The dormitory suburbs of London have obliterated countless historic gardens. I still remember with a shudder witnessing the last moments of Stubbers, the house on the London fringe of Essex where the botanist / brewer William Coys, in Queen Elizabeth’s reign, grew the first yuccas, Jerusalem artichokes and ivy-leaved toadflax in England – and much else besides, I expect. Humphry Repton did a Red Book for subsequent owners, the Russells. Napier Russell took me to watch workmen from Havering Council break up the black and white marble floor of the conservatory with sledge hammers, before they leased the park for gravel extraction.

All the more wonderful, therefore, to visit a similar house that survived. Valentines is as marooned as it could be in the centre of Ilford, half a mile from the North Circular Road and surrounded by the sort of villas that seem to reproduce themselves in this country, generation after generation, their genes recklessly blending Tudor with Moorish and cottage with Bauhaus.

Valentines has not only survived a hundred years as a council owned white elephant, used as offices, for refugees, as surgeries and a school, it has kept the garden and a great deal of the park laid out around it from the 17th to the 19th century.

Ten years ago Redbridge council engineered two Millennium Lottery Fund grants, one of £3 million for the garden and another of £2 million for the house. This spring it opened for business as a sort of council-owned stately home. It is exceedingly well done, both the house and the garden, which is a rare example of an early 18th century landscape, complete with a long canal, patte d’oie, two shell grottoes, walled garden, a lake and some remarkable trees.

The curator, Nigel Burch, has found an admirable compromise between the demands of a public park and the aesthetic of a country house. Old box hedges in the walled garden brims with the plants of our time in bold decisive blocks. If future landscapes emerge from the humdrum streets of Ilford Valentines will surely deserve the credit.

I am not, heaven knows, a serial conspiracy theorist, but let’s just suppose that, like the Millennium Bug, this flu pandemic is run by someone’s P.R. department – in this case of the pharmaceutical industry. The papers can’t turn down flu stories. The genius who gave it its rather nasty name should be getting royalties. So far (and I’ve got it) it is not nearly as bad as the common winter kind. Lots of people die of that, remember.

Now I’ve started, I’ll go further. It seems to be taken for granted that we are all scared to death of death. Few of us look forward to it (and they, of course, can be criminalized). 200 of our army have died in Afghanistan to ward off (we are told) a repeat of 50 dying in London.

Don’t let me start on Iraq. I’ll stick to us, and the sterner stuff we used to be made of.

Better still, to your relief I’ll return to gardening.

You don’t need to be a follower of Nigel Lawson or Ian Plimer on the question of climate change to demand a rather more rigorous use of evidence. Gardeners are assumed to be soft in the head. An editorial in this month’s The Garden is typical of the confusion that is served to us as gospel. The headline is ‘Climate change may finish Cottage Gardens’. It then quotes an official from the Met Office saying ‘It is quite possible our gardens will look really different in 20, or certainly 50, years from now.’ It certainly is.

The report then shifts to 70 years hence, ’in 2080’, when ‘if no steps are taken to curb greenhouse gas emission,’ average summer temperatures are ‘likely to rise more than 4° C’. According to Hilary Benn, the heatwave in 2003 saw ‘average daily summer temperatures 2° C above average,’ ’estimated to have caused an extra 35,000 deaths in northern Europe’. Clive Lane, of the Cottage Garden Society, ‘has already seen …… primulas and violets struggling to survive.’ At Rosemoor Chris Bailes is happy to see Tetrapanax payrifera thriving, ‘though Rosemoor is in a frost pocket’. Same here. If more evidence of global warming were needed, the exciting new feature at Newby, well north of York, is an avenue of olive trees. My doubts about this are more aesthetic than meteorological.

We have been lucky, over the past 26 years (since the winter of 1982/83 in fact) to have got away with growing plants traditionally labelled borderline for hardiness. Last winter was too cold for a few. But to extrapolate from gardeners’ experiences to global trends is absurd, and the R.H.S. should know better.

Just home from our woods in North Wales with a glowing sense of achievement. We have left something for posterity: not more trees, but a feature that could be puzzling archeologists centuries from now.

It starts with a pond, mere or tarn (the Welsh llyn seems to make no distinction). A body of water, anyway, some hundred yards by thirty, that I made eight years ago by damming a stream through a new plantation of spruce and pine. This is up in the hills, at 700 feet or so, overlooked only by the heathey ridge of the Rhinogs. There is a forestry road, but no footpaths. As soon as I made it I wanted to swim in it. The bottom is soft, though, and there are snags of old roots to discourage you.

So I planned a wooden jetty with a ladder to get me out into the deep water.

It would look slightly mysterious, as though it was expecting a boat. When I got there last week, though, I suddenly saw a better answer. We had drained the pond to explore the bottom. These hills are full of huge flat stones. We could make a flight of steps up from the depths to the sedgy bank. There is a famous path of steps like this in Cwm Buchan, ten miles north, attributed in legend to the Romans.

What would the Romans have done if they had had a Komatsu? This massive engine, in the right hands, can arrange ton-weights as delicately as pieces of marquetry. Wyn Owen, who owns the surrounding hills and the sheep that mow them, could part two blades of grass with its huge bucket. He spent a morning unearthing slabs, shaking them free of earth by tossing them in the air and catching them. In the afternoon, with the blue water of Cardigan Bay in the background, we placed them to form seven giant steps from the bottom of the pond to the bank.

It will have to fill again from the stream before I can run down them, splash in and swim away. The idea fills me with excitement. I understand the pleasure Richard Long (now at Tate Modern) gets when he leaves his traces on nature.

The giant woodpecker I heard in the trees at the end of the garden turned out to be a BT engineer up a ladder making adjustments to a telegraph pole. It was planted, he told me, in 1945, and still good, apparently, for another ten years or so. He explained how to read the labels that tell you the pole’s age and height, a skill I immediately put into practice on every neighbouring pole. My best find: the one that carries my calls over the moat from the house to the road – dated 1934 (and 26 feet high). It doesn’t say whether it’s pine or Douglas fir.

I hurried back to ask my woodpecker friend if 75 years is an unusual lifespan. ‘Pretty good’, he said. ‘We’ll have to change it soon, but it’s still safe.’ ‘What about the new ones?’ was my next question. ‘Hopeless.’ he said. ‘They don’t season them or pickle them properly any more. They used to age them for two years, then pickle them in creosote. Now they’re just fresh trees given a pressure treatment with wood preserver. I have far more trouble with the new ones.’

I wasn’t surprised. Telegraph poles are not the only timber that comes green, unseasoned, not properly treated and ready to rot. We’ve had to replace a gate post after three years. Does no one believe in the future any more?

The least welcome sound to any gardener? Four syllables: honey fungus. I suspected it the moment I saw the rose that accompanied my working life for 20 years, three feet from my desk, winking its harlequin flowers at me all summer through the window, sicken and, within ten days, die.

It was the so-called climbing form of Rosa mutabilis, the slender Chinese rose that changes colour from orange in bud to deep crimson-pink as the simple wide-open flower, once pollinated, fades and falls. I planted it in the wall-corner to the left of my window, knowing that its slender structure of smooth purple stems would not get out of hand and that its flowers would entertain me for much of the year. I liked its story, too, as Graham Stuart Thomas tells it. It was given by Prince Borromeo, the fortunate gardener of those two romantic islands in Lake Maggiore, Isola Bella and Isola Madre, to Henri Correvon, the Swiss botanist whose Flore Alpine excited me in youth like no other flower book. When you see this plate, one of his friend Philippe Robert’s illustrations, you will see that it lies at the heart of what we call Art Deco. Robert did not paint Rosa mutabilis, alas.

My plant on the wall grew to nine feet, hardly qualifying it as a climber, but beautifully framing the window, invaded from the other side by grape-vines.
The rose is dead and the vines are sick. Wisley confirmed that the root I sent to the pathologist was killed by Armillarea mellea – though its black bark, peeling off to show a layer of white mycelium, was scarcely open to other diagnoses. I remembered then that the Japanese anemones in the bed under the windows had once grown so tall that I peered out through their white flowers and vine-like leaves; then next year had barely reached the sill. That was nearly 20 years ago. Had the malignant fungus been lurking along the base of the wall all this time?

The document that the R.H.S. sends out to victims is full of data but little encouragement. The black bootlaces of honey fungus can travel a metre a year, they say, and reach as far as 30 metres. I look despairingly round at the plants within a 30-metre radius. They include magnolias (susceptible), a cedar (highly susceptible), a number of roses, a quince, a crabapple …….. Do I see wilting shoots, or just imagine them?

‘There is no treatment available’ goes the usual rubric – with a subtext, I always feel, of ‘to mere gardeners like you’. Bray’s Emulsion, the old panacea, has been condemned as unsafe (or at least, by E.C. standards, untested). How many gardeners has it killed or disabled? I think we should know. You can still get creosote, a rough and ready version, but woe betide you if the police sniff it around your plants.

Meanwhile the ancient grape vine on the gable is dying, and the next one along the front of the house is looking poorly. Does some witch-doctor know a spell?

St James’s Park must be on the short list of Britain’s most beautiful landscape gardens. The views in both directions from the bridge over the lake outdo anything that even Blenheim, Stowe or Stourhead have to offer. Buckingham Palace is no beauty, but its bulk framed in willows and nudged by a metasequoia closes one memorable view, while the wildly romantic domes and pinnacles of Whitehall to the east evoke an imperial mirage. Oddly enough the arc of the London Eye behind only adds to the effect: a window from the world of ducks and willows onto an exotic empire.

The park of course has magnificent trees, principally London planes, presumably planted in the last phase of its development in the 1820s when John Nash was in charge, not only of building the palace and the even more palatial Carlton House Terrace, but of the gardens they overlook. Over the past 10 years or so they have been restored (with the advice of the Garden History Society) to a version of their original planting. It comes as a surprise, and a reminder of how (not to beat about the bush) primitive gardening ideas were in those days, and how far we have come in the introduction, choice, breeding and disposition of (particularly) shrubs and perennials. One can too easily overlook all the hard work put in by nurserymen, landscapers and critics that have given modern gardening its unprecedented polish. Infinitely more is known today, infinitely more cultivars are available today, design ideas today take for granted a body of sophisticated taste and knowledge that far outstrips all the experience of the old school. Whether we do it justice is another matter.

The garden planting in St James’s Park, faithful to the taste of the 1820s, is frankly a mess by today’s standards. It consists largely of curvaceous island beds low on the slopes from the Mall down to the lake, in which perennials are mingled with what feels like naive enthusiasm among shrubs that mostly have one season (if that) of beauty.

The ‘one of this, one of that’ school of planting dates back much further than Nash’s time; in 18th century flowerbeds the plants, as varied as possible, were apparently kept well part, with an effect we would find woefully spotty. ‘Apparently’ because this is how they appear on plans, and where is there a realistic painting of an 18th century border? In St James’s Park they are allowed to fill out and cover the ground in the modern manner; what is missing is modern colour discipline – and of course the best new plants.

It is a praiseworthy idea, to show us the park that Nash designed rather than a modern version. But a park is not a museum; it is a pity to confuse the two.

Another wedding in the family to garden for with happy anticipation. This time a September one. There should be no shortage of flowers in late September; it is winding down time, when we accept the tousled look of plants that have finished growing and are bent on child-bearing. What could be more appropriate?

The church at Saling is a hundred yards from the house, through a gothic door in the garden wall. The walled garden will be brimming with pink japanese anemones, pale purple michaelmas daisies and white cosmos, Cambridge blue bog sage (a good earthy name for the graceful Salvia uliginosa) and the equally graceful purple Verbena bonariensis. The roses will be in their second flush; pink Felicia, white Iceberg and pale flesh-coloured Autumn Delight, which at the moment needs support for its abundance.

Red penstemons and deep pink sedums, brown chrysanthemums, the turning leaves of vines and Euphorbia palustris, and the broad dome of the Koelreuteria above the churchyard gate door will be the warm notes. All this will be enriched with salvias, the autumn gardener’s standby. Bright pink S. bethellii will be chest-high by then, and I am anticipating wonderful blues and reds from the cuttings I took at Lochinch last autumn. S. madrensis, tall and yellow, partners tall blue michaelmas daisies, S. calcaliifolia is bright blue and S. ‘Guanajuato’ a shrill rich blue that calls across the garden. Clematis will enamel shrubs on the walls that have done flowering. Hydrangeas will be mellowing to indeterminate colours – and the apple trees will be full of fruit.

A reception in the concentration of flowers in the walled garden is Wedding Plan B. Plan A, for a day with no risk of rain, is to walk down to the Temple of Pisces and party round the Red Sea in the middle of the arboretum. There are no flowers here in autumn, just the mellow colours of late-summer trees, secluded in a glade that shuts out the world of roads and fields. Lucy once played Titania. I think she sees her bridegroom as Oberon.