Do you control your garden, or does it control you?

Leaving the garden to its own devices leads to many discoveries, but eventually you have to show it who's boss. By Anna Pavord

I sometimes wonder whether I'm driving the garden or whether the garden is driving me. I don't think, by nature, I'm a very bossy person ("Dream on," said our oldest daughter with heavy emphasis when she saw what I'd written) and I like the notion that the garden might have its own ideas about what it should be doing in certain places and seasons.

Its ideas are frequently better than mine. Flowers, by self seeding in places where you would never have dreamed they would survive, tell you a great deal about themselves. But there comes a moment when a patch is out of kilter. You suddenly feel an overpowering urge to take it by the scruff of the neck and sort it out. It has gone too far down the road of self determination.

This has happened with a bit of the garden called the round border, though it isn't round, but egg-shaped. It was originally made to mirror the shape of an old apple tree whose branches spread over it. It was also the site of an even older garbage dump, so that rather than being flat, it was mounded up in the centre. The soil, being full of cinder, drained beautifully. That is a treat here, where heavy, sticky clay is the norm.

Almost as soon as the bed was made and planted up - predominantly with blues and yellows - the apple tree, its centrepiece and raison d'etre died of honey fungus, but by then a 'Bobbie James' rose was rampaging over it. We cleared away some of the outlying twiggy areas of the tree, then left the bulk of it to prop up the rose. Later, the rose died of the same disease and the skeleton tree blew over in a gale.

By the time that little mess had been cleared up, the border looked like a battlefield, but it gave a good excuse to reinforce the rest of the planting: lavender, the narrow-leaved sage 'Hidcote', the dark-leaved lobelia and the tender perennial Felicia pappei. Set out as mere sprigs in the late spring, these spread rapidly to cover about two square feet with dense bright green almost succulent foliage and a long succession of daisy flowers, bright blue with yellow centres.

The biggest things left in the border after the apple and its attendant 'Bobbie James' had collapsed were the shrub rose 'Fruhlingsgold' and a Phlomis chrysophylla. The phlomis, which comes from the Lebanon, is an odd looking thing, with lime-green felted leaves and, in June, whorls of hooded yellow flowers which emerge from the axils of leaf and stem. It is more compact than Phlomis fruticosa, the well known Jerusalem sage, and slightly less hardy. The rose grew in an elegant fountaining way to about seven feet, keeping its stems out of the way of the plants underneath. The flowers were semi-double, creamy gold, richly scented and came in a rush in late May and June with only a half-hearted repeat flowering later on.

You notice I speak of the rose in the past tense. That, too, has suddenly given up the ghost. Honey fungus again, I suspect, which will lurk forever in this border, waiting to attack any shrub that is old or ailing. I don't lie awake at night worrying about it. Honey fungus is like pneumonia. If you are young, healthy and vigorous, you will shake it off. If you are old, frail and already suffering from some other problem, it will shake you off.

Roses are particularly prone to attack. So are apple trees, chamaecyparis, Leyland cypress (hooray), witch hazel, privet, cherries, rhododendrons and weigelas. So those are the things that I won't be planting in the border again. But, having taken the rose out, I realised that while I wasn't looking, a lot of other things had been going on there that shouldn't have been. The phlomis had become too big; so had the grey-leaved teucrium that had looked so fragile and tentative when I first put it in.

They had completely shaded out and killed the folicias that had been such a feature of the border when I first planted it. The agapanthus didn't seem to be flowering as well as they should, either, and the very pretty daylily Homerocallis citrina, with long, narrow scented trumpets of yellow flowers, had given up under the encroaching canopy of the teucrium.

The fact that the grey-leaved shrubs were doing so well was probably due to the excellent drainage - they would rot anywhere else in the garden - but they had suddenly become obnoxious rather than a delight. For ages you go on saying to yourself, "That shrub's doing very well." Then one morning you suddenly realise that in fact it has got above itself. You have to get into the driving seat and put the patch back on course.

But, given that both shrubs are on the tender side, should I take action now, or do the sensible thing and wait until spring, when a harsh winter might have done half the job for me? Although I am itching to get out there and hack away, I think I had better wait. A whole series of mild winters has undoubtedly helped these two get to the overpowering size they are now, but I'd hate to lose them altogether. Cutting back stimulates fresh growth and now is not the time to be encouraging that.

Without the 'Fruhlingsgold' that spread to take over some of the space first occupied by the old apple tree, the border now is without a central focus. I'd like to put in another tree, but it would be suicidal to try an apple or even a crab apple with the honey fungus sitting there insidiously. I read somewhere that wood infected by honey fungus glows in the dark, like the mushrooms we used to see in the Dominican rain forest. I wish I'd known that before. I would have saved the old apple wood and lined it along the path to the wood shed, which is as black as pitch.

If not a crab apple, then probably a thorn. That is what I am thinking about at the moment. Crataegus x lavallei to be precise - small, dense, naturally mop-headed, with glossy leaves, excellent fruit that persists for a long time through winter. It won't do anything to reinforce the blue and the yellow, but it won't get in the way either, as the redness will come at a time when pretty well everything under it has given up for the winter.

That is another reason for wanting a tree that peaks at the low ebb of the year. Laburnum would be spectacular, but I'm not very fond of it and the flowers come when there is plenty else to look at in the border. It would overpower it, too.

I rescued some old bearded iris from the first planting and they enjoy the warm, gritty site. So do the grassy-leaved Iris sibirica, which have smallish flowers just like fleur-de-lys. This is the iris you often see in Dutch flower paintings. 'Heavenly Blue', an old variety, is the best of the ones in my garden. It is supposed to prefer moist soils to dry, but thrives nonetheless. The border gets well mulched in late winter and Iris sibirica seems to like that.

In another part of the garden it grows in semi-shade, though it does not flower quite so freely in those conditions. You do not need to split and replant as frequently as you do with bearded iris. Only when the centre of the clump has died out completely do they need attention. Then you drive a spade into the clump to detach the best growths round the edge and replant them in soil that has been refreshed with bonemeal. They look good with hostas and ligularias.