People still ask me, ten years after we left our old Essex house, Saling Hall and the garden we made there over forty two years, ‘Don’t you miss it?’

The answer is no, or not really. But why not? In the first place because we are happy in London, with all its amenities (especially its parks), but principally because memory works so well. I can still take mental walks, not just at Saling, but in all the gardens and places I’ve known well and been attached to. In fact it’s what I do when my head hits the pillow. I can visit our woods in Wales, or our daughter’s garden in Hampshire, Wisley, or the garden of a chateau in the Médoc where I had a hand in the design, or stroll as I often do in Kensington Gardens, where trying to match the dogs with their owners is a game I sometimes play.

The other reason our Essex garden remains fresh, and even exciting, in my mind is because our successors there are doing such a good job with it. Not perhaps exactly what I was planning to do, but intelligent, interesting and above all pretty. The walled garden has not looked so good or been so well maintained since our early years there and its complete replanting in the early 1970s, or at least since Christopher Bailes joined us as a very young gardener – en route for his illustrious career at Merrist Wood, the RHS gardens, and eventually Kew.

It was a risk, I admit, hiring a young man whose experience didn’t go much further than leaf-sweeping, but when he sat on a bench with me at Saling, in the walled garden, and said ‘I would just love to garden here’, something told me he’d work hard and do well. After a few weeks, when he asked to borrow my gardening books, I knew for certain. But not that one day he’d be in charge of the orchids at Kew. Now I read his books on orchids, and hollies, and feel quite proprietorial. The RHS has given him its Victoria Medal of Honour. You can’t get more senior than that.

It’s not just the roses that are loving this summer. The pubs are having a field day on their pavement extensions; clear proof of global warming. Ten years ago a pint outside huddled near the door constituted London summer. Now they have built permanent terraces on the pavement and in parking spaces. Do they pay parking charges?

Kensington smells of the “Confederate Jasmine” that has become a signature climber on its garden walls. The name was given to Trachelospermum Jasminoides because it grows south of the Mason Dixon Line, the frontier of the Confederacy in the American Civil War. In this street it lushes out so far from a garden wall that you have to make a detour round it. Its variegated form scrambles over the little balustrades across our garden, while I cut off shoots three feet long.

Warmth is what plants want to speed their growth, even more than water. It’s not just roses that are growing fit to bust. And flowering as we’ve never seen them before. Everything from our lemon tree in its pot to the creeping campanula that has become a London weed is jutting out shoots twice the normal length covered with flowers. Agapanthus is almost arborescent. Two blue-flowering bushes I specially treasure are painting the garden the colour that is rare in summer: Lycianthes (alias Solanum) rantonnettii is tall enough to shade the greenhouse and Acnistus (alias Iochroma) australis dangles its elegant soft-blue bulbs, fit for a painting of fairies.

There is a downside to these exotic excesses: an ugly rash of banana plants dwarfing front gardens with this gross and tatty leaves. Not everything you could grow is beautiful.

What has given roses (and not only roses) such a boost this year? Bushes that routinely put on a respectable show have gone into overdrive with heavy trusses of flowers. Roses are falling from high in our sycamore. I feel like the guests at the feast of Heliogabalus in Alma Tadema’s painting being smothered under cascading flowers. Somehow the seasons, from the heat of Last August, through a kindly winter and soaking March, have engineered the perfect rose-storm. Dead-heading has already filled the Council’s blue bags again and again. Where does the Council compost all this fragrant material? In Kensington the shameful answer is that it doesn’t. It burns it.

I’ve never hesitated about which is my favourite tree. Oaks stand in a class of their own. Their rugged permanence, their cranky growth, their intricate mass of details in crooked shoots, leaves idiosyncratically sculpted, tough little wooden fruit, furrowed grey bark and limbs stretched wide in defiance of gravity all give them a presence no other trees can match.

And after the oak; a second choice? For me it’s the larch, the conifer that sits uneasily in its classification. It’s no softwood; its timber can be hard as horn, element-defying. You can build boats with it. It will grow ramrod-straight to a hundred feet. Its spring leafing is a poem in tender green, its flowering has a Fabergé intricate elegance, its autumn colour glowing yellow. In winter it makes skeletal cathedrals and its seedlings people the forest floor with exquisite soft miniatures.

When larch was introduced to Britain in King Charles the Second’s time it was greeted with rapture as a plant of infinite potential. John Evelyn rhapsodised about it in his Sylva, and the ancestral larches still stand, like wrinkled grandmothers who have never lost their poise, where their godfather, the Duke of Atholl planted them four hundred years ago. He planted millions of them in the first afforestation of Scotland; they remained the leading forestry tree until the great conifers of the American West began to revolutionise forest planting. The news that a new form of phytophthera has started to kill them is deeply unsettling.

The rain gave the procession an authenticity that a day of glittering helmets might have lacked. Or perhaps reminded us of glittering sunshine at a Windsor wedding not long ago that came to grief. The weather had given the Royal gardeners anxious weeks recently. A Spring so uncertain and late makes ceremonial bedding even trickier than usual. The scarlet tulips at Buckingham Palace, calculated to bloom for the Coronation, were so late in opening that I gather the gardeners had pelargoniums ready to take their place at the last minute. Happily, slightly warmer days encouraged the tulips; they shot up to be on parade with the guards on the day.

Coronation Day and the first aphid squish of the year. Roses in bud and greenfly at work. The first roses here are the notionally perpetual Parson’s Pink China and Mad Alf (aka Madame Alfred Carrière) already twenty feet up the sycamore. I can’t reach the buds on Mad Alf to tackle the greenfly but the little china rose droops over a camellia close at hand. It’s pale pink, soft and drooping at the first raindrops; an unpretentious thing, but with a famous history as one of the original progenitors of the roses that keep flowering, when conditions are right, almost year round: hence its alternative name of the Monthly Rose. I don’t really recommend it. It is the present performance of a plant that matters – except to historically-minded romantics like me. Who of course have a field day at coronations.

If you want to be sure to keep any plant you should give it away. It’s the gardener’s reinsurance policy. Give it, of course, to someone with green fingers who can give it, cutting or seed, back if you then lose it.

I reinsured a lovely white-flowering form of Honesty, doling out its seed to anyone who admired it. When it flowered in conjunction with its transparent seed-capsules it lit up its corner. Where is it now?

It’s been a near-perfect planting season – at least for spring planters like me. The heavens have been generous with timely rain; our streams are racing as I have rarely seen them. In the New Forest the ponies are splashing through gleaming puddles that are almost ponds. The first thrilling flush of foliage is filling out while the flowing trees, cherries and crab-apples and especially magnolias, grab all the attention in the landscape.

Aren’t our public bodies too austere in their tree-planting taste? Our planted woods could do with more variety. We don’t lack autumn colours. Oaks alone produce a medley. But I always plant a scattering of Prunus avium, our native cherry, even among conifers. Recently in Wales I have planted a scattering of Norway maples, cheerful with their lime-green flowers in April and reliable bright yellow leaves in late autumn.

Forestry is a deeply conservative art-form. It relies on centuries of experience; anything original is considered dangerously risky when the final reckoning is fifty or a hundred years in the future. You will live with your mistakes for the rest of your life. Gardening of course works in a much shorter timeframe. The safest planting of all is annuals.

It’s a mystery who planted this Kensington street as an arboretum, rather than the conventional avenue. In its four hundred-odd yards we have about fifty different trees, including one I still haven’t been able to name with much assurance. Outside the house we have one of the Council’s favourites, the double-flowered version of our native cherry, Prunus avium Plena; in fact three of them in a row. They must be fifty years old, and as many feet high. Their long branches are supple enough to wave in even faint breezes outside the bedroom window. Flower-buds, now conspicuously knobbly, will soon open to cover the street with a dazzling white cloud.

Across the road a young Prunus sargentii. Sargent’s double pink cherry, brought by the famous director of Boston’s Arnold Arboretum from Japan in 1890, could reach a similar size. Pyrus ‘Chanticleer’ crops up here, as it does almost everywhere in London; a safe but scarcely exciting tree, round here invariably grafted, so it soon sprouts a bush of suckers round its base. Will they never learn? There are several liquidambars, two fastigiate hornbeams, now at their best with catkins and young leaves, a Manna ash across the road and a hawthorn looking very modest among the tall specimens. A solitary plane, on the other hand, looks over-mighty.

Does any conifer make a good street tree? The most prominent planting I can recall is the avenue of Metasequoias along the Cromwell Road extension in Chiswick. If the function of a street tree is to provide shade, they fail. They form a green (in summer) curtain, but a fairly dismal row of sticks in winter. Is there an ideal? They must be in scale with the street; happily this street is double-width – a mini-boulevard, you might say. In wide-enough streets, as an alternative to the magnificent London plane, there is a lot to be said for elms (and very little against them) once we regain confidence in their survival.