Nip and tuck: Anna Pavord's summer pruning guide

If the recent wild weather didn't do the job for you, it's time to wield those secateurs and make some judicious cuts.

I was all set this week to write a calmly rational piece on summer pruning. Then the storm came. We're not unused to storms in the southwest, so I cursed only mildly yesterday as I hauled aside a tree that had fallen across our lane (it was only a smallish tree – I'm not pretending to be Tarzan). The stream regularly overflows the ludicrous pipe the council installed to send it under the road, so fronting the flood at the bottom of the valley, as I did today, with a bow wave mounding either side of the Subaru, isn't unusual either.

The storm is still hurtling round my hut as I write, with winds at storm force seven and more heavy rain to come. The ground is thick with foliage and branches torn from the fresh-leaved hazels. The apricot-coloured foxgloves, six feet tall, are flat on their faces, uprooted from the ground. The great clumps of cornflower that I allowed myself to be a little bit proud of (I wrote about them last week) are shattered and broken to bits. The long grass on the banks, at its most lovely earlier this week, interlaced with magenta-coloured vetch, lies sodden and flat. The rain has been torrential and the weight of it on trees, shrubs and plants, has made them hideously prone to damage. I'm looking at the twisted, broken stems of Salvia dombeyi, grown from cuttings taken last September. They were just about to break into flower.

The difference between summer and winter storms is that in winter, the wind meets less resistance and so creates less damage. Plants, at the moment, are in full, huge leaf. Heavy with rain, angelicas, fennels, thalictrums and euphorbias cannot stand up to the wind. Even the staked plants are blown flat. For gardeners, wind is the worst enemy. This storm has been blowing from the southwest, our most vulnerable aspect. The wind barrels up the valley and hits us full-on. I suppose our hedges must help us a bit, but at the moment it doesn't seem so.

On our top field, where I went to check that the gates hadn't blown open, I could scarcely stand up. Nothing makes you feel as impotent, as absurd, as screaming curses into storm-force wind and rain. You can't even hear yourself. The curses hurl away to be caught on the thorns of the hedges, to be drowned in the pelt of rain laying waste to the tall grass that we hoped to cut for hay.

But, such is the delayed nature of magazine publishing, you'll perhaps be reading this on a soft, sunny day with roses doing their June thing, and blackbirds singing happy melodies. Perhaps you never even had this cataclysmic storm and are wondering what land I'm living in. So for those lucky people whose pruning has not already been done for them by what I'll politely call 'natural forces', here are a few reminders about pruning that is better done now than later.

There's a simple way of remembering what needs pruning when. Shrubs that do their thing in the first half of the year should be pruned when they have finished flowering. Shrubs that flower in the second half of the year shouldn't. Why? Because if you prune them in these later months, they will put on a spurt of new growth beautifully timed to be cut to the quick by the frost and cold of winter.

Not all shrubs need pruning, whatever the time of the year. Abelia, acacia, acer, amelanchier, callistemon, cercis, corylopsis, crinodendron, daphne, eucryphia, garrya, for instance, can be left to their own devices, unless they run out of space, as garrya sometimes does. Then you need to cut back the advancing stems, but carefully. The best way is to track them back to the point where they join another, bigger branch and make your cut there. This is a much better option than butchering round the entire shrub.

The big, waving stems of Rubus tridel 'Benenden' need tackling every year when the shrub has finished flowering. With us, that is now. When established, this rubus can throw out branches from the base that quickly get to 3m (10ft) or more. When they are this long they arch over and lay themselves heavily on whatever happens to be underneath. 'Benenden', though, is a wonderful thing for a wildish garden like ours, covered in May and early June with white flowers, the size and shape of a wild rose, but without the thorns. To contain its exuberance, you need to creep in underneath the arching branches and cut out some of the longest and oldest growths. Already, you will see bright new stems (they look a bit like raspberry canes) springing from the base. Since these will be shorter and more productive than the old branches, it pays to encourage them. Pruning out old growth does just that.

Choisya, the Mexican orange blossom, does not grow at the rate of rubus. Even at maturity it will scarcely be more than 2.5m (8ft) high and wide. But the older this shrub gets, the stragglier it becomes. It's worth thinning out a few of the oldest branches each year to encourage fresh growth to shoot from the base. Sometimes, too, the foliage is cut by frost, after which it blackens and dies. If you haven't done it already, get rid of this eyesore now.

Some shrubs, such as broom, get extremely lax and untidy if they are not pruned every year when they have finished flowering. But you have to be careful with broom (Cytisus scoparius and its cultivars such as 'Burkwoodii', 'Cornish Cream', 'Firefly', 'Golden Sunlight', 'Goldfinch', 'Windlesham Ruby' and 'Zeelandia'). Cytisus scoparius flowers on growth made the previous season and this is the stuff you should cut, shortening the shoots that have flowered to within 5cm/2in of the old wood. If you cut right back into this old wood, it won't sprout. But if you neglect to cut back the newer growth, you'll end up with a broom that is bare at the base, leggy and wobbly.

Sometimes, the way you grow a shrub will dictate whether you need to prune it or not. As a free-standing bush, japonica (Chaenomeles speciosa) can be left alone. But it's often used as a wall shrub, with its branches pinned back against a support. In this situation, you don't want too much growth coming forward from the wall or fence. The best way to keep on top of it is to cut back the previous season's growth now, leaving just two or three buds in place. But what to do about a pear tree with a huge branch untimely torn from its side by the wind, the books don't tell you. Just weep.