Revelling in a touch of drought

A SPRING drought brings two particular pleasures. The first (which I may come to rue, a fool in his paradise) is to wander the acre with the garden hose at evening, sending a glitter of golden spray across the seedling vegetables and catching the sun descend behind the islands like a fat, ripe tomato.

The earth is warm and smells delicious. The water is free, from the stream, and was already on its way down the hill: I can use as much as I like, This could, of course, be the year the bog empties its last trickle from the hollow under the ridge and the stream finally dwindles and dies.

The second pleasure, sensibly enjoyed at noon in a straw hat with a sharp edged. Italian shadow, is to hue weeds from their moorings. knowing the work isn't wasted, that they will not root themselves again in the next shower, while my back is turned.

The herb garden, a new folly, greeted the spring with an up rush of annual weeds, seeds stirred up in shaping and raking the beds. Somewhere among them were the tiny shoots of plants installed last autumn. There is a sixth sense that tells the gardener with a hue, in mid stroke, which little plant he wants and which be doesn't. I seem to have filed away the profiles of mouse ear, charlock, dead nettle, shepherd's purse, bitter cress and the rest, and just know, from the smallest tips of leaves, which is the cherishable mullein or lovage.

Some weeds are too much of a gift to destroy. Fumitory is welcome equally among the herbs or in the lettuce bed, in its wreaths of lacy foliage and pink, waxy bells. There's a long and typically confused folk history to the plant which, in the Middle Ages, was fumus terrae, "earth smoke". One modern dictionary of plant names claims that its root smells "remarkably like the fumes of nitric acid" but, having sniffed hard at a good number, nothing reminds me of the choking brown smoke in that dreadful lab at school.

A similar libel crops up in another group of "weeds".

wildflowers, really - that I always spare if I can. Herb Robert is known, says Richard Mabey's new Flora Britannica, "as much for the acrid, mousy stench of its leaves as for its perky pink flowers". Well, I have just pulled a big handful of its ferny leaves from the ditch and crushed them under my nose, and no mousy stench do I get: a rhubarby tang from the red stems, perhaps, rather like well, Herb Robert and thus a memory from somewhere, unpindownable.

This plant is one of the Geraniaceae, which are the true wild geranium family, the cranesbills (from the shape of their seed cases). There's another - cut leaved cranesbill - which I leave along the ditch, and a third kind - soft cranesbill that makes mats of round, frilly leaves along the edge of the path.

It was the random pleasure of these wild Geraniaceae that led me on to realise what "flowers" would thrive best in my garden. So now I have half a dozen varieties of cultivated cranesbills, with big, brilliant blossoms, making weed suppressing mounds and seeding themselves everywhere. On the same principle, the acre's primroses have been joined by spring hosts of polyanthus, and its thistles by stately blue globe thistles, and tall candelabras of teazles, which butterflies love.

Plants on the borderline between wild and cultivated can suddenly spring up everywhere if they happen to like the habitat. Some years ago, when I wrote about a rare - even, possibly, extinct Irish wildflower, the sea stock, Matthiola sinuata, a reader sent me some plants of the closely similar Dame's violet, Hesperis matronalis, taken home to her garden from a cliff top near the Giant's Causeway (not a good idea).

Dame's violet (sometimes "sweet rocket") was probably brought out of France by the flower loving Huguenots in the late 1500s, and it escaped into the English and Irish countrysides by way of cottage gardens. It's a tall, robust plant with spikes of white and pale purple flowers, and a sweet, spicy perfume quite as powerful as stock or wallflower. From the one original clump, it has set up a dozen more beside paths all over the garden: a hugely successful and welcome "weed" that blossoms for months on end.

I could also, if I wanted to, pull it all up inside an hour (but as a Huguenot from way back, certainly will not). Out along the roadsides of the west, however, another garden escape is springing up in thickets with a sinister, unsuppressible, vigour.

JAPANESE knotweed, Fallopia japonica, is officially regarded as the most pernicious weed in Britain: it is actually illegal to plant it there in the wild. It was introduced from Japan as an ornamental shrub in the early 1800s, was first noticed in the wild in London in 1900, and by the early 1960s its colonies stretched across the island from Cornwall to the Hebrides.

By midsummer and on into autumn, the big, heart shaped leaves and lacy white spires of knotweed blossom are carried six feet high or more on hollow canes jointed like bamboo: an elegant sight, perhaps, in a Big House garden, but alien and a bit slithery against a dry stone wall in Connemara. The thickets are dense and monopolise the ground, and the smallest fragment of root will get one started.

Is it just the run of good summers that has given knotweed its head - or is it also, as I suspect, the steady disappearance of donkeys and cattle from the "long acre" beside the road? Livestock love to browse the plant, given the chance: so do people, apparently, when they have lived with it for a while. In America, where knotweed has spread from Newfoundland to Missouri, the tips of the shoots, at exactly the asparagus like stage they're at now, are steamed for a sorrel sharp vegetable, or pureed for a cold spring soup.