Birders with long lenses congregate on the saltmarshes that run from Lymington to Milford-on-Sea. The Solent way follows the low-lying coast facing Yarmouth in the Isle of Wight. The Yarmouth ferries, looking like black gondolas carrying white Indian temples, criss-cross the water. Cattle wade with egrets and hundreds of geese in the shallow lagoons. In July the sea-fringe was embroidered with a dozen different flowers. The sea is in a trance, the surface is a mirror for the flowers.

Purple sea lavender forms rafts in the shallows between low-and-high-water marks. Its intricate flowers rise above salad-green leaves. Samphire covers the sea-washed flats, and Golden Samphire, bold upright tufts breaking into yellow flowers, the drier higher ground. Yarrow and wild carrot dot it with white, ragwort, tall and bushy, and bristly ox-tongue with yellow, teasel and low-lying rugosa roses with pale purple.

I know this path, and these marshes, in all seasons. In summer the deep channel is crowded with yachts at their moorings. The mystery is the owners of these expensive conveyances who seem never to sail them. They sit all summer, moving only with the tides. In winter there is no colour except in the sky, with lingering sunsets followed by the silver moon-track across the Solent and the red blinking of the lighthouse at the Needles.

In the 1830s Colonel Peter Hawker, a veteran of the Peninsular War, made wild-fowling here an industry, going out with his punt-gun at dawn, he and his man pushing the punt through the mud up to their waists, and recording killing 200 wigeon with a single blast of his blunderbuss. His diaries make good reading, not just about shooting; he invented a new method of teaching the piano, and travelled to Paris to teach. Wigeon? You’d be lucky to see twenty today.

Could anyone calculate the tonnage of new leaves in our parks since it started to rain last week? Summer rain is of one of nature’s greatest luxuries; its first pitter-patter on a warm day one of its most delicious sounds. After a long drought it feels like the all-clear. Emergency over.

After nearly two weeks of daily rain the consolation, as you shake out your umbrella, is that ponds are brimming, streams are burbling, and autumn will be lush and leafy. The blue bags our London borough provides for garden rubbish are already full, waiting for their Wednesday collection. I’ve been snipping the surging shorts as never before, emptying saucers under the pots every day, watching what looks like Jack’s Beanstalk: Verbena bonariensis has overtaken the winter cherry, poking its flowers out through its branches to look down smugly on a mere tree. At midnight in the garden the sounds of rain and the constant splash into our little tank shuts out the world.

The year so far has borne out everything the boffins have predicted about global warming, though the extremes here have been more wet than warm. I feel almost guilty talking to friends in California, where the fire department is demanding firebreaks 200 yards wide – some of them through vineyards, which are relatively incombustible, compared with forest and brush. I fear wine is already being affected by warmer weather – not always for the better. If something is perfect, as great wines can be, how can it be improved?

A week of temperatures over 80 old-fashioned degrees. It’s tempting to stay at home and read. Sun never reaches the terrace by the kitchen door; I hose down the ferns in their pots and sit back in the transat. Do you know the expression? One of those chaises longues on the decks of transatlantique liners (French, First Class).

When I do sally out I plan my course to avoid walking in the sun. There is a sort of science to it, and certainly ground rules. Be back home by eleven, and ten if possible. Avoid streets running north/south for two hours either side of noon, and east/west streets as the sun begins to settle in the west, often its most burning time.

Trees can be your best ally, but don’t rely on them. There will be gaps, and little trees like flowering cherries are not ideal. Planes, limes or horse chestnuts are best. Tall buildings close to the street give the most certain shade (but very tall ones can cause gusty winds). Houses with front gardens stand too far back to be much help, unless their gardens have rather tall trees.

When you turn a corner sum up which side of the new street offers more shade, even if it’s not on your direct route – and be prepared to cross the road as often as necessary to avoid unshaded stretches of pavement.

Key to the whole thing is registering where the sun is in the sky, and where it’s going. (To the right, if you haven’t noticed). Plan your route to have it on your back, rather than in your eyes, as much as possible; too bad if your destination is in the west, or in the early morning, the east.

Where do plants find the extra reserves to react to rain with such glee? And where do they store them? Within hours of a downpour that flooded the streets (and sub-basements across the road that suddenly seemed not such a good idea) there were foot-long extensions on trees. Lammas, the ancient ‘Loaf Mass’ is traditionally the first of August, but Lammas shoots can happen after any good late-summer shower.

They are most obvious on oak, being pale green, or often red. I have not been so aware of them on elms, but was happy to see extensions of a foot or more on the pioneering file of disease-resistant Lutèce elms in front of Kensington Palace – trees that admittedly get preferential treatment from the Royal Park staff, with Kew-style circles of mulch.

I know I’m notorious for looking up when most gardeners look down. It earned me my name of Treedescant. I can’t help wondering, all the same, about so many people’s indifference to trees. People who will coo over the details of a flower ignore the giant vegetable offering them shade. The explanation can be simple: it’s not mine; I didn’t plant it, it’s not my business. It’s true that large numbers of gardeners have room to plant one tree, or none at all. Surely that makes the free gift of every tree in the street, the park, the square all the more precious.

You can collect trees without owning them. It’s been a hobby of mine for decades. After a while you identify and register the vast majority almost subconsciously. I still focus on an oak, say, if it surprises me in some way: size, different-shaped leaves, unhealthy dieback in the crown. And any tree that doesn’t fit a recognisable category demands a second look, even a detour, to find out what it is.

By happy chance our street is a mini-arboretum. I’ve never discovered which enthusiast chose to plant twenty different things instead of the customary avenue of one species. Right to left are: the common street pear, ‘Chanticleer’, two tall double white native cherries, a Caucasian maple, the Japanese Prunus sargentii, Amelanchier ‘Ballerina’, a fastigiate hornbeam (way past its prime), a London plane… and so on for three blocks of intriguing variety. Each contributes something, season by season. How many of the street’s gardeners even know their names? (I haven’t asked).

Am I the only gardener who suffers from the Clean Shirt Syndrome? I go out to the greenhouse in the morning, spot a plant that could do with a bigger pot, spot a suitable empty one (unwashed) and think “I have a few minutes; I’ll do it now”. There’s the bag of compost, I can find some crocks; I tap the plant out to inspect its root and the rootball falls to pieces in my hands. I thought it would be a quick finger-tip job. I’m still holding it as if it could bite; it’s my clean shirt, on this morning. I can’t roll up the sleeves with compost on my hands. I’m stuck; half-committed.

Gardening only works if you get down and dirty, hands in the soil. Every plant knows when you’re in earnest. It can feel your fingers loving it as you lower it into its bed and press the soil round it, gently but firmly, like a blanket round it’s neck before kissing it goodnight. Planting is the great moment of commitment in gardening. You’ve sown the seed or taken the cutting. You’ve done the nurturing, made the decisions. Now you give it its place for life….. from now it’s all hope and expectation. Water is all you can offer it.

Your shirt is still clean? The plant will notice.

I came back to our Hampshire plantation after that mean May wind to find a sorry sight. The gale came at the precise moment when many leaves were in their most vulnerable infancy: just emerging, as tender as nurslings. The wind blew for three days, not far above freezing, and blow-torched the unlucky plants on the point of flushing. The blasts were precise, focussed, rushing up the hill, leaving trees at a lower level merely battered, but searing the growth a few feet higher. One American pin oak, Quercus palustris, was left in full leaf for its bottom ten feet, the upper fifteen feet blasted bare. Of a pair of English oaks flanking the drive by the house one was stripped of two thirds of its young leaves, the other unscathed.

You looked for explanations: what had sheltered one while the other suffered? The corner of a wall, a few pines? The blast was evidently deflected by random insubstantial obstacles, was stronger (or colder) in the middle of the slope than higher or lower, but above all damaged growth that was uncallused and unprepared. As with so many aspects of growth an outcome depends on precise timing. Two related plants may be days apart in leafing, but it can be enough.

The sequel is happier: deluges of rain in June have produced volumes of new growth, long shoots and big leaves. I was talking to a wine-growing friend in California the other day. The mood in the Napa Valley is despairing as they start in their third successive summer of unrelenting drought. Our wine-growers don’t like rainclouds, but would they prefer the opposite?

The garden the painter Cedric Morris made at Benton End in Suffolk was far from being the NGS ideal. ‘Something of interest all year round’ was not his goal. Irises were his passion. His paintings of them (and other flowers too) are explosive celebrations of his love of colour. Among his gardening disciples was Beth Chatto, who propagated several of his favourites. Another friend was Elizabeth David, who took us to meet Cedric and his partner, Lett Haines, one day in the 1970s.

It was a cold day in winter (I remember a savoury brown stew and ample red wine). In the walled garden there was little to see. In the middle stood a lonely shrub that was evidently suckering about with abandon. I asked. ‘Shepherdia argentea’, he said. ‘Won’t you have a piece?’ So that’s my Morris souvenir, now the centrepiece of the tiny seaside garden we care for on the Solent. Its ambitions are not limited to the ten-foot square brick-walled bed in the centre. It puts up wayward shoots anywhere, rising to five feet or so, covered in curving oval silver-coated leaves two inches long, around a much-branched central shoot – trunk is too strong a word. There are six or seven distinct suckers already the same height, filling the bed, above the box and rosemary, campanulas, geums, geraniums, cistus and mint making a seaside tangle. As I write two wrens have chosen it as their momentary perch.

It doesn’t stop, there, though. It has found chinks in the paving round the bed and would eventually make a silvery thicket of the whole garden. Anyone with a sand-dune to fix would welcome it. I have only once seen it flower; little yellow flowers like an eleagnus that are followed, but not here, by the red berries that give it its native American name of Buffalo berry. It needs a mate to fruit. I’m not surprised you rarely see it offered in nurseries; what gardener wants an aggressive suckerer? So the sucker when Morris gave me the piece fifty years ago was me. I have offered it to the Garden Museum for their Cedric Morris celebrations, but now they have Benton End itself, thanks to a most munificent patron, they will inherit plenty.

Perhaps nine months doesn’t sound long in the life of a forest (that is the period between our last visit in August last year and our reunion last week). But through autumn and winter and a glorious spring there has been time for change, and a prodigious amount of growth, now reaching its climax. Luckily for us the lateness of spring gave us the perfect, greenest and most fragrant homecoming. The springtime woods have a score of sweet smells, some as potent as cut and growing grass, some quiet background scents you scarcely pick up until you identify them. Hawthorn and cow parsley are stridently sweet, bluebells and the tender leaves of larches form a quieter background harmony.

There are a few fallen trees, as always in a forest, and part of an ancient wall of huge stones has crumbled, undermined by an ash tree that is now dying. Once you focus on it, ash disease is everywhere, visible in bare twigs or skeletons of a whole tree canopy. Nothing can be done. The forester’s policy is to fell trees that could do damage in collapsing, as most of them eventually will; otherwise to leave them and let the growth of other trees take the light they no longer occupy. Birch and rowan, willow and hazel are always ready to cover the ground. Oaks we already cherish; seedlings of forest trees, spruce and larch, beech and hemlock and pine are clamouring to take over. It has been a wet spring until the past week and new growth is a glorious jumble of all the shades of green.

I related last year how one idiot forester, sent out to kill the notorious Rhododendron ponticum, managed instead to cut and poison our treasured blue rhododendron, R augustinii, the most distinctive plant in the forest. I went out to where it grew, clambering up through bracken and brambles, expecting to find nothing but the blue stain of glyphosate. To my joy I found, scattered around the dead stump, a dozen tiny plants with their little shiny leaves, springing where mere twigs had landed on wet ground and layered themselves. I planted the replacement plant I had brought ten yards away in propitious brown earth.