Autumn gold: beech hedge. Photograph: Alex Ramsay/Alamy

The crossover between autumn and winter is a fine time to take stock of the garden. You can see the forms of the trees and shrubs coming through again and though the perennials are all but spent, they remind you of what has been and gone.

Beth Chatto once said to me that an old garden is much harder to look after than a young one. She was speaking from the experience of starting a garden from newly cleared ground and living with its evolution over decades. A number of my own gardens are now in their late teens, with youthful vigour replaced by successes and failures. Trees that were once small will be casting their influence in shade and root. Hedges will have grown larger than intended. If dealt with on a regular basis, however, adjustments needed to keep things in balance are incremental.

Where perennial weeds have got into the beds, there are battles to be fought. A spring rosette of buttercup will have crept among its neighbours under cover of summer to become a colony by autumn. If you have bindweed, its roots will be a metre down and happy to live among the roots of your prized plants. Let us not dwell upon couch, ground elder or equisetum. One piece is enough to give you grief if they get the upper hand.

The bright green and red leaves of Epimedium x rubrum

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Shade lover: Epimedium x rubrum. Photograph: Mark Bolton/Getty Images

Then there are plants that you once thought of as treasures, that have done too well and might be erring upon the pernicious. Down at the farm I will act on the Rudbeckia laciniata, which is venturing too far, and the Tanacetum niveum, which has already spawned a million seedlings. You have to set rules or resign yourself to losing the neighbours that will inevitably be consumed by the more dominant plant.

A garden is a constant balancing act. Sometimes you need to be brutal with plants that are going backwards, as well as those that are too successful. Take a chainsaw to the deciduous hedges that have crept beyond their reach, to revitalise the ground underneath. Where soils are infested with roots, mulching and a handful of slow-release blood, fish and bone will help.

A dramatic act in an established garden will need to be carefully considered, but it invariably injects the energy a maturing garden needs to feel exciting again. Never be afraid to renovate a shrubbery with radical pruning to get the air back. Where a garden has fallen under the influence of woody plants that you would rather foster than remove, look at lifting their limbs. If the sun-lovers are no longer loving it, consider replacing them with a tapestry of shade-lovers. Epimedium and Symphytum ibericum will be more than happy in dry shade, while winter box and hellebores will inject out-of-season interest.

Though you might be feeling complacent or taking things for granted, a little change will find you in a dialogue with your garden, and happy that you have made the moves to keep things sprightly.

Get growing

Although deciduous plants are designed to go into dormancy, never prune evergreens at the onset of winter as they need their foliage to photosynthesise. Wait until March

Email Dan at dan.pearson@observer.co.uk or visit theguardian.com/profile/danpearson for all his columns in one place