A Look Back To Three Items About Which I Wrote Earlier This Year
by Art Drysdale
by Art Drysdale


Art Drysdale, a life-long resident of Toronto and a horticulturist well known all across Canada, is now a resident of Parksville, British Columbia on Vancouver Island, just north of Nanaimo. He has reno-vated an old home and has a new garden there. His radio gardening vignettes are heard in south-western Ontario over radio station Easy 101 FM out of Tillsonburg at 2 PM weekdays.

Art also has his own website at

December 28, 2014

The clematis depicted on the stamps comprise (above, upper row, left to right) Samaritan Jo, a stunning multi-coloured flowering plant; Giselle, a beautiful multi-flowering clematis with six-pointed dusky purple/pink sepals; and Chelsea a very compact plant with French Grey rounded flowers which was launched at the 2013 Chelsea Flower Show to celebrate the show’s 100th anniversary. Lower row, also left to right: Anna Louise a free flowering plant with large violet purple flowers which has been featured on gold medal exhibits at Chelsea many times in the past; Countess of Wessex, a delightful white flower which was launched at the 2012 Flower Show by HRH The Countess of Wessex and admired by Her Majesty The Queen on Raymond Evison's clematis exhibit. Completing the set is Clematis Edda, a compact plant which is to be launched at the 2014 RHS Chelsea Flower Show. Below: Raymond Evison in his 2002 Chelsea Flower Show exhibit being interviewed by the U.K. press. Author photo.



It seems to have become customary for me to browse through what I’ve written for the past year, and present excerpts in the final weeks of this year along with the first week of the New Year.

So, herewith is part of my January 19th article this year when I was writing about my U.K. friend Ray Evison, the Clematis King!

“The Guernsey Post Office has announced the release of a special stamp issue which celebrates the achievements of Raymond Evison OBE, VMH, a world-renowned authority, breeder and grower of clematis cultivars, who this year (2013) was awarded his 25th Gold medal at the RHS Chelsea Flower Show (stamp issue date 13 November 2013).

“Guernsey Post’s 25 Years of Gold issue features five of the clematis that Raymond Evison exhibited at the highly successful 2013 RHS Chelsea Flower Show. In total he exhibited 50 different varieties at the show, all of which were raised in his famous Guernsey nursery, something rarely done - if at all - by any other exhibitor.

“Born to a gardening family in 1944, Raymond Evison’s horticultural career began at the age of 15 at Treasures of Tenbury Ltd in Shropshire, England; just eight years later he became managing director. During his time there he developed the garden centre, two small museums and a restaurant – whilst attracting 20,000 visitors annually to visit John Treasure’s famous Burford House Gardens. Drawn by its climate, Raymond moved Clematis production to the island of Guernsey in 1985. A brutal winter had killed a third of his mother stock and he moved to the sunny Channel Islands near France where he set up The Guernsey Clematis Nursery to take advantage of the milder climate and the plethora of empty glasshouses where Guernsey tomatoes once grew. “The Guernsey Clematis Nursery Ltd. has proved to be a hugely successful venture, as the nursery produces up to a quarter of the world’s annual requirement of young clematis plants. Raymond, who moved to Guernsey in 1987, has bred and developed more than 100 clematis cultivars and has probably introduced more than anyone else worldwide.

“Owner and Managing Director of both his companies, The Guernsey Clematis Nursery Ltd and Raymond J. Evison Ltd, Raymond Evison O.B.E. is a nurseryman and breeder, horticultural exhibitor, horticultural judge, acclaimed lecturer, author and photographer. He is the author of numerous articles on plants, gardening and the genus clematis published in books and leading magazines in Europe and North America; his horticultural photographs are used widely in publications.

“Raymond Evison has more than 40 years of experience growing and introducing new clematis to the world's gardeners. One of his greatest loves is to search worldwide for plants either in the wild or in cultivation and he has been responsible for introducing many new Clematis into cultivation for the world's gardening market. He holds an NCCPG (National Council for the Conservation of Plants and Gardens) Collection of Clematis of over 500 species and cultivars.

“The nursery now produces five million young plants per year and exports to 20 countries worldwide.

“Raymond Evison said: “I am delighted that Guernsey Post has produced this very special set of postage stamps. It is an honour to be celebrated in this way and I am grateful for the huge team effort from our nurseries.”

“Dawn Gallienne, head of philatelic at Guernsey Post, said: “Over the years Raymond has enjoyed huge successes at The RHS Chelsea Flower Show and this year he celebrated his 11th consecutive gold medal. We are thrilled to be able to showcase just some of the beautiful clematis which drew the crowds at Chelsea, including three which made their debut at this year’s show – and we’re particularly delighted that Raymond has photographed the stunning images which are depicted on our stamps.”

* * *

Just two weeks later this year I wrote about some research work funded by the Royal Horticultural Society having to do with the cooling effect of climbers trained on building walls. Here is that piece.

According to Matthew Appleby writing in the on-line January 24 edition of the U.K. Horticultural Trades Association (HTA) journal, “wall shrubs and climbers can provide ‘significant passive cooling’ with wall temperatures behind the plant canopies up to ten degrees C cooler, HTA research has found.

“Experiments by HTA-funded PhD student Jane Taylor, led by University of Sheffield senior lecturer in landscape management, Ross Cameron, used a replicated wall system outdoors. It showed that during warm weather, walls screened with evergreen cherry laurel (Prunus laurocerasus) were ten degrees C cooler than the surface of bare walls.

“Air next to the walls was three degrees C cooler than nearby bare walls. On clear sunny days, walls screened by plants were significantly cooler between 11 am and 6 pm, with the greatest differences in mid-to-late afternoon. Ross Cameron said species such as jasmine, honeysuckle and fuchsia may be better ‘cooling’ plants than ivy because their leaves are more effective at cooling the surrounding air.

“‘This is probably good news for the industry because the implication is that many of our highly ornamental and attractive flowering climbers are likely to have positive functional benefits to the wall too,’ he suggested.

“Taylor said the research adds weight to the argument that plants could be used to reduce buildings' energy loads by partially substituting for artificial, mechanized air cooling. Brick was chosen as the building material to help demonstrate the potential of plants to provide summer cooling and winter insulation to older domestic housing stock, where retrofitting by other means can be difficult.

“The research also emphasized that not all ‘green infrastructure’ should be treated in a generic manner by policymakers and practitioners. A range of controlled-environment studies showed that different plant species have different capacities to cool wall surfaces, and the mechanism by which cooling occurred could vary between plant species.

“Cooling due to the presence of fuchsia, for example, was strongly reliant on evapotranspiration, whereas ivy (Hedera), honeysuckle (Lonicera) and jasmine (Jasminum) cooled primarily through shading. Prunus cooled via both shade and evapotranspiration.

“Although not normally considered a wall plant due to its short stature, lamb's ear (Stachys byzantina) was included in the study to assess the effects of hairy, silver leaves. This species was surprisingly effective at cooling with mechanisms being attributed to shade, evapotranspiration and an albedo effect--the silver leaves reflecting back light from the wall environment.

“Another important factor in optimizing the cooling effect was the thickness of the foliage. Developing a uniform facade of full transpiring leaves may be more promising than developing a thick, deep canopy of foliage where the leaves self-shade each other.

“Green facades lend themselves well for domestic properties. Little previous research documented cooling advantages in a temperate climate.

“PhD student Jane Taylor's thesis also showed very strong positive effects of green walls' plants on providing insulation to walls in winter.”

Perhaps as we all strive to save money on the ever-increasing costs to heat our homes (and offices) it might be worthwhile if landscape architects in particular took the results of this project to heart!

* * *

Finally this week here’s an item on the banning of insecticides and certain good plants in the European Community that appeared in the March 9th article here.

As spring approaches (yes it actually is!) negative comments are beginning to be spread by the usual suspects. For example, the anti-everything people are once again emerging from between the baseboard and floor denouncing all chemicals for virtually all purposes.

Additionally, the group of insecticides known as Neonicotinoids which are invaluable in both agriculture and horticulture are often coated on seed in agricultural uses, and the seed is buried in the ground. Thus it is inaccessible to bees. But the loud unknowledgeable complainers continue to blame Neonicotinoid insecticides for bee colony collapse disorder.

Studies in Europe and in North America where Neonicotinoid Insecticides were applied consecutively for ten years have reported no accumulation and no bio-accumulation. In addition the class of Neonicotinoid insecticides has extremely low toxicity to humans, extremely low toxicity to other mammals as well as birds and fish.

Then there are those who are back on their band bicycles (somewhat like bandwagons) decrying the use of 2,4-D and Roundup for weed control—oh yes they too are back. They fight the use of these terrific chemicals even though Health Canada (the ultimate arbiter) state that they are perfectly safe used according to label directions. And, they fight on even though there is now a significant listing of jurisdictions where previous bans have been modified, or totally withdrawn.

I intend to report further on these two topics in coming weeks, but for this week, let me focus on yet another group who think they have legitimate complaints, having to do with plants. I refer specifically here to the Coastal Invasive Species Committee (which is one of 17 regional weed control committees in B.C.), but there are ever so many other such groups who believe they are doing good works in trying to eliminate certain “invasive species” in other parts of the country.

For example, in Ontario the Norway maple (Acer platanoides) is considered by several groups as an invasive species. And yet, from the point of view of being successful in dense urban conditions it is far superior to the much larger, native sugar maple (Acer saccharum).

Just this week I came across mention of four lists (categories) that the local Coastal Invasive Species Committee have. The four categories are: Prevent, Eradicate, Contain and Control. The Prevent category is composed mainly of species known to occur in limited distribution and low density. The committee advises to eradicate if found. The infamous Kudzu vine (Pueraria montana), a prohibited weed in B.C., is on this list and it is possible it could grow here as it is known to grow in Leamington, Ontario.

The second category Eradicate are known to occur in limited distribution and low density here and the same instruction applies: Eradicate if found. Included in this category are giant hogweed (Heracleum manteg-azzianum), Jimsonweed/Devil's apple (Datura stramonium) and milk thistle (Silybum marianum). Some of these are not only prohibited weeds in B.C. but fairly major nuisances.

However, milk thistle has been used for over 2,000 years medicinally for diseases of the liver and gallbladder. Coincidentally on one of my visits to the Sissinghurst garden in England (with a group in tow), one of the participants told me that she took this regularly and swore by what it did for her.

The third category, Contain, consists of species that have established infestations in portions of the region. They recommend containing existing infestations and preventing spread to un-infested areas. Included in this category are yellow Archangel (Lamiastrum galiobdolon) and yellow flag iris (Iris pseudacorus).

The final category (considered the worst by the committee) is Control, about which they say: “established infestations common and widespread throughout the Coastal ISC region. Focus control in high value conservation areas. Use biological control, if available, on a landscape scale.” Included in this group are common tansy (Tanacetum vulgare), English holly (Ilex aquifolium), English ivy (Hedera helix), periwinkle spp. (Vinca), purple loosestrife (Lythrum salicaria), Scotch broom (Cytisus scoparius) and St. John's wort (Hypericum perforatum).

It is appalling to me to see so many good plants that we grow in our garden (Lamiastrum, Iris pseudocorus, Ilex aquifolium, Hedera helix, Vinca, Lythrum, Cytisus and Hypericum) all listed as no-no’s! We easily keep them in bounds here and I for one do not think any group should be trying to keep them out of gardeners’ gardens.

It seems that I am not the only one who disagrees with the “ban it” thinkers!

In the European Union there has been much discussion on compiling a list of plants to be banned, period. And, if it happens there how far behind can we be?

According to Matthew Appleby in the Friday, February 28th edition of the trade magazine Hort-Week, Britain’s Royal Horticultural Society has expressed a major concern.

“The RHS has expressed its concern during a House of Commons Environment Audit Committee meeting into invasive non-native species, about proposed EU regulation that would give the authorities the power to enter properties to destroy or eradicate invasive non-native plants deemed to be of concern to the EU.

“The new regulation, which will be voted on by the European Parliament in April, will effectively ban species of plants deemed to be of ‘Union Concern’ from being brought into the EU; reproduced (for instance, set seed in the case of plants); transported within the EU, or even possessed.

“This ban on possession goes far beyond the existing regulation on invasive non-native species in England, although this power already exists in Scotland. The Scottish Wildlife and Natural Environment Act grants powers to enter properties to destroy suspect plants, although there is no ban on possession.

“A cap of 50 organisms on the list of species of Union Concern was part of the original proposal, but this was rejected by most EU member states, leaving it currently unclear how many species will be subject to the ban, or the process for including species on the list.

“The RHS said: "While the RHS welcomes sensible and proportionate steps to prevent the spread of invasive non-native species it believes this new regulation is too rigid, especially in its stipulation that a species listed as invasive in one EU country would be ‘banned’ in all countries, regardless of whether or not it posed a threat.

“‘The RHS is keen to see any EU Regulation recognize regional differences to avoid ornamental plants which pose no threat in the UK, being banned because they are considered a problem in other EU countries.”


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