The killing field

Now's the time to arm yourself to the teeth and commit carnage in the garden. Illustration by Sally Kindberg.

Having arrived in a place that grew little but elder and nettle, I've been obsessed since we've been here with planting, planting, planting. Show me a bare bit of earth and I would ram something in it.

But we've been in our house long enough now for the things we've planted to have done a lot of growing. For a time I persuaded myself that the bank was a romantic jungle. Now I am forced to the far less pleasant conclusion that it's a mess. Something has to go, and if it's not me it has to be them - the plants that have grown too big for their situation or have not delivered what I was hoping for.

So I have been flailing around like Vlad the Impaler, uprooting, burning, creating mayhem. I always supposed I was a pacifist. It's quite frightening to discover this latent ability to deal death and destruction all round.

Usually I find myself apologising to plants I dig up and explaining why they've got to go. Not now. "Look," I said to 'Agnes', the rugosa rose on the bank. "You've had 15 years to get your act together. I was promised big, double, amber-yellow flowers, heavily scented. I was promised bushy, dense, clean foliage. And what have I had? Long, scraggy growths. No flowers. Horrid rust-ridden leaves. Enough already."

Usually, too, I think it must be my fault rather than the plant's if it's not doing well. For years I've had this notion that everything that goes wrong in the garden is down to me. In general, that is better than supposing problems always to be someone's else's fault, but suddenly I am tired of guilt. I've done all I can for this rose: pruned it, mulched it tenderly with the best cow dung that Dorset can provide, kept it free from bindweed. It's been a one-way relationship and I've had enough. It's gone. Burnt. Destroyed.

It's a heady feeling. Now I'm looking far more critically at plants on the bank with the suspicion that space - pure, calm, open, airy space - would be better, in one or two other places, than the existing muddle. It's so dense, that growth on the bank now, so congested, that not enough plants come into the spotlight.

The process started with the ceanothus that we tore out from the front of the bank to make more room for small plants and bulbs. But getting rid of the ceanothus also brought back into prominence the aralia behind it. I had always intended the aralia, a lovely Aralia elata 'Variegata', to be the key plant in this particular patch. The ceanothus (C thyrsiflorus var repens) was supposed to sprawl low in front of it. Instead, it reared up and up and completely dominated everything around it.

The slow-growing aralia couldn't fight back fast enough. In winter, its framework is reduced to its few strange, stubby, upright stems. But the ceanothus was evergreen and grew so fast that when the time came for the aralia's fabulous great pinnate leaves to unfold in April, there was nowhere for them to go. Now it is breathing easy, the 3ft leaves balanced out horizontally like the branches of a cedar.

Making space, taking things out, need not be as wholesale as it has been with the 'Agnes' rose and the ceanothus. Sometimes cutting out branches is enough. Lifting the canopy of trees by taking out one or two of the lowest branches is a surprisingly effective way of gaining more gardening room. This is what I need to do with the evergreen Portuguese laurel under which a big Decaisnea fargesii is growing.

I wouldn't want to be without the laurel entirely. It stands on the boundary between us and our neighbour and provides useful cover. It also shelters our garden from the prevailing south-westerly winds. But it is a dense tree, and the decaisnea tends to lean out from under it and wave its great leaves (pinnate leaves about 3ft long) over the lawn. Then the grass gives up.

If we take out a few of the laurel's lowest branches so that it doesn't sit quite so heavily on the decaisnea's head, the decaisnea itself will feel that it can grow up into the vacuum that has been created, rather than reaching out over the lawn. The laurel branches could have been just cut back, rather than taken away entirely, but I don't think the effect would have been good. The unnatural truncation would have caught your eye and felt uncomfortable.

The decaisnea itself needs cutting back, too. Left to itself it would make a big, multi-stemmed shrub at least 15ft tall and wide. But like many multi-stemmed shrubs (cotoneaster, philadelphus, etc) it can easily be kept at a more manageable size if you regularly take out one or two old stems each year.

I won't do that now. Even in the white heat of my Impaler mode, I recognise that this is too good a shrub to risk losing. Pruning always kicks a plant into top gear. But you don't want new growth produced at a time when it may be frosted. It will be safer to attack the decaisnea after it has flowered, in May next year. And if I cut it now, I would lose many of the seed pods that are one of the reasons for growing the shrub. They are weird, the size and shape of sausages, but navy blue.

The cotoneaster is different. It seeded itself into the bank and because there was nothing much else there at the time, I left it. It is Cotoneaster simonsii, with small, neat leaves and oval fruit, turning now to bright orange-red. It comes from Sikkim and Bhutan and makes generally upright growth, about 8ft tall. It's a shrub you can't find any fault with, but, at the same time, not one that ever stops you in your tracks, the way the aralia and the decaisnea do.

WJ Bean, author of the monumental, four-volume Trees and Shrubs Hardy in the British Isles, says C simonsii is "well able to take care of itself". Good. I needn't feel sorry for it when the saw starts to bite. Two of the upright growths have taken a decided turn towards the horizontal, consequently getting in the way of a pale pink fuchsia (F magellanica), which is flowering its head off at the moment. I have only been waiting for harvest festival to start rampaging round the cotoneaster. The branches will help decorate the font.

Removing big things, such as trees and shrubs, has the most immediate impact, of course, but sorting out the perennial understorey is no less important. Two things have happened to the detriment of the display on the bank. I have been far too easy-going about self-seeders such as alchemilla, brunnera and origanum, and I have let some plants, such as Iris sibirica 'Heavenly Blue', go on expanding until the clumps are at least 5ft across. No. I put that badly. No guilt. These plants deserve everything that is shortly coming to them. I'm off now with my favourite spade, to smash them to smithereeens.