I’ve given up even trying to make a list of plants I simply must take to our new garden. Too many painful decisions, for a start  – but also the feeling that it’s wrong to hang on. Do I really want to walk round one garden remembering another? If I have discovered that a plant is good, grows well for me, fills a useful role and provides moments of real excitement as it shoots, or buds, or flowers, or when the leaves turn, or even as a winter tuft of hope, I’d like to take it, or a cutting or a wodge in a pot. But not at any price. Nurseries are full of unexplored opportunities.

Thinking about moving, though, has made me remember quite humble commonplace things I rely on and would miss. I was thinking about my favourite campanula, the peach-leaved C. persicifolia: what an easy loyal friend it is, self-seeding generously and then, unlike plants that go to ground, hide for the winter and only remind you they’re there in spring, outfacing the frosts with a neat evergreen rosette of leaves from which, suddenly and vigorously, its summer spire shoots up. Then what wild-flower beauty it achieves with its clear porcelain bells, either white or a pale bluebell blue. Just imagining it, on a dire February day, gives me goose-pimples of anticipation.

There are flowers I forget between seasons. The snowflake is one; you may think it just a snowdrop with pretensions, but when it rises among and above them (as it does by the logshed path) with its leaves not grey-blue but bright summer green, not bashful like the snowdrops but almost brazenly open for business, it feels more like a visiting stranger than the streamside native it is.

Only six weeks to go before we move house. There’s a lot of memories and emotion tied up in a garden of more than forty years. I planted most of the now-mature trees; our children grew up here and our grandchildren (three of them at least), will have it registered in their early memories. But no violins, I insist. The trees will grow on, and our successor has already shared some excellent ideas with us. We can only feel positive, and look forward to our next billet.

There is a contrast. From 12 acres to something like 1000 square feet is down-sizing (or ‘free-upping’ ) as one friend called it. We are moving to a Victorian house in Kensington with a garden that (for the moment at least) stresses the paving element, so competition for space is intense.

I started mentally listing the plants we absolutely must take with us at Christmas. Mid-winter is a good time to start, with so (relatively) little showing above ground. I must try self-discipline: the mid-winter roster alone would fill the whole space, but a white hellebore with inner crimson splashes (H. orientalis guttatus) I’ve been growing from seed has a place. So does Sarcococca hookeriana var. hookeriana – though there’s scarcely room for its name. There’s no room for dogwoods, however vivid their winter bark. A white camellia sasanqua in a tub – maybe. Iris stylosa from under the wall here. Pots of crocus tommasinianus and the everyday snowdrops ……. But where are all the pots going to live?

What’s clear is that we must build a conservatory   – and find room for a greenhouse, however tiny, to back it up. The first priority for glass is our Meyer’s lemon. It has taken nearly twenty years to grow it to six feet in its little lemon-decorated pot, and I have few more precious possessions. Just now the flower-buds are opening and a hint of the coming sweetness is in the air. The other current conservatory star is the Hardenbergia whose light purple panicles droop from roof level. That’s a pot that will have to come too.

How I’d like to be able to claim descent from Jon Johnston. He was a Scottish religious refugeee, born in Poland, who became one of the great natural philosophers of his day – a day in which scholarship was a pan-European affair.

He was born of Calvinist parents, when Shakespeare was writing his tragedies. He went to school in Poland (where he learned Polish, German, Greek, Latin and Hebrew) and university in Scotland.  At St Andrews, in 1623, he studied philosophy, theology and Hebrew, then went back to Poland to teach, before setting off again to Germany, England and the Netherlands to study the closely related subjects of botany and medicine.

When he went back to Poland he became a royal tutor, taking three of his students with him on another tour, this time to Denmark, Norway, England, France, Italy and back to Leyden in the Netherlands, where  his treatise on fevers earned him the title of doctor of medicine. His next journey was to Cambridge and Oxford, then Flanders and Brabant, then Paris, Montpellier and Lyons, then Bologne and Padua.

At the age of 33 he had already visited most of the great universities of Europe. I try to imagine him lugging all his books onto lumbering coaches for another week on the road. He had made his reputation, though. Heidelberg, Leipzig and Leyden all invited him to head their medical faculties. He refused and settled in Sladwicka in the south of Poland, where he spent the rest of his life writing a series of encyclopedias, all in Latin.

I have one of them here, his Dendrographiae sive Historiae Naturalis de Arboribus et Fruticibus, published by a famous publisher and engraver, Mathias Messian, at Frankfurt in 1662.

By strange chance that was the very year that John Evelyn read his Silva, the first English treatise on trees, to the Royal Society in London – the first scientific paper in the Society’s history. Modern tree literature starts here, with two quite different books (Johnson’s a catalogue in Latin, Evelyn’s a series of essays in English) initiating the study of dendrology at the same time.

Why, I wonder, did great minds suddenly converge like this? The science has progressed, through generations of dendrographers adding layer upon layer of experience and knowledge. It has become rather a different business now, with DNA analysis to correct its errors.

But still there is a sense in which I can claim descent from J.J. We both love looking at and listing trees.

” Nothing is a better lesson in the knowledge of plants than to sit down in front of them, and handle them and look them over just as carefully as possible; and in no way can such study be more pleasantly or conveniently carried on than by taking a light seat to the rock-wall and giving plenty of time to each kind of little plant, examining it closely and

asking oneself, and it, why this and why that. Especially if the first glance shows two tufts, one with a better appearance than the other; not to stir from the place until one has found out why and how it is done, and all about it. Of course a friend who has already gone through it all can help on the lesson more quickly, but I doubt whether it is not best to do it all for oneself.”

Take a really good look. Has the case ever been more clearly put?

What is the difference between an artist and an illustrator? There must be one, because practitioners classify themselves in one category or the other. Of course there are artists who couldn’t illustrate (a book, let’s say) to save their lives, and illustrators whose work will never be called art. But in the middle ground there seem to me to be fine artists who are classified as ‘mere’ illustrators, suggesting that their calling is in some way inferior. So what is the difference, and which artist (or illustrator) am I thinking of?

I love the work of Stanley (‘S.R.’) Badmin. He portrayed the English countryside in the 1930s, ’40s and ’50s with a precision and sympathy that made him, in the best sense, popular. In the days of their enlightenment Shell commissioned him to illustrate their marvellous county guides. Many of us learned to see the country through his eyes: particularly the trees. Has anyone understood

and recorded the tracery of winter trees, or placed them in context, with such skill?

Does this make him a great artist? The orthodoxy of today insists that an artist should trouble us, excite our consciousness about something beyond mere appreciation of the physical world, or at least make us aware of that old standby the human condition. Art, as now defined, must induce strong reactions. Any reaction will do, including disgust. Nor does the medium matter: light bulbs are fine; so are turds. Motive, in other words, outweighs competency – by such a margin that mere skill with materials is counted against the protagonist.

There must, therefore, be a new category for people who represent what they observe with skill, care,  even inspiration – but don’t have pretensions to deeper, or less coherent, meaning. Disturbing their viewers  is not their intention. Perhaps illustrators is the term for them. And for great ‘illustrators’, whose work is beyond mere competence, who are excited or inspired to dare to go further and find or create new convergences of ideas? We used to say ‘artists’.

Does this cover it? Illustration stops at a safe point, within our expectations and comprehension. Art finds another dimension expressible only in the meeting of the medium and the subject. When S.R. Badmin drew a tree he gave his pencil his understanding of growth. What David Hockney does is not categorically different.

Who was right: the person who said ‘one picture is worth a thousand words’ or the one who said ‘I prefer the radio: the pictures are better’?

I like books with lots of words in them: page after page of grey matter. Books like the radio rather than the telly. Picture books (I’m thinking of garden picture books) only half-occupy my mind. I am asked to admire one perfect garden scene after another; the captions are rarely enough even to bring me into  real contact with the scene, let alone profound or exploratory. Of course there are

exceptions, when the author has thought through the whole process, using words and pictures together to communicate and explain, but they are rare. What do we call books that are too good for the coffee-table?

I have just put down one of them: Hugh Cavendish’s A Time to

Plant, about the redesign of the über-Victorian garden at Holker Hall in Cumbria. The Cavendishes (Grania is a wonderful photographer) have been working on the design and planting for nearly forty years. Perhaps my sympathy with them relates to the fact that forty-odd years is the time we have spent gardening at Saling.The book is simply the logical outcome: time to explain and invite your reaction. A serious and successful match of words and pictures. Should I see it as a challenge?

There is no light meter more sensitive than a leaf. Barely two weeks since the shortest day, a mere twelve minutes between sunrise and sunset, and there are plants sitting up in their sleeping bags rubbing their eyes. Primroses always seem most alert; their leaves spring to attention as soon as any warmth confirms the change of season. And today, after a frosty night, the air has balm in it and the primroses are opening flowers.

Even if there is proper winter in the forecast a new year with moderate temperatures gives us a head start. Once the aconites have surfaced, the primroses started, the hellebores

pushed up their flower-stalks and the snowdrops their spearheads they won’t go back. Catkins are lengthening all around – most specacularly on Garrya elliptica and the proud pyramid of the Turkish hazel, where the first are already nine inches long.

We were given a new version of Daphne bholua when we went with the I.D.S. to Lake Maggiore three years ago; a form simply labelled ‘d’Aman’ (which is where it comes from). Planted from its tiny pot in the shelter of the big walnut tree on the kitchen lawn it has already reached seven feet, with short branches held close to its trunk – an arborescent look that promises heaven knows what eventual height. It started to flower with the first hellebores. They say you must be gentle with daphnes, and not cut them too enthusiastically. Otherwise we would have a big vase of its ravishing pink flowers in a bower of its shiny green leaves perfuming the house.

Dear Doctor, I have a chronic case of lemna minor in my water garden and wonder if you have a remedy for me. It completely covers the surface of one of the two 12-foot square ponds; the other, under the constant splash of a fountain, is also affected, but less seriously. Why it has infected us now I don’t know. In forty years it has made occasional appearances and I have netted it off, but this time the problem is serious: it has spread through the clumps of Iris kaempferi that occupy three of the corners.

How am I to clean it out? I could try blasting the clumps with a pressure hose – but thatwould send the tiny plants flying everywhere. I could dig the irises out of the water and try to clean them elsewhere before putting them back. No chemical treatment for duckweed, of course, is available or legal  for mere gardeners. And why wouldn’t the pest come straight back next year? I’ve noticed, by the way, that ducks rarely touch the stuff. Nor do moorhens – of which we have an oversupply. Grass carp, I’m told, devour it along with everything else.

An apparent lawn is no substitute for the gleam of water. And I love my floppy irises, some purple, some white, sometimes flowering right up to the first frost. Can you help me, please?