The kindest cut of all: Now is the time to let your plants and shrubs know who's boss, so sharpen the secateurs and get snipping, says Anna Pavord

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Plants present many of the same characteristics as children. The intense period of bringing them on, worrying about the right food and so on, is followed by an equally intense period of trying to hold them back. There's no equivalent to pruning in childcare, but gardeners have this one advantage over parents. It is a mistake, though, to look at secateurs as offensive weapons. Good pruning is a matter of working with, rather than against, a plant. The most important thing, before you make any cuts, is to have clearly in your mind the essential qualities of the plant you are about to attack.

If you have a tall, upright shrub blocking a view in the garden, it is pointless to chop the top off it each season in an effort to refashion it as a short, fat shrub. Instead, you must come to terms with the irritating fact that you or the previous owner of the garden have planted it in the wrong place. Either way, it should be moved rather than heavily redesigned.

Some tall, upright shrubs, such as philadelphus or May-flowering kerria, do need regular pruning, but this is not to make them shorter. It is to ensure a plentiful display of fresh new growth that will flower more freely than the old.

Pruning is something we impose on shrubs, for our own ends rather than theirs. Shrubs do not die if they are left unpruned, as anyone who has taken over a neglected garden knows only too well. Away from the flashing knife, jasmine just keeps getting bigger. So do pyracantha, forsythia and weigela.

Pruning is a useful tool in erecting the delicate barrier against chaos that is at the core of garden making. A garden is a construct, a reordering of the elements - earth, water, leaves, flowers - that exist untrammelled on the other side of the barrier.

Armed with secateurs and some strong long-handled loppers, you become a sculptor, releasing the forms suggested by the material to hand. With overgrown shrubs you have a choice: sculpting or moulding.

The second is the more drastic: cutting the whole thing to the ground and working with the new growths that spring up the following season. This is the best course to take if you want to move a shrub. Unencumbered by top growth, it will be easier to manhandle. It too will find the business of putting down new roots easier if it does not simultaneously have to send food and drink up to the top storey.

This is what I am going to do with an Alba rose that took advantage of the summer's perfect growing conditions to become ridiculously large and blot out the planting behind it. Once I had become irritated by it, I saw how little it was contributing after its brief, though admittedly heady, season of flowering. It needs a less prominent position. Cutting it down and moving it will be a good New Year's Day job.

Sculpting is more interesting. Take the philadelphus, which by nature grows in a multi-stemmed thicket, sending up fresh growths from the base. A neglected shrub, 20 or more years old, can spread 12 feet. The oldest stems will be buff-coloured, often covered with a dusty green mould. The youngest, this season's growth, are pale green, springing from the ginger-coloured stems made during last year. These will have large, lush leaves, better than anything coming from the old wood.

A few obvious targets usually present themselves for pruning: messy, twiggy stunted growths round the base of the philadelphus for a start. Take these away and you may begin to visualise a narrow fountain shape locked up in the philadelphus, stems growing upright and then arching slightly at the top.

One or two branches will usually be sticking out, spoiling the line. Trace these down as low as you can and cut them out entirely. Cruise round the shrub while you are working, to see what it looks like from other angles. Do not make all your cuts on the same side.

Inevitably, some good new wood will come away with the old. This cannot be helped. It will quickly be replaced. As a rough rule of thumb, you should reduce the overgrown shrub by about a third, each year taking out the oldest wood. Within three years, you will have rejuvenated and reshaped the whole bush. Even one year's attention can do wonders.

Avoid cutting branches halfway along their length. If a branch is stretching across a path and you want it out of the way, trace it back to its source or to its junction with another branch and make the cut there.

In the great clean-up that takes place between now and the onset of winter, there's a tendency to snip away at everything, reducing all shrubs, whatever their habit, to barbered buns. Resist the temptation. The garden may be tidy, but, by reducing all the shrubs to the same common denominator, you will have missed the point of growing them at all.

In the most general terms, shrubs that flower in the first half of the year do so on growth made the previous year. These can be pruned after flowering. Shrubs that flower in the second half of the year bear the flowers on the new wood they have made in the first half. These are best not pruned straight after flowering, but left until early spring the following year.

Pruning kicks a shrub into top growing gear. 'Crumbs,' it says to itself, 'someone's trying to do me in,' and it pumps energy into dormant growth buds lying along its stems to replace what it feels it has lost.

If you pruned a late summer-flowering buddleia or caryopteris when it had just finished flowering, the resultant tender, new growths would coincide fatally with the first frosts. So you leave them until spring before pruning. This checklist of common shrubs may help new gardeners to decide which needs what. And it will stop shrubs from being given unnecessary autumn haircuts.

Don't prune regularly, just thin occasionally and remove dead shoots: abelia, abutilon, acer, camellia, evergreen ceanothus, cotoneaster, cytisus, elaeagnus, fatsia, genista, hamamelis, hibiscus, hydrangea, magnolia, osmanthus, pyracantha (but can be trimmed to shape in May-July), rhododendron, senecio (cut back flower stems in autumn), skimmia, syringa.

Remove one third of oldest shoots in spring or after flowering each year, to encourage fresh flowering shoots: berberis, choisya, cotinus, deutzia, escallonia, forsythia, hydrangea (or leave unpruned), winter jasmine, kerria, philadelphus, phlomis, potentilla, ribes, rosemary, spiraea, symphoricarpos, viburnum (early flowering), weigela.

Cut back hard in spring: buddleia, caryopteris, deciduous ceanothus, ceratostigma, cornus (foliage forms), fuchsia (frost usually does it for you), lavatera, perovskia.