Agapanthus 'Northern Star' . More purple than blue in this photo, but a glorious colour.

To Kew to see how the mammoth new herbaceous borders are coming on. When they were inaugurated in April, after a year or so of preparation, they still looked enigmatic.. Three months has been enough to turn promise into spectacular performance: surely one of the horticultural wonders of the world. The two borders together total over 2,000 feet of planting; I heard someone mention 30,000 plants. The scale of the project and its ambition, to make an immense tapestry of interwoven plants, of well-considered colours, without hesitation, deviation or repetition, is almost Victorian. Follow the planting schemes carefully and you can see how conditions change with the influence of the other plants around. At the Palm House end there are big trees closing in; the choice of plants tends towards the woodland. It will be fascinating to see how the components knit together and form new patterns of colour. What a job taking care of it will be for some lucky gardeners.

The sight of the Broad Walk disappearing into the distance, thronged with families and lined on both sides with splendid planting, makes me think of the Great Exhibition, the Crystal Palace and the confident achievements of Victoria and Albert. For sideshow there is The Hive, the new pavilion promoting the work of bees in fertilizing (among other things) 80% 0f our food plants. The Hive is a rather beautiful structure formed of aluminium struts, suggesting the complexity of a beehive – and buzzing and throbbing with the amplified sounds of the bees in Kew’s actual beehive nearby.

In the first really warm days of summer, after more than generous rainfall, Kew was looking wonderful. It is Lime Time (Tilia Time to botanists) when the air is sweetly dense with scent from millions of flowers decking some of the biggest trees.

It’s pretty good in the garden at home, too – all 900 square feet of it. The warmth has brought plants into full flower that have been looking tentative, in some cases for weeks. It has pressed the release button on reluctant roses. Salvias and agapanthus are loving it. I am always on the lookout for blue flowers. I home in on them in every garden I visit and in every nursery. There is a (short) book to be written about their allure – and relative rarity. Salvias and agapanthus provide some of the best. Each summer I keep my fingers crossed for Salvia patens to reemerge, and this year I was delighted to see S. vitifolia (big furry vine-shaped leaves and caerulean flowers) had survived the wet winter. We came back from France with a new agapanthus acquaintance: the positively sapphire Northern Star which a friend had planted in big pots, repeated forty times around the terrace of their 18th century hunting lodge, each, with the sun behind it, a gleaming gem. We modern gardeners don’t know how spoilt we are; our ancestors had nothing like this.

Can there be a greater satisfaction in gardening – or in life itself, for that matter – than seeing your careful plans coming to fruition? It is ten years since we sold our place in La France Profonde. Veteran readers of Trad may remember my probably obsessive accounts of tree-planting, building and garden-making in the wide open spaces of the Bourbonnais, the northernmost part of the Auvergne. Bocage (as in Normandy) is the term for the repetition of field and copse and wood and hedgerow that makes such soothing and satisfying prospects.

The vast green rug of the Forêt de Troncais, 25,000 acres of tall oaks, the best destined for wine barrels, dominates the region. Our little farm lies in its pastoral fringes. Charolais cattle, bulky and pale, are the main signs of life around the red-roofed farms.

Our successors have kept everything going as we planned it – even our ancient Land Rover. We bumped around the familiar tracks, looking up at trees I remember as little saplings. Pines we planted in 1994 have had their first thinning and now look like grown-up forest. Oaks that seemed so reluctant to grow at first (and needed expensive protection from the deer) are now an impenetrable green wall, house-high. Better still our successors keep the network of rides open and mown for their horses; perspectives that were lines on the ground are now gloriously three-dimensional; the shape we gave the landscape in our imaginations is a reality of masses and spaces, shapes and textures, with a logic that reveals itself as you move.

In the only spot where the gritty acid soil is deep enough, with enough moisture, I planted half an acre of American oaks and maples to fire up in autumn. Sugar maple and swamp, scarlet and willow oak are trees I could only dream about at home. Here in acid soil and a continental climate (it was 35′ C when we were there) they far outgrow the native species.

And the parterre we squeezed in an awkward sloping trapezoid space between house and barn has acquired authority; you can’t imagine the enclosure filled in any other way than with its beds of box, its walls of hornbeam, troughs of hydrangeas and a froth of blue and white flowers. Only the vineyard has gone, to make a paddock. They were right: the wine was never going to be great.

All summer long

I wish I had kept count of the number of plants that were considered exotic, or treated as tender, when I started gardening, and are now seen as mainstream. I remember, for example, planting my first agapanthus. It must have been about 1972. I waited until June, dug a hole in the sunniest and driest spot, buried crocs and gravel, and tenderly tucked them in. “Headbourne Hybrids” were supposedly the only strain with a good chance. In October I covered them with slates on bricks to keep off the winter rains. They are still flowering, as far as I know, forty five years later.

Is it acclimatisation, breeding, know-how or climate change? Possibly all these things. London, of course has been practically sub-tropical for years now. Remember how we once marvelled at the old olive tree in the Chelsea Physic garden? Now blue and white agapanthus (‘Blue Storm’and ‘White Storm’) line a wall in this Kensington garden, shaded for most of the day, and flower well, if not lavishly. The trick, I find, is to be generous with water and a high-potash feed in spring and summer. Our best plant is ‘Northern Star’; tight-filling the same large pot for five years; it has six tall stems on the point of flowering. I keep its saucer half-full all the time. This year’s new treat is a variety called “Queen Mum” I bought from Hoyland Nurseries from Yorkshire at the Chelsea Flower Show. The flowers on long stems are white, but each petal starts off blue; more of a specimen for a pot, I think, than a border.

Trachelospermum jasminoides (‘Star Jasmine’) was thought doubtfully hardy until quite recently. Now smart London is full of it, and last year we discovered Jasminum polyanthum, which doesn’t seem even to have an English name yet, has moved convincingly outdoors. Fuchsias in the open no longer surprise us. London-centric I may be, but how many things have you found can dispense with customary winter protection?

Shellwork at Ballymaloe

Would you like a grotto? Do you warm to the idea of a cool shell-lined cave, water dripping from stalactites, mysterious reflections in a dark pool? They’re back in fashion. I went to what must be the most beautiful grotto of modern times at the Ballymaloe Cooking School near Cork, a crustacean mosaic, a pristine masterpiece of a summerhouse (no water, admittedly) that perfectly expressed the spirit of what? Grotteity? Grottiness?

Last year’s winner of the PJ Redouté Prize for the best garden book* in French is a tombstone of a volume on grottoes, illustrating a score of magnificent creations, some glistening bright, some spooky, all cool retreats from the sunlit world. It classifies them as, for example, Primordial, Diluvian, Labyrinthine, Sacred, Tellurique, Profane, Underworldly – and the Introductory chapter is called Ouvrir L’Ombre – opening the shade.

As it happens, we have a grotto of our own, deep in the Welsh woods; a rocky tunnel a hundred yards long that set out to be a goldmine but drew a blank. Its mouth, protected by an iron gate, is a gloomy hole overhung by ferns and issuing a dark and gleaming stream. Penetrate the depths (take a torch) and you are in a world of black, dripping rock, with here and there a little cascade to cool your collar.

The grotto spirit, though, can be expressed in less ambitious ways. I have been looking round this tiny garden for a corner to transform into an alcove plastered with shells, with perhaps a pretty dribble into a basin. For now we just have a tank with a Mr Spit like a Green Man and four goldfish; two tiddlers and two gorgeous ‘comets’ with wide waving tails called Halley and Haley (Bopp).

*The book is ‘L’Imaginaire des Grottes dans les Jardins Européens’by Herve Brunon and Monique Mosser. Oh yes; moss. Another essential.

A busy evening after an Ascot downpour (the Queen Anne Cup, I believe: I stayed at home) emptying brimming saucers and relocating snails. Where do they live, waiting for Ascot week? There were fifteen in one corner enjoying the shelter of the agapanthus. Total score for the evening: twenty seven. And why do they climb? I’ve found senior snails climbing down from ten feet or so on a wall. Do they want a better view?

The slugs have meanwhile climbed a newly-planted Clematis wilsonii (a treasure from Hergest Croft) and munched its top shoots before disappearing – presumably to destroy the little Eccremocarpus scaber I planted to keep it company. How this unobtrusive climber came to be called ‘Glory Flower’ I can’t imagine. Its little red and yellow bells on the flimsiest rigging deserve ‘charming’, but certainly don’t compare with Morning Glory. The strain I have (or had) has modest pale creamy-yellow flowers, all the more welcome for unexpected cameo appearances among more socially confident blooms.

I tend to think Chilean plants should be rainproof, but E. scaber likes it dry. So does the marvellous Abutilon vitifolium (American name: Flowering Maple!). Its tissue-weight petals, rather on the hollyhock model, in either lavender or pure white, look as though a shower would destroy them, yet I have seen them in rain forest growing with luxuriant Eucryphia and Weinmannia as dense as redwoods.

A wet Ascot makes a good growing season. Just-planted specimens can grow on without check; established ones, even big trees whose hydrology you would think had settled into a pattern a century ago, can react with a surge of lusty shoots the very next day. You think a tree or shrub (or indeed a perennial) has done its spring thing. Then another downpour and away it goes again, the new wood barely able to support the new new wood.

You can see the effect of rain on growth rates, but what about temperature? It has gone down to below 10 degrees C, ‘growing temperature’, several nights recently – and not got much above all day. Clearly the average temperature is enough to keep things going, but I’m sure when there were two days of sunshine I saw them put on a spurt. I’d love to understand the sensitive mechanism that tells cells what to do.

There’ll be a lot of hacking back to do to keep the paths open this summer.

Tom Stewart Smith models a hard hat

It was hard hat night last week at the Garden Museum. Hard hats with flowers, of course, Ascot-style. It was an evening for supporters of this ambitious conversion – the medieval church of St Mary’s, Lambeth, to museum and school of garden history, art, design and botany (a word described by the director as unfashionable. Really?) to see how the building work is coming on.

The museum and all its works are centred on the fact that John Tradescant the elder lived and died at Lambeth, that this was his parish church, and that just nearby he initiated England’s first museum. His term was his Ark, his Cabinet of Curiosities. Curiosity was on a roll in the first Queen Elizabeth’s reign. There was the New World to explore, better ships and seaways. … and since the Reformation relief from the sense that the church had the answer to everything. Almost anything was a Curiosity, from a monarch’s cradle to a dragon’s scale. London was agog; there were queues to see the Ark. Tradescant’s son John kept up the collection and in due course disposed of the contents to the acquisitive Elias Ashmole, whose name is still familiar from the Ashmolean Museum. When the new museum opens Oxford will lend back to Lambeth exhibits that were first seen by Tradescant fans 400 years ago.

New buildings are going up around the ancient churchyard to house the teaching room, kitchen (a vital and much-appreciated asset) and the archives. Britain’s first archive of garden design and designers, their plans, photographs and memories, is taking shape here around its oldest gardening treasures. Work on the Chancel also revealed a big brick vault containing the lead coffins of four 16th Century archbishops who of course lived next door, as Justin Welby does. Sadly (as it seems to me) a high brick wall separates St Mary’s and its churchyard from the palace and its nine acres of gardens.

It is all being done with £3.7 million from the Heritage Lottery Fund and a similar sum from donations. To round the whole thing off a few more are needed. Urgently, of course.

Mrs Bird, dressed for Manchuria, courtesy of Wikipedia

Who was Isabella Bird? Her name kept cropping up when I asked a Japanese friend questions about history; it seemed that Mrs B was a prime authority. Then I learned. She was a Victorian traveller – and what a traveller. She went, alone, to the limits of the visitable world – and beyond, particularly in Japan.

This was in 1878, when the country had only been open to foreigners for 25 years, and was very far from being modernised. In the north, which she explored with patient thoroughness, there were essentially no roads. She searched for rideable horses (even the best were broken-down nags) and hacked with her native manservant/interpreter from village to village, recording every detail. Lodgings were local inns, devoid of any privacy or comfort. She was mobbed as the first foreigner (let alone foreign woman) ever sighted. Fleas and mosquitoes were everywhere. Often there was only beans and rice, sometimes an egg, to eat. Tracks were often streambeds – it rained incessantly – and she was constantly coming off her stumbling mount. But her prose never falters, and at times becomes poetry. She spends a week examining the great Shogun shrines at Nikko, detailing every carving in its overwhelming decoration. She identifies plants with a keen botanical eye, she describes the Shinto rites: a whole expedition could not have done more.

When she reaches the land of the ‘Hairy’ Ainos, the indigenous tribe conquered by the Japanese, she shows total fascination with the ‘savages’, as she calls them. She finds them physically far more attractive than the ‘puny’ Japanese, and I suspect falls half in love with a young warrior. She spends weeks recording their language, moving from coast to mountains, to compare dialects. And it is clear they fall for her.

This Edinburgh housewife (her married name was Bishop) was not often at home. Her accounts were written on letters to her sister (there were 44 from Japan, thousands of words in each). How she handled pens, ink and paper on horseback through floods is a wonder in itself. But Japan was just one trip. She explored the USA, by steamboat to Cincinnati and St Louis, then the Great Lakes to Canada. She reports on each emerging city in detail, recounts appalling voyages on the stormy lakes and the paddle-steamer passage down the St Lawrence, shooting rapids where one in eight ships came to grief.

Where else did she go? To Malaya, China, Korea, Persia, Tibet and Australia – each one a volume. Since I found Mrs Bishop on my Kindle, she takes every bus ride with me. TfL has competition.

A terrible photo of Ashwood Nurseries' Hepeticas

Whether the world of horticulture is holding its breath or not, Trad deliberates long and hard about his Annual Chelsea Award. Here is his rather breathless report. Last year was easy: Dan Pearson ran away with it for his inspired extract from the gardens at Chatsworth. This year? None of the Show Gardens really stood out. (It was disappointing to see the old Rock Garden Bank largely given over to mere commerce.)

It was the Big Top that held the real treasures – the usual suspects all on top form – with the display of hepaticas from Ashwood Nurseries rightly awarded the top gong. (My sole pot of them has never flowered at all.) – Outside it was a tussle between Cleve West’s Exmoor Garden on the corner site of the title sponsor M&G and Andy Sturgeon’s more portentous geological garden for the Daily Telegraph. Cleve West’s was more sympathetic and believable. Both (and many others) seemed to spend so much space – and presumably money – on stonework that the plants risked becoming mere infill. There were lovely quiet wildling colours in many of them, rather than displays of high horticulture.

A potential challenger for the Trad Award was the Winton Beauty of Mathematics garden, precise, beautifully engineered but a tad too highbrow for this simple brain. My second favourite last year was the Occitane Garden by James Basson. This year was a bit of a repeat, but was so much a corner of Provence (admittedly one with a lavender field) that ‘garden’ was stretching the definition too far. It was beautiful. It represented the dusty backwoods of everyone’s favourite part of France with exceptional accuracy. But horticulture had been left behind.