A gardening expert from Classy Flowers has shared how to revive a "wilted" hydrangea using a simple watering technique.

In a video on YouTube, @Classyflowers, who has 338,000 subscribers, reassured gardeners that a wilted, dry hydrangea can be revived in just a few hours.

The hydrangea, which was planted in a container, had wilted flowers that looked dry and almost dead. However, the expert assured that hydrangeas can collapse and look wilted after short breaks between waterings or after extreme heat.

She described hydrangeas as a "very moisture demanding plant" which is why people often throw their container plants away when they're dehydrated as they can look dead.

However, she said hydrangeas "can almost always be brought back to life and very quickly".

She continued: "So how [do we] get hydrangeas to hydrate quickly and efficiently? I often hear that many people, when even watering the plant, do not get the result, or it takes a lot of time. I'll show you how you can reverse dehydration just in a couple of hours."

Gardeners may notice the roots of the hydrangea and the soil inside the container are dehydrated.

If the pot is watered from the top, then the very dry, crumpled earth, saturated with air is not able to absorb moisture and all the water is simply going to flow around a lump of soil and then pour out.

Instead, the gardening expert suggested gardeners need to water their plants using an "immersion" technique to ensure the soil gets completely saturated.

The gardening expert prepared warm water by adding boiling water into a bucket of colder water. She added: "Temperature is a catalyst for biological processes and this will significantly accelerate the hydration."

The temperature of the water is very important - the water can't be too hot but it must be tolerable for your hand. Very hot water can damage dehydrated roots.

Next, spray the entire bush thoroughly with water to stop the evaporation of moisture from the leaf surface.

Lastly, the gardening expert recommended, "heating the roots from below and stopping evaporation from above". To do this, put the hydrangea in a cool room with a temperature of 5C to 10C.

The gardener set up a time-lapse video which showed her plant "coming back to life" in a matter of hours.

Some of the flowers didn't come back to life as they were at the point of death which cannot be reversed.

Once your plant is hydrated, remove all of the dead parts of the plant - the flowers and the leaves - to avoid bacterial and fungal infections.