath Dryden’, and ‘Rosebud’. Cultivar ‘Ernst Hauser’ is larger than the others. Flower colour varies from shell pink ‘Ernst Hauser’ to the purplish red of ‘Rosebud’. D. x whiteorum is another cushion shrublet based on crosses of D. petraea and D. jasminea. Cultivar ‘Beauworth’ looks more like D. petraea with reddish pink flowers of good size and dark green leaves. D. x ‘Kilmeston’, a reverse cross of the same parents is more like D. jasminea with the grayish leaves and purple tint to the whole plant that cold weather imparts. Given a warm site, it blooms prolifically over an extended period.

Rick Lupp has produced 2 new hybrids that he felt were worth naming – in this case after his 2 granddaughters. D. x ‘Kelsey Ann’, a cross of D. velenovskyi and D. petraea ‘Grandiflora’, is a small, densely branched shrublet that will follow the contour of a rock or spill over the edge of a trough. Leaves are ovate like D. velenovskyi, but smaller. The blooms are pink and white with a heavy fragrance. D. ‘Maisey Larae’ is the offspring of the Caucasian D. circassica and D. arbuscula. More dome-shaped, it has narrow leaves and the darker colored flowers of D. circassica – with fragrance of course. According to Rick, it is still small enough for a trough.

Daphne ‘Leila Haines’, although it is an older selection, has such vivid coloration (dark red/purple) that it always attracts attention. Described by Halda as a hybrid of D. striata and D. cneorum, and by others as merely a variation of D. cneorum, it is a lovely and distinctive plant whatever its origin may be. The overall habit resembles D. cneorum with a dense mat of spreading branches thickly cloaked with narrow, dark green leaves. This effectively sets off the rich red color of the flowers – and it is intensely fragrant.

Lastly, D. x ‘Lawrence Crocker’ is what could be called the “everyman’s daphne” as it is of such easy culture. A moderate-sized dome develops quickly – with its dense root system it transplants easily. With these 2 qualities being recognized by the horticultural industry, it is rapidly turning up on wholesale lists. It also is a reliable bloomer that will present a good display of flowers through the seasons until winter comes.

If you look at the 2 most recent monographs on the genus, one by Robin White and a more detailed treatment by Josef Halda, you will wonder why more of these wonderful plants are unavailable. Commerce is more concerned with mass marketability. As a result, internet based commerce is helping to open the market.

The biggest pleasure of the past season was watching the new plantings of Chinese gentians growing in the garden. Gentians are slow to develop. G. acaulis takes 3 or 4 years to form a mat/mound of ~15 cm circumference. At that size, it is a colony of individual plants both competing and helping each other to survive. As the mound expands, the population increases. It adds to the vigour of each individual. Observation: gentians like company.

One can also plant a single gentian within a low growing mat and see a similar enhancement of growth. We use Arenaria spp., Gypsophila aretioides, Raoulia tenuicaulis, Androsace villosa types, etc. for this purpose. Basically, the mat should be non-invasive and with shallow roots. Gentians will have longer, thicker roots. Some will push deep into the soil. The sympodial types such as G. verna will also make numerous shallow roots from the branches as they sprawl out along the surface.  Monopodial types like G. septemfida will send out roots from the crown only. Both types will benefit by having the crown within the mat, which will mediate the scorching sun of summer and the cold wind of winter. Perhaps the whole host of micro-organisms that are associated with the mat are more beneficial also.

Traditional gardening has agricultural roots; i.e., the planting of a single species for some useful, human purpose. Nature, however, is complex and decidedly messy-lot's of different plants growing together in a mix of rivalry and alliance. So, when plants are found to be "difficult", the requirements are not being met.  As a grower I know that it is much easier to grow any plant in situ than in a pot. Small pots are for short term–2 years max. Much of the problem is degradation of organic soil mixes. The garden, on the other hand, including our troughs, is our experimental site where we try to create the best conditions we can. Here we can use real soil and have the advantage of mass as well.  For help in fine-tuning garden conditions, it helps to read the seed collectors field observations. Plants described as growing in "high alpine tundra" implies a plant community growing in seasonally wet conditions in soils that are reasonably fertile.  "Rocky pastures" indicates a drier site; the boulders are more ornament. Plants growing in "fissures on cliff faces" are a wonder. The narrow spaces they inhabit must be filled with soil particles that arrive on the wind-smaller sized silt and clay particles that will stick together. These fine-textured soils absorb and retain water.

Back to our gentians. In a trough garden, G. szechenyi sits nestled in a clay crevice that is well elevated. So two criteria are met: the crown remains dry, and the water and nutrition are there-just deeper down in the soil. Like many of its cousins, it is a  thirsty, hungry plant with an additional need for a dry crown. Sometimes in the heat G. szechenyi will wilt; but a splash of water soon revives it. It's hard to imagine how it can manage to flower in such an opulent, luscious fashion. In nature the crown will sit elevated, while underneath may be a wet, boggy meadow.

Another way to protect the crown is to plant into a mat or low mound on flatter terrain where the availability of moisture in the soil remains high. Mojmir Pavelka (www.pavelkaalpines.cz) has an amazing photo of G. szechenyi growing on a large, old hummock of Androsace tapete  – imagine that! Once again the crown is sitting high and dry, but the roots can range down to the wetter tundra below. In the garden, one can create such hummocks with appropriate mat or mound forming plants.  The choice then becomes what special gem is planted in the hummock. Planting into an established mat minimizes disturbance to the look of the garden. Adding these 2 techniques – clay/crevice planting and mound/mat interplanting, is most useful for trough/container planting or a garden space that is small in size, but otherwise ideal. The methods are really quite simple. It takes only a slight change in approach.

(2011 catalogue)