One mistake thousands of gardeners are about to make that could ruin your hydrangea

With autumn here, there are plenty of jobs to get done in the garden to prepare your plants for a cold winter and get them ready for next summer's bloom.

But while you think one common gardening task is doing your plants good, experts have warned that it may be doing the opposite.

Pruning is a very common practice for gardeners, generally used to cut away dead, diseased or overgrown branches and leaves to promote even better growth for next season.

But while it may work for many plants, some more delicate plants would benefit from a trim much later on in the year. Hydrangeas in particular are at risk when pruned in autumn and winter.

The plant's trademark bunches of flowers are what make them such a popular choice, but when they start to fade at the end of summer, it may actually be best to avoid deadheading and leave them be.

According to experts at the RHS, the flowers provide great frost protection to the young buds and shoots over the winter, making for an even better bloom next summer.

The society added: "Although the blooms on mophead hydrangeas can, in mild areas, be removed as soon as they have faded, it is best to leave them on the plant over winter to provide some frost protection for the tender growth buds below.

"Remove the dead flowerheads in early spring, cutting back the stem to the first strong, healthy pair of buds down from the faded bloom."

For anyone with lacecap hydrangeas in their garden, feel free to prune, as the species is much more resistant to the cold weather. A simple trim back to the second pair of leaves below the head can prevent any seeds from growing, which will keep the energy inside the plant.

Once spring rolls around, the threat of frost has all but disappeared, so a quick prune before any new growth has begun will give your plant the best chance for a great flowering season when summer hits a few months later.

Pruning in early spring will now help them reach a manageable size, improve their shape, and stimulate new growth for more and better flowers.

However, if your plant has been left in poor shape after this summer's brutal heatwaves, it may require more drastic action. The experts added: "Overgrown or poorly shaped plants can be entirely renovated by cutting off all the stems at the base.

"However, this will remove all the flowers for that summer. The new stems won't bloom until the following year."

Another task ideal for hydrangeas in September is starting to adjust your soil pH. The plants love slightly acidic soil, but it can take time to increase your garden's acidity level, and by adding special fertiliser now, it gives plenty of time to create the perfect conditions by spring.