6 plants you should never prune in October

ornamental grasses in autumn garden — (Image credit: Getty Images)

Jump to category:

1. Hydrangeas
Where to buy hydrangeas
2. Spring-flowering shrubs
Where to buy spring-flowering shrubs
3. Lavender
Where to buy lavender
4. Ornamental grasses
Where to buy ornamental grasses
5. Evergreen shrubs
Where to buy evergreen shrubs
6. Late-flowering perennials
Where to buy late-flowering perennials

With so much of the garden fading fast and dying back right now, it can be tempting to get busy with the secateurs and cut everything down for a neat look. But while many plants benefit from an autumnal pruning, there are certain plants you should never prune in October…and knowing the difference is crucial.

‘A tidy garden does not have to mean a completely bare one,’ says Pim Dickson, Senior Horticulturalist at Fothergill’s. ‘When it comes to October gardening jobs, it's a great time to remove diseased foliage, clear away rotting material and deal with damaged branches, but healthy stems, faded flowers and seedheads often have a purpose.’

‘One of the biggest mistakes people can make is reaching for the secateurs too quickly, as pruning at the wrong time can mean losing next year’s flowers and leaving plants more vulnerable to frost. By leaving the right plants untouched until spring, gardeners can protect them through winter and give themselves a better chance of enjoying a healthy, colourful garden next year.’

1. Hydrangeas

‘Hydrangeas are one of the most important plants to leave alone in autumn, especially mophead and lacecap varieties,’ says Pim. ‘These shrubs develop next year’s flowers on existing stems, so cutting them back in October can remove the buds needed for this.’

‘The faded flowerheads are also worth keeping in place as they can help protect the delicate buds beneath from frost. Instead, wait until mid-spring to prune hydrangeas, removing the old blooms and cutting back to the first healthy pair of buds.’

When it comes to what to do with hydrangeas in October, advice from the experts is to hold back on pruning, watering and feeding and instead focus on giving the roots some extra protection by adding a layer of mulch, like this RocketGro Magic Mulch, from £19.99, Thompson & Morgan, around the base of the plant.

Where to buy hydrangeas

2. Spring-flowering shrubs

‘Spring-flowering shrubs, such as forsythia and lilac, should also be left unpruned in October,’ advises Pim. ‘Many of these plants form their flower buds on the previous season’s growth, meaning an autumn trim can sacrifice the very flowers gardeners are hoping to enjoy in spring.’

‘The best time to prune spring-flowering shrubs is immediately after flowering in late spring or early summer, giving the plant plenty of time to produce new growth and set buds for the following year.’

If there are dead or diseased stems that need attention, these can be carefully cut back, either to the ground or back to a healthy side branch, but general pruning should always be left until spring. Check if stems are healthy by scraping the outer bark with your thumbnail - if the layer underneath is dry, brown and brittle, the stem is dead; if it is green and moist, the stem is still alive.

Where to buy spring-flowering shrubs

3. Lavender

‘Although lavender benefits from regular pruning to maintain its shape and prevent it becoming woody, a hard autumn cut can expose older stems that are less able to regenerate, while fresh growth may be damaged by cold weather,’ advises Pim.

‘The main shaping cut when it comes to how to prune lavender, is best carried out after flowering in late summer, taking care not to cut deeply into bare growth. For what to do with lavender in October, simply remove any broken or diseased material and leave more substantial pruning until the warmer months.'

Where to buy lavender

4. Ornamental grasses

‘The dry foliage and feathery seedheads of deciduous varieties of ornamental grasses can bring structure to a winter garden, catch the frost and provide food and shelter for wildlife,’ says Pim.

‘Cutting down ornamental grasses too early in October removes these benefits and can leave the plant’s crown more exposed to winter conditions. Leave the old growth standing until late winter or early spring, then cut it back before the new shoots emerge.’

Where to buy ornamental grasses

5. Evergreen shrubs

‘October is often a tempting time to tidy the garden, but it’s worth resisting the urge to prune certain plants,’ advises Charlotte McGrattan, Hardy Nursery Stock Buyer at Hillier Nurseries. ‘Evergreen shrubs such as viburnum tinus and viburnum ‘coppertop’ are best left alone at this time of year, while choisya ‘sundance’ and escallonia should also be left until after flowering if they need shaping.

‘Pruning evergreen shrubs like these now can remove developing buds and reduce the plant’s natural protection going into winter,’ adds Charlotte.

The best time to cut back evergreen shrubs is mid to late spring, after any risk of frost has passed and just before new spring growth begins.

Where to buy evergreen shrubs

6. Late-flowering perennials

‘Finally, it is worth leaving many late-flowering herbaceous perennials standing over winter rather than cutting every stem down to ground level,’ suggests Pim. ‘Plants with attractive seedheads, such as echinacea and rudbeckia, can provide food for birds over winter, while hollow stems and fallen foliage offer shelter for beneficial insects. Their dried flowerheads can also add height and texture to an otherwise bare winter border. Once new growth begins to appear in spring, gardeners can cut back the old stems carefully without damaging emerging shoots.’

Charlotte agrees: ‘Late-flowering herbaceous perennials, such as Japanese anemones, provide valuable structure and interest through the colder months. These can all be tidied at the appropriate time later in the season, rather than cutting them back in October.’

Where to buy late-flowering perennials

So don't prune your hydrangeas in autumn, but give them plenty of TLC and you'll help set them up for healthy growth next spring.

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Lisa is a freelance journalist who has written about interiors for more than 25 years. Previously editor of Style at Home magazine, she has worked on all the major homes titles, including Ideal Home, Country Homes & Interiors, 25 Beautiful Homes and Homes & Gardens. She has covered pretty much every area of the home, from shopping and decorating, crafts and DIY to real homes and makeovers and now regularly writes gardening stories for Ideal Home.