Global local gardens.

Green roof with Sedum and Virginia Creeper

We like to think of ourselves as having a global reach, both as garden designers and as horticultural educators, with clients and students located throughout the world. I have long maintained that a well-trained gardener can practice his craft anywhere and is able adapt to local conditions.

I still believe this to be true, but have on occasions been stopped in my tracks by comments from home-grown amateurs or professionals.

I recently contributed to an internet landscape forum discussion about green-roof

Virginia creeper - invasive?

gardening, suggesting a reference book I thought might be useful to an American garden designer, while innocently mentioning our own green roof here in France. We have covered the top of a concrete tool shed with Sedum and it does very well, as does the Virginia creeper, Parthenocissus quinquefolia, which offers a change of leaf scale and gorgeous autumn colour. Insects are pleased with both plants and the combined effect is both attractive and practical. “Virginia creeper”, I was told, “is invasive”.

Turkey Oak -Quercus cerris

I quite fancy myself as a plantsman but here is an aspect of plant selection it would be easy to get wrong; designing a border in a foreign country could get you into hot water, when your favourite flower turns out to be the bête noir of local environmentalists! In the USA the National Invasive Species Council keeps a watchful eye on these things and their web site links to pages dedicated to each State, detailing the noxious weeds which are a problem around the country. There is a Federal List noting those considered noxious throughout the country and in addition each state has its own list.

And what a range of plants! Across the country 106 plants are prescribed in this way, while California lists 242 on its own. The UK has problems with Rhododendron (Rhododendron ponticum), Indian (Himalayan) balsam, (Impatiens glandulifera) and Japanese Knotweed (Fallopia japonica) famously causing difficulties in the wild. The UK organisation Plantlife has a substantial list which, like those in the States, contains some surprising plants including Ailanthus altissima, Quercus cerris and several Cotoneasters.

Here in central France, the river Cher is slowly being clogged up with Water Primrose

Water Primrose on the banks of the Cher

while the Oak woods are taken over by Robinia pseudoacacia originally grown for vineyard support posts. The story does not end with plants. Hornets accidentally imported from China in garden pots are currently finishing off the honey bee population, already under pressure from disease and agricultural pesticides. In the Canal du Berry which follows the river, American signal crayfish are decimating young fish and imported Coypu undermine the banks.  Gardeners and landowners are largely to blame and it would seem we have to be much more circumspect in the choices we make. I have noticed a tendency of many of my American students to select native plants so perhaps the message has got through over there and it is we Europeans who need to learn the lessons.

One country’s weeds are another’s prized specimens. For the record, when I design a garden in another country I either use a local plant expert to assist with plant availability and desirability or research the issues myself using local gardening associations, university horticultural departments, growers and other sources. That way I am less likely to make a fool of myself by suggesting inappropriate plants. It’s not always straightforward, being a globe-trotting landscaper, but I am glad I am still asked to work around the gardening world.

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Green roofs, Buddleja and a trip to the South of France

As the weather gets cooler our garden fruit and vegetables are coming to an end, the kids have gone back to school and the season of mushrooms and nuts has started. A slight detour from our usual morning walk takes us through the wood where the Ceps grow and past a large number of Walnut trees; we have taken to carrying bags with us on our walks.

Mushrooms

A selection of last years wild mushrooms

Thoughts turn to keeping warm over winter: we have just ordered 1000 litres of fuel to top up the tank which suppliers the central heating boiler. The French are very keen on alternative energies and “green” housing solutions are installed in even the most modest property. Heat pumps and solar heating panels are very common in the village and while they produce warmth very cheaply the set-up costs, even with government grants, are enormous for a house of the type that we own. After inviting a number of companies to quote we decided it made little economic sense to install heat pumps but did spend money on insulation, both for the roof when we replaced it and for all the exterior walls. But with ten external doors leaking heat and a couple of dozen ancient single-glazed windows, this is not the most thermally efficient building.

We are installing a clever stove in the lounge however, which burns wood pellets, is cheap and efficient to run, highly controllable and should heat most of the ground floor. We are considering one for the new Garden Design Academy classroom but the log cabin is fantastically cosy and in spite of its size was heated when it was our office in Codicote with just a couple of little electric radiators. It’s an environmentally friendly building as it stands but we plan to top it off with a Green Roof and have started to locate and propagate suitable plants in seed trays of leaf mulch.

Sedum mat for a green roof

The UK is a leader in green roof systems, with much of the research having been undertaken in Sheffield University. France leads the way in green- or living-walls and a recent conference of the World Green Roof Congress in London brought together experts to share ideas and encourage the uptake and implementation of these natural and attractive insulation systems. We already have a garden storage shed covered with Sedum but here in the countryside it will make much less impact than in the cities, where they will reduce thermal emissions and reflected heat from buildings, cut down rainwater run-off and greatly improve local air quality. The living roof for the cabin is therefore more of a conversation piece for visitors and will  help me gain experience for projects we may have in the future.

If you find the idea of a green roof appealing you can easily install one yourself on a garden shed or other building provided the existing structure of the roof is sufficiently strong to support the additional weight. Of course, if more support is needed it can be added. The basic components are protective layers for the roof, drainage material, compost to support the plants and the plants themselves. The details vary depending on the slope of the roof (you can do great things with a flat roof) and the type of plant you wish to grow. Various component systems are now available and I have even seen rolls of appropriate plants offered in UK garden centres, looking much like turf.

www.Livingroofs.org offer a DIY guide which you can download while a book, Planting Green Roofs and Living Walls is one of many published by Timber Press. I’ll let you know how our version develops.

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The autumn is the best time to plant a garden and with our cabin nearing completion we are looking forward to utilising the additional planting opportunities the building creates. In a recent plant brochure I was intrigued to read about a new Buddleja called Blue Chip, the first of a series going under the name Lo and Behold.

Buddleja Blue Chip

I am very fond of Buddleja but they can be very large plants, unsuitable for small gardens. Several breeders have attempted to produce smaller forms including Elizabeth Keep of the East Malling Research Station whose English Butterfly series should be better known. ‘Blue Chip’ (Lo and BeholdTM Series) is a hybrid involving B. davidii, B. davidii var. nanhoensis ‘Nanho Purple’, B. globosa and B. lindleyana created by Dennis Werner of North Carolina State University.

His aim was not only to create a genuinely dwarf buddleja, but also one which doesn’t produce self sown seedlings. In the USA traditional buddlejas are banned in some states because their prolific seedlings are smothering native plants in some habitats and we have all seen Buddleja growing from the sides of church steeples in England.

The Low and Behold series will be available in several colours before long but Blue Chip is a lovely shade of blue, flowers for months and grows no larger than 2 feet tall, making it ideal in a pot or as ground cover. I hope to be growing it soon.

Buddleja lindleyana

Buddleja lindleyana flower

We have the Chinese species B. lindleyana and find it a great plant, with long purple racemes of flower produced over the bush all summer. It was name after John Lindley, English botanist, nurseryman and founder of the flower show in the Chelsea Physic Garden, whose name is also recognised in that of the RHS library. The other species involved in the breeding  of Blue Chip is B. globosa, a huge shrub with balls of yellow flowers (there use to be a lovely plant in the walled garden at Kings Walden) and this has been crossed with B. davidii to produce B. x  weyeriana, which we were given cutting of this year. There are several varieties of the yellow Butterfly Bush B. x  weyeriana and as yet I am unsure as to which we have. Honeycomb is said to be the best, a creamy yellow variety selected in the USA from plants bought in the UK under another name, while Sungold shows some purple in the flower. Golden Glow and Yellow Hallow are other yellow varieties while Orange Glory and Bicolor are warmer colours; all are scented and easy to grow.

We have been studying Buddleias in local gardens to try to find the best white. We think we have spotted it in the grounds of the old people’s home and will be chatting up the staff shortly to beg for cuttings. Buddleias are very easy from cuttings at any time of the year but a thick shoot of this year’s growth will root over winter if suck into the soil in a sheltered place outside. That should provide another plant for our White Garden.

The best white Buddleja in Chabris?

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France is such a large country that when we are asked to look at a client’s garden we try to save them expense by combining visits. Our next trip is like that, with an appointment at a house close to Carcassonne and the Canal de Midi, another between Nice and Antibes and the final call in the Vichy area.  Each garden will have a different soil and climate and each client entirely different requirements and expectations. In addition, two of them speak no English while the third is Dutch (fortunately she speaks English because my Dutch is limited to a few place names pronounced badly!).

Combining business with pleasure, we are also spending a few days relaxing by the Mediterranean to celebrate my 56th birthday and the second anniversary of our move to France. I hope we will visit a few nurseries and gardens in the area of Antibes and if we do I shall report on them when I get back.