This is the time of year when they have to send out a search party for me as the light fades and it’s time to decant the claret.

It’s the time of overload anyway, when too much is happening at once. What is a coherent reaction when nineteen plants are calling out to be admired and ground elder is flowering lustily in their midst? This year there is confusion to add to surfeit. Why is

the banksian rose in full flower at the end of May instead of April? Has Magnolia soulangeana finished flowering or not? And why not? Camassias overtook bluebells, weigelas overtook azaleas, ashes are still bare and hawthorns are still opening an unprecedented froth all through the hedges.

This is when I realize how over-full the garden is, how tall the trees are and how jam-packed. An arboretum has become a forest while my back was turned – except that it wasn’t: I’ve been staring at it in ecstatic indecision spring after spring, thinking how lucky I am.

Rhododendron augustinii

To Bowood on a rainy day to visit the Rhododendron Walks, open for the first time this year. It is almost incredible that England still has such wonders under wraps, but the Lansdownes have kept this separate part of the gardens, miles across the estate from their celebrated Capability Brown lake and spectacular water gardens, as a private enclave around the Robert Adam family mausoleum.

Why miles away? Like many rhododendron collections it relies on greensand, ridges of which crop up on high ground, principally in Kent and Sussex but also in a line between Poole harbour and the Wash. At St Clere in Kent, for example, the Pinetum perches remotely and incongruously on top of the North Downs; beech hangers below, conifers and rhododendrons on top.

At Bowood the woodland garden is sheltered and framed by oaks, and some of the most venerable beeches I have ever seen, on a series of steep spring fed slopes that offer everything rhododendrons could need: shelter, moisture and air-drainage.

Some of the first collections from the Himalayas were planted here in the days of Sir Joseph Hooker, by the great great grandfather of the present marquess. Subsequent Lansdownes have added to what is now a woodland garden of extraordinary beauty, while the present marquess, the eighth, is a full-time hands-on gardener. I am no rhododendron expert, and easily impressed by a bush thirty feet high covered in huge pale pink flowers giving off sweet scents. When I am told that it is one of the earliest hardy hybrids with Himalayan blood, and that its name is lost in time, I can only nod in assent. It is clear why such creations became the show-flowers of the great, raised and selected with as much care as their race-horses.

Satiety would soon be reached, though, if they were too densely planted. It is the beauty of Bowood that there is space and variety, that glades and rides, pools of bluebells and grass open to the sky make it a magic wood rather than a rhododendron forest, There is the delicacy of white dogwoods, the brilliance of Pieris, one the size of a cottage, and above all, here and there among the rich green and the pale glades, floating over the bluebells, the sumptuous near blues and purples of Rhododendron augustinii.

If I were to have one rhododendron it would be this native of Sichuan, the nearest flowers to blue produced by its tribe. In fact it is the only species I have planted in our North Welsh woods. (R. ponticum needs no planting). Ten years or so ago I planted a dozen plants around a waterfall and along a stream under beech and larch. Accidents happen in a forest; sheep the most frequent. Eight of my augustiniis survive, now ten feet high, their feet in bluebells. Why didn’t I plant fifty?

The rain at Bowood, at least in retrospect, was like the creative touch of a great director. The shine and drip (it didn’t pour), the grey light and the cool soft air completed the magic and made the exotic (even the ultra-exotic) seem believable.

Bluebells at Bowood

Plain simple degrees, and lots of them, are what the garden needs this miserable May. Fahrenheit or Celsius; it won’t mind.

The plants are in as much of a muddle as I am, not so much early or late as all over the place and not going anywhere. Oak has never been so far before ash, but magnolias are just sitting, their flowers half open, some petals frosted, others effectively drowned. And my favourite winter-flowering cherry has caught that nasty fungus and lost all its leaves.

By early April we had had a mere 140 millimetres of rain in the year. Since then we have had 160. If it was the wettest April it is the coldest May. The only plants that keep on growing in this low temperature are weeds and grass; the mower sinks in to the boggy ground and any step on the border to reach the weeds leaves a foot-shaped puddle.

And yet. When I splashed out this morning in my winter coat to see what could be done I walked into a wall of what to me is the Chelsea smell: azaleas in all their boudoir sweetness. The pale faces of Azalea mollis, soft yellow in the grey light, were gently chiding me: look at us, you grumpy old fool.

A reverie is a comfortable place to be. I have just spent ten, fifteen, I’m not sure how many minutes watching Berberis petals float over a weir: tiny flakes of gold on black water, drifting slowly, with a growing sense of purpose, over the surface of my little rock-rimmed pond.

The weir (the whole thing is tiny: the weir three inches across) acts like a magnet, mysteriously setting the surface in motion. Petals settled in the centre of the pool begin almost imperceptibly to move, gradually, gently organizing themselves to head towards the fall. Little groups of four or five move together, as though some force (could it be surface tension?) held them in formation. Individuals feel the same pull and move at the same speed.

I switch focus and look deeper, through clear water to snail trails (if that’s what they are); paler tracks on the leaf-littered bottom. It has always baffled me how we can switch our vision from reflections to the surface, and through the surface to what lies below, with only a change of thought.

Three feet from the weir the petals change course, reset their sails and pick up speed. They keep in their flotillas, but now there is urgency in their drift, they collide, form bigger squadrons, then coalesce into a pool of gold to hurry through the gap between the rocks. They fall perhaps an inch, perhaps two, but just enough to break the surface into silver glints.

As a way of seeing the whole world it is much more interesting than a grain of sand.

I honestly didn’t plan the look of the garden now. I would never have been so bold or single-minded, or trusted to the impact of a single flower. It is a triumph of the Triumphator. Who named this simple white lily-flowered tulip I don’t know. Perhaps he or she had the same experience. The long files of bulbs I planted three or four years ago down the centre path of the garden have the stage to themselves, shining white, ice-cool on a background of tender greens, sharp green, and the bottle-bank brown/green of box hedges.

Why are there no other colours? Two weeks of constant rain seem to have left most plants perplexed. The Crown Imperials have finished; one or two tentative flowers sprinkle little pink geraniums and a burgeoning perennial honesty. The apple trees are in blossom, but the colour seems washed from their petals: there is no wattage in any colour except green – and the bright lamps of White Triumphator, its pointed petals upright despite the downpours.

If it is true, as Christopher Lloyd feared, that this marvellous bulb is growing degenerate, and that its stock is weakening, it would be a terrible shame. It is seventy years old, I learn – though I still don’t know who coined its strange name. But if this is weakness; three years in the ground and still standing straight after two weeks of rain; triumphator, meaning hero of a Roman ‘triumph’, is right.

When did ‘dilettante’ become a term of abuse? ‘Amateur’ no longer has the status it once had, either. I think the probable reason is that both suggest a life in which not every minute needs to be spent in gainful employment. A leisured class, indeed; ‘posh boys’, even.

Is there a paradox here? Leisure is what we spend most of our lives working for, only, when we achieve it, to have it despised. Meanwhile, the assumption has taken hold that only ‘expert’ opinion is worth listening to. And an expert (disregarding the disrespectful description of ‘a drip under pressure’) means a person employed to know and pronounce, whether properly qualified or not.

For myself, I reclaim the name of dilettante. And even, indeed, amateur. We are people who do things for their inherent interest and the love of it. We offer views we are not technically qualified to hold – or at least not to mention. A dilettante is probably a hedonist, pleasure being his goal.

Is this a moral dilemma, or an aesthetic one – or is it a dilemma at all?

You possess a building which all agree, monotonously, in describing as ‘iconic’. One view of it, from a public road and across a riverside meadow, is as well-known (all right, then, iconic) as any view in the country. The catch is that the reverse view, from the building and its surroundings, is the public road, emphasised by traffic lights and the resulting line of the brake lights of waiting cars.

Is there an obligation on the proprietor to leave the view open, both ways, or would he be justified in planting appropriate trees to screen the road from his own viewpoint?

The building, you may even have guessed, is King’s College chapel in Cambridge. During the summer coach parties of tourists make an inevitable stop to photograph the view.

members of the college learn to accept the traffic across the summer view, softened by leafy trees. In winter it is different. From teatime on there is only one thing you see across the Cam from the college: winking red lights.

There are worse problems, I know. But there is also the hope of a solution, at least in part. The college has just succeeded in ‘respacing’ (which means felling) half the trees between the road and the river. Italian alders planted 40 years ago as a nurse-crop for oaks (this was the plan when we lost all the magnificent elms) have finally gone – in the nick of time: the oaks they were ‘nursing’ were almost shaded to death.

In their place are planted more oaks, lots of hawthorn, and an entirely new feature for the Backs: a crowd of Chinese dogwoods, which will make a mass of white flowers at May Ball time in June, and (I hope) colour up in an orange/harlequin way in October.

Flanking the rather stark and lonely stone Back Gate of the college we are planning to plant a pair of weeping willows: the first step in screening the intrusive traffic lights. In other words, no obvious move; just slow and sensitive improvements.

My visits to the tropics have never been anything but fleeting and my impressions of tropical gardens have never advanced beyond confused admiration. Do our gardening rules, or conventions, or idioms, apply? If not, what distinguishes a garden in the tropics from a glorious hothouse display?

We are just back from the legendary island of Mustique, a speck in the Caribbean where normal rules are suspended; where tropical nature appears entirely benign. We were guests of Felix Dennis at Mandalay, his house derived from a Balinese temple and surrounded by gardens (many acres of them) that magically answer the questions I just asked. Our rules can certainly apply – and tropical colour and vigour can give them extraordinary new validity. The essence, of course, is control, as it is in gardens everywhere – but control of more powerful forces. There are plants that can grow a yard in a night, and leaves that could brain you if they fell on your head.

Mandalay, though, is almost English in its peacefulness, its composure, its slow revelations, enclosure by enclosure, of potent growth masterfully calmed. What is Balinese (swooping gables like mid-ocean waves, gates and screens, intricate carving, and solemn stone figures) speaks a visual language that justifies the cultural gap.

The Caribbean has no such language of its own: shanties and colonial porches are a pretty limited patois. But the devotional symbolism of the East (you can almost hear the chants and gongs) is at least as potent as the Greco-roman idiom of our own classic gardens.

The first gate, with its concave-gabled roof, shows you a downhill curving avenue of palms though a park of short grass mown not by sheep, as you might imagine, but by the tortoises that wander everywhere on the island. Then comes a second gate, flanked by menacing stone warriors and flaming dragons, before the first courtyard, calm, domestic, with two square fountain pools in a carpet of grass. Not grass as we know it, but a deep spongy surface that rears up in random mounds. Enormous conch shells hold water in their white basins on either side of the next gate: the front door of the single-storey house. Fire comes before water; challenge before welcome.

The opening of these great wide doors is a moment of revelation: straight ahead and far below lies the sea, scattered with yachts. But between you and the sea lies a piece of still water reflecting the sky and meeting the sea with an invisible edge. And daily at sixo’clock the sun goes down in purple and gold in the centre of this magic mirror.

Now you are in a cloister of gleaming burnished deep brown wood carved in fantastic intricacy and filled with the colours of flowers and fish. Scarlet and silver koi dart and glide among tall blue water-lilies. Pale blue plumbago covers the banks between purple and scarlet flowers and deep green circular leaves. A gallery at one end of the cloister is open to a view of palms and distant hills. And each room off the polished corridors has a balcony revealing another kind of garden: some intense with bamboo and idols, some serenely open to the world.

There are many layers, cultural and physical, at Mandalay; of formality, for instance, from the central drawing room, frescoed as a derelict stone temple, its roof just waving palms, to studies and bedrooms and playrooms and the swimming pool, an alternative heart to the house. The pool, surrounding an island and surrounded by plants, is filled by one long cascade and spills over another, seemingly into the sea far below. I wish I could name half the plants, but among the bougainvilleas, as varied as azaleas, the hibiscus and gingers and strelitzias, heliconias and anthuriums, the frangipani trees with their white flowers on bare branches scent the night. There are layers of lower storeys too, joined by staircases and galleries among the jostling fronds of palms.

Felix Dennis is an extraordinary Maecenas, publisher, poet and author as well as the gardener who, here and in Warwickshire, orchestrates such creative planting. Even Mandalay pales beside the thousands of acres of native trees he is progressively planting for our general benefit near Stratford on Avon.