Perhaps not everyone knows that the grand iron gates in Piccadilly are the entrance not only to the Royal Academy (Sir J Reynolds in bronze, brush poised, makes this pretty clear) but also to the botanists’ Valhalla, the Linnean Society. Valhalla seems appropriate for an institution with a Swedish patron saint.

I was there this week for meetings of the International Dendrology Society in the august Council chamber. On the walls and the staircase hang portraits of every canonized botanist, The Old Lions and many plant collectors, from Linnaeus on – with a particularly colourful one of the late Professor Willy Stearn cheering up the Council chamber. From the windows on one side you look down on the Royal Academy, from the other you survey Whitehall down to Westminster Abbey. It could go to to a mere gardener’s head.

The IDS holds its annual Winter Lecture here. This year it was Tony Kirkham’s turn. His subject: 250 years of Kew Gardens and gardeners, from Princess Augusta and poor Fred, Prince of Wales, down the long avenue of celebrated names: Bute, Banks. Hookers sr and jr, Thistleton-Dyer (Tony’s favourite, though a martinet. He wore a dashing uniform), Dallimore, WJ Bean….and Kirkham. Tony has been capo of the arboretum since 2002, totally immersed and most eloquent about his charges.The progress of Kew from a minor royal garden with a mere 5 acres of arboretum to its 300 acre splendour today makes a good story – especially since half a dozen of the original trees planted in the 1760s are still there, feted as ‘the Old Lions’ and propped and botoxed-up as necessary.

The most wonky, now lying on its side, is the original Pagoda Tree, recently relabelled Styphnolobium japonicum, though Sophora japonica to you and me. What an indignity, handing it a 5-syllable genus at its time of life. What tin ears botanists sometimes have – or in this case the Viennese publication that got in first with a name in 1830. Surely the label should at least acknowledge the name it bore for most of its existence here. There could be an acronym, FKA (formerly known as) or even TYAM (to you and me). The other Old Lions, considerably less mangy than the first, are the oriental plane, the original ginkgo, the huge Zelkova from the Caucasus and the Robinia or False Acacia, named for Jean Robin, director of the Jardin des Plantes in Paris (who presumably got in first).

Princess Augusta might be nonplussed to find some of her old trees growing where they do. Shifting them around has long been a practice at Kew. When the Duke of Argyll, another acquisitive dendrologist, died, his nephew Lord Bute took a gigantic horse-drawn wagon and helped himself (or rather Kew) to the best trees on Argyll’s Richmond estate – including the robinia.

Galanthus mobilia

To the Chelsea Physic Garden on the first of its two Snowdrop Weekends. Nippy at 4’C with a north wind. A marvellous coup de théatre on the way in: snowdrops as mobiles hanging from trees in little balls of moss; snowdrops as a rug round the cold feet of Sir John Soane in marble, and snowdrops in drifts along a newly-created path winding through the trees down by the Embankment.

The CPG keeps getting better – and even apparently bigger, as more little gardens and gardens-within-gardens and different horticultural incidents enliven its space. It’s hard to believe that so much can happen within its four acres, including a considerable arboretum of seriously senior trees. Somehow there always seems to be another unexplored or undeveloped patch to be transformed.

Nothing could be more inspirational for an urban gardener – or any gardener with very limited space. Here is the evidence that you can pack it all in, divide your space again and again, shift the focus from one style or environment to another.

Rockery, economic plantery, perfumery, pond, bog garden, woodland garden, order beds, fernery, Antipodean collection… they merge or contrast (more of the former in winter; the latter in summer) to make a magical garden walk, absorbing hours – even on a nippy January afternoon, when galanthophiles have their moment of glory.

I love snowdrops – but that doesn’t make me a galanthophile. On the long table in the sales tent (same temperature as the garden, minus the wind-chill) patient volunteers with frozen feet were guiding us through the differences between the precious named cultivars. Most people ask about the big ones, largely selections of Galanthus elwesii with taller or shorter flower stalks, bluer or greener or broader leaves, and heaven-knows-what variations of exquisite detail in their flowers – at £25 a plant. I’m afraid I asked the obvious question: what about the undifferentiated species? ‘Yes, we had quite a few, but a French woman took the lot this morning’. They have their heads screwed on, the French.

For all the winter chill, the most eye-catching plant in the garden was, of all things, a rose; a handsome mound, seven feet high and wide, of fresh green with reddish emerging shoots and tender leaves. It carried forty or fifty pale scarlet flowers looking none (or only slightly) the worse for the frost. Rosa mutabilis? I wondered. Then I thought of ours, hunkered down and almost bare. Surely a relation? ‘Rosa odorata’, said a cold-footed volunteer. ‘We used to say Rosa chinensis Bengal Crimson, but we’re not allowed to any more.’

It’s what I do on dark January afternoons; retreat a century and half to the world of frock-coats and crinolines, the world of JC Loudon, John Lindley, Joseph Paxton and William Jackson Hooker, the years when gardening was just finding its scientific feet.

My time-machine is The Gardener’s Magazine. I am deep in the issues of 175 years ago. John Lindley, secretary of the Horticultural Society, has just published his Theory of Horticulture, described by its reviewer as ‘as useful and indispensable to the gardener as the compass is to the mariner’. Lindley began by explaining in plain terms how plants work, in ‘a short guide to the horticultural application of vegetable physiology’. Such a thing, it seems, did not exist; gardening was learnt only by tradition and experience. “If I had met with such a book as this twenty years ago I would not have so many grey hairs in my head now”.

Paxton had just built the Great Stove at Chatsworth, the prototype for the Crystal Palace. Loudon enthuses about what the new Penny Post would contribute to gardening, making the distribution of seeds and cuttings possible as it had never been before. The nobility, and even commonplace millionaires, were investing in more and more ambitious gardens, nurserymen were flourishing and plant hunters ranging further than ever. And yet, in January 1840, the government announced it was closing down the royal gardens at Kew. All the plants were offered to the Horticultural Society – at a price. The Society declined; they were offered gratis to anyone who would take them away. And the greenhouses were to be demolished.

Strange, I think, that Paxton’s boss, the 6th Duke of Devonshire, with his house at Chiswick, just between Kew and the Horticultural Society’s Chiswick garden, didn’t put two and two together. The job of saving Kew was achieved largely by John Lindley and his friends, lobbying the Prime Minister, Lord Melbourne. His friend William Jackson Hooker became the first director of the new establishment.

I close my magazine and pick up the newspaper. What do I read? Kew’s budget has been cut again. The world’s most important botanical garden is to be cut down to size. They have already laid off fifty scientists. They may have to be closed to the public out of season. And London is to have a new public garden – on a windswept bridge, of all places, crossing the Thames from the Temple to the South Bank. At a cost of £175 million. Putting two and two together still seems to be too difficult.

How much more room for progress is there in photographing gardens? Books like The English Country House Garden, out at Christmas, by George Plumptre with photographs by Marcus Harpur, seem to have perfected the dream scenario of consummate skill and taste in design and execution – first in gardening, then in photography. They create a never-never land of perfect flowers, perfect viewpoints on perfect designs in perfect weather. Rough winds come nowhere near.

Harpur is the inheritor of a strong tradition, son of Jerry Harpur, whose books encompass for more than the usual round of English gardens. He may have been the first to show us great gardens from all over the world. I once bumped into him in a lakeside garden high in the Andes.

His unglamorous roots were in Essex, following in turn in the steps of Harry Smith, whose garden picture library was the first resource of magazine editors in the 1960s and ’70s. In due course the archive was taken over by Anthony Huxley and Dick Robinson, the photographer who gave his own garden at Hyde Hall to the RHS.

Hyde Hall was a horse whose mouth needed careful scrutiny. The Robinsons’ garden was a triumph of hope over experience, an isolated hillock in the driest part of England, windswept, with no proper access, its views featureless except for pylons. It is unrecognisable today, after decades of RHS investment, but it was a bold move to take a stake in a part of England as unlike leafy Surrey as could be. Essex was not without its garden history: Ellen Wilmott of Warley Place, Beth Chatto at Elmstead Market, Audley End, the Gibberd Garden, Rivers nursery, Pemberton’s roses…. and dreams – the role of photography.

Where does garden photography go next? Technical perfection is in the bag. We would laugh, today, at the grimy images of only thirty years ago. Beyond the purely descriptive, perhaps? The Garden Museum is putting on a show of pictures by Rachel Warne called Faded Glory. proving the visual strength of neglected or abandoned gardens. (My favourite of all the photographs in my own book, The Principles of Gardening, was the opening page; Kenneth Scowen’s shot of an abandoned Edwardian Garden fountain in winter, overgrown (but just to the right degree) with long grass and thistles and old man’s beard.)

But the museum director, Christopher Woodward, has form when it comes to ruins. His own book, In Ruins (Chatto 2001), is a masterly evocation of what they say to us. Far more, perhaps, than straight edges and weedless borders. ‘When we contemplate ruins’, says Woodward, ‘we contemplate our own future’

I was surprised by my own excitement in the garden this morning. I’ve discovered over the years that it isn’t only plants that notice the days being a couple of minutes longer. It stirs human blood, too. Especially on a day of brilliant blue sky.

But the excitement came from a sudden rush of memory of all the things I’ve planted in the last year and shall enjoy in the coming one. Bulbs, of course, but mostly plants that have just ticked over as they are taking root and will really make their entrance in the months to come.

The previous year’s planting (our first) was quick to make a difference. My screening trellis on the end wall is a tangle of solanum, clematis, rose, jasmine and eccremocarpus. There is a big spring job waiting for me here, mostly in taming the marvellous white solanum. I have even warned people myself that this plant is a colonizer. 18 months in the ground here, in an almost undiggable corner under the sycamore, has given it a wingspan of something like 30 feet in our garden and our neighbour’s. Just now I noticed that a stray tentacle is still flowering (it’s freezing hard) in a potted standard of another solanaceous thing, Ipomea (or Acnistus) australe. Few shrubs have the honour of a pot here, but the blue bells of Ipomea have seduced me. (There is a shrub 12 feet across in the Chelsea Physick Garden).

The plants that haven’t yet really performed are a couple of climbing roses and the viticella clematises I look to to colour our trellises late in summer. It always seems a pity to do as the books say and chop them down just as they get a good purchase among the other climbers. One of the clematis (the potentially sumptuous C alba luxurians) and two roses have everything to prove. I discovered them totally suppressed, in a sort of coma, overwhelmed with ivy and hydrangeas.

One rose, fed and watered for a year now, still hasn’t flowered (though its reddish leaves look familiar). Of course the longer it takes the keener I am to know what it is and decide which way to point my thumb. Another one only took a few months to declare itself – and Iceberg can never be unwelcome.

There is anticipation all around: small brainwaves that haven’t yet crested. I planted a Daily Telegraph collection of three pulmonarias; they should be quick to show their colours (white and blue). Last year’s discovery, Salvia vitifolia, is snug under a compost duvet (for as long as I can keep the local cats away). A fox visits our unguarded front garden. If one scrambles over the trellis into the back one I shall not be happy. Nor can I understand why we tolerate these disgusting animals in cities at all.

I hung silver balls in our big front magnolia for Christmas. I see no reason to take them down before the velvet buds open and surround them with purple petals.

The last of the fallen leaves have gone in the bin. I spent this morning cutting down, raking and brushing up, tying in, shifting pots into winter quarters and generally battening down for winter. By lunchtime I could hardly recognise the place: plain surfaces where clutter had been accumulating all autumn.

Who said ‘A plain place near the eye gives it a kind of liberty it loves?’ Repton, I was going to say – only this time it was the less-quoted William Shenstone. In any case it’s true: the foreground of a view, or the part of the garden you first step into, should be open, tidy, free from obstructions.

But what does ‘should’ mean? Says Shenstone? Are there really any first principles of garden design – or for that matter any design – that determine its success or failure from the start?

I suspect most people would put tidiness high on the list. Or ‘order’, to give it a more lofty name. Palpable regularity is, after all, the basis of the French, Italian, Dutch…. anything but English (or oriental) garden design. Order for its own sake, though, can be less than satisfying: trite, even. Your mind (or mine, at least) looks for something more: an agenda. The easiest gardens to design are those with a clear function in mind. An orchard, a potager, an arboretum or a herb garden…anything with a recognisable label gives the design a starting point, a raison d’être beyond the mere decorating of space.

And here, in a little London yard? Perhaps I’m lucky not to have too much space to decorate. I might define this as an outdoor room for growing plants. Whatever I call it, it certainly looks better when it’s tidy.

Bean went live yesterday. Or to put it more precisely the online version of Bean’s Trees and Shrubs Hardy in the British Isles became available on your computer. Botanists, and especially dendrologists, have been saying simply ‘Bean’ for precisely 100 years; since William Jackson Bean (was he ‘Bill’ to his friends?) brought out his book with its eight-word title.

As Head of the Arboretum at Kew (and hence Tony Kirkham’s predecessor) he was well placed to list and describe his subjects, in a judicious blend of botany and sylvicultural experience. By the 1970s his work was in its 8th edition, expanded from two volumes to five as new trees were discovered or invented, botanists wrangled, cultural knowledge piled up and noteworthy specimens multiplied. It became clear that in the digital age no one was going to revise such an encyclopaedia in the time-honoured way involving mountains of paper in correspondence and proofs. If the work was to survive and be revisable it must be online.

The original publisher was John Murray (whose other authors included Austen, Byron, Conan Doyle, Charles Darwin and Sir Walter Scott). Sadly the Murray family sold the firm (still at its original home, 50 Albemarle Street) to Hodder Headline, which is now a subsidiary of Hachette – though still run by its founder, Tim Hely-Hutchinson). Tim H-H is also my publisher. I asked him if he saw any prospect of reviving Bean, and got the answer I expected.

Would he then, I asked, consider giving the rights to The International Dendrology Society (the I.D.S.) as a charitable body which could and would put the work online pro bono publico, and hopefully in due course keep it revised and up to date.

The answer was yes. Two years of concentrated work later the result is on your desk. I’m not going to roll the credits here, but two of the stars are John Grimshaw (whose guiding hand is visible in the lack of blunders in my own Trees) and Bill Hemsley, whose ingenious digits enable me to revise my Pocket Wine Book every year with no paper at all. Trees, by the way, to give it a shameless plug, is reprinted and back in the shops for Christmas. Please don’t compare it with Bean.

I have some generous readers. Just how generous I discovered a few years ago when I said that if anyone wanted to give me a Christmas present I would like a donation towards saving the gardens at Crarae. The National Trust for Scotland promptly received, among many others, an anonymous gift of well over £100,000. The target of £1,5 million was reached well before the April deadline.

For Christmas this year I’d like a donation to The Garden Museum. It is on the last lap of fund-raising for its essential and exciting development plan, which will establish Britain’s first garden design and manuscript archive at Lambeth, where my namesake Tradescant started England’s first museum, his ‘cabinet of curiosities’ – which in due course became the foundation of the Ashmolean Museum in Oxford.

On the initiative of the director, Christopher Woodward, the Ashmolean is lending a chunk of the original Trad collection back to Lambeth. Christopher gamely did a sponsored swim from Oxford to London (eight punishing days in the Thames) to raise funds for it. The appeal is getting a matching Lottery Grant of £3.5 million, but £170,000 more has to be found by January. Please send my present to The Garden Museum.