using grey waterThere is quite a lot of information around on what to do with water if you have too much or too little of it. But how much of this information can we believe? On behalf of gardeners the RHS monitors the latest research and passes on the most reliable information as applicable.

Our research into water is looking at the most efficient use of water for optimal growth in a range of growing media. Gardeners need to understand how much water plants actually need, and when and how to water for the best results.


Water management

Plants need to be watered correctly. There should be enough to wet the top 30cm (12in) of soil, where most plants’ roots should be. Too little water just wets the soil surface and either does not reach the roots or encourages them upwards where they tend to dry out. Too much water will drain out of reach of the roots, or waterlog the soil causing root rot.

With this in mind, it is important to manage the water in a garden to ensure there is an optimal amount all year round.

More on managing water in gardens

More on dealing with drought

Watering baskets and containers

Baskets and containers are notoriously thirsty, making them the most labour-intensive of all watering maintenance. An RHS-funded experiment was set up to look at the best way to water baskets and containers, with important results for all gardeners.

RHS experiment on watering baskets and containers

Using grey water

Domestic waste water, known as 'grey water', may also be used in the garden. This may be from the kitchen, the washing machine or baths, basins and showers. It should be used with care, but can be useful during times of water shortage.

Advice on how to use grey water


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The Royal Horticultural Society is the UK’s leading gardening charity. We aim to enrich everyone’s life through plants, and make the UK a greener and more beautiful place.