Never prune these plants in August if you want them to flower again next year

It’s a busy, busy time out in the garden, but this month, you’ll need to watch where you use your secateurs – because there are some plants you should never prune in August.

Trimming certain shrubs, trees and flowers this far into summer can damage them, and even ruin next year’s blooms, depending on when they’re set to flower. There are plenty of plants you should prune in August, though – but that’s another article.

I’ve pulled together a list of plants you should never prune in August if you want to get your 2026 garden off to the best possible start. Give it a quick glance over before you get the pruning shears out!

1. Late-flowering perennials

A lot of plants won’t have finished flowering yet, even if the first round of blooms has fallen off (you'll know that if you've been deadheading your perennials for a second bloom) – and those are precisely the plants you should never prune in August.

‘By pruning perennials and shrubs which flower late into the summer months and early autumn, like hydrangeas, asters, dahlias, nerines, rudbeckias, heleniums, japanese anemone and chrysanthemums, you risk cutting off buds which are still set to flower, resulting in less blooms,’ warns Helena Jones, gardening expert and head commercial at Hedges Direct.

If you’re growing climbing hydrangeas, though, it’s generally safe to prune those now. ‘Climbing hydrangeas can have a gentle tidy-up after flowering, but it’s important to check the variety before cutting,’ says Julian Palphramand, head of plants at British Garden Centres.

There are plenty of perennials you can plant in August for flowers all the way into the autumn months, like the stunning Anemone × hybrida 'Königin Charlotte' from Crocus.

2. Spring-flowering perennials

Buds are the buzzword when it comes to plants you shouldn’t prune in August. Shrubs that are set to bloom in spring are already preparing for just that – and pruning them now could remove developing buds and spoil next year’s displays.

‘Spring-flowering shrubs like rhododendrons, azaleas, camellias, forsythia, lilac and early viburnum are already making next year’s flower buds in late summer,’ explains Julian.

If you’re in the market for a spring-flowering perennial and keen to learn how to grow camellias, it's worth picking a variety like Camellia ‘Blooming Wonder Pink’ from Thompson & Morgan, which produces beautiful, soft pink blooms.

3. Early-flowering evergreens

Early-flowering evergreens are also forming next year’s buds already, so you’ll need to steer clear of those with the secateurs this month, too.

‘Evergreens like berberis, choisya, and daphne are also budding for next year, so pruning now not only risks losing flowers, but can also produce tender new growth that colder weather may damage,’ Julian explains.

There are plenty of evergreen plants for pots and borders that provide greenery all year round, but if you want the best displays from flowering varieties, it's crucial that you don't prune them at the wrong time.

4. Apple and pear trees

If you’re wondering when to prune apple trees, or the best time to prune pear trees, August isn’t it – and going too heavy with the loppers could damage your fruit tree.

‘Light summer pruning is only suitable for types such as espaliers or cordons,’ says Julian. ‘Regular bush-shaped fruit trees like 'Conference' pears and 'Cox' apples should be pruned in winter, during dormancy.'

'If you prune apple trees too soon, this can stress the plant, and any new growth will be susceptible to disease,' agrees Paul Parker, CEO of bulbs and perennials specialists J. Parker’s.

You could always plant a potted fruit tree this month, instead. Pear ‘Mini Conference’ from Thompson & Morgan is perfect for smaller gardens.

Even if you can't prune the plants from this list right now, there are still plenty of jobs to do in the garden in August that'll keep you busy.