How Kew Gardens stays green in a drought While companies deny that "drought police" will enforce the rules, they are relying on people to report neighbours for disobeying the ban. And customers are panicking: sales of water butts at Homebase are up 340 per cent, while watering can sales have risen 56 per cent since last weekend. In leafy Kew, though, the drought could be a problem for another world. But there's a reason the royal gardens are blooming while the rest of the nation is parched. "Under the National Heritage Act 1983, plants from the scientific collection are exempt from the ban," explains Barnes, who has worked at the gardens for 24 years. This applies to rare species, such as orchids and flora from the Canary Islands and Madagascar. We also have two cacti of which there are only three in total on earth. It's like having a dodo, so we have a duty to keep those alive. But the exemption doesn't cover Kew's entire collection. Lawns cannot be watered by hosepipe; neither can common plants and shrubs. Barnes is keen to dispel a few myths. We no longer get our water from the Thames. Secondly, we don't have our own private reservoir. And we don't water our grass. I remember dry spells where the lawns have turned straw yellow, but within the first few days of rain they come alive again. It's a natural cycle. The Kew team have refined their knowledge of capturing, preserving and recycling water over 170 years. Since the gardens were founded in 1841, various schemes have been adopted to deal with the recurring water shortage. In 1850, a steam engine pumped water from the Thames through a pipe near Brentford Ferry. A well and a lake provided later solutions, but the latter dried up during the drought of 1921. Unknown to most of its 1.5 million annual visitors, Kew relies on underground pipes to pump water to sprinklers and faucets around its 300 acres. The roofs of the palm house and conservatory are also designed to collect rainwater, funnelling it to subterranean reservoirs. Barnes says Kew's water policy is "strict but sensible." We try to set an example of responsible use. This is a terrible place to grow plants - the soil is sandy and gravelly because of its proximity to the river - but we never use hosepipes excessively. Tony Kirkham, head of the arboretum, is responsible for managing Kew's 14,000 trees. He says gardeners should adjust planting patterns. We do more autumn planting than we used to. Trees can still root from September to December, as the ground is warm enough, and this gives them a head start for spring. Kew gardeners also use "treegator" watering bags - a slow-release water container that is zipped around the trunk - to top up supply in younger trees. A recent spate of dry springs has changed the type of plants grown in the royal gardens. A list released last week by the Royal Horticultural Society recommends drought-friendly species that can grow domestically. These include ruscus, bergenias, euphorbias and sedums - all of which abound at Kew. In the Mediterranean display, the air is thick with the scent of lavender, mingled with thyme and rosemary. "Herbs are great in dry conditions," explains Kirkham. Anything with fine or hairy leaves, or plants containing natural oils - such as geraniums - have a built-in ability to cope. One of Kew's best water-saving measures is mulching. A mixture of manure - delivered daily from the Royal Horse Artillery - and shredded wood or herbaceous waste, it's formed when bacteria and fungi break down the raw ingredients and is then laid around the plant base or dug into the soil. Up to 250 cubic metres of mulch is produced each fortnight, after which it's lined up in steaming "wind rows" to decompose. "Because all that activity is taking place inside, it gets really hot - up to 70C," says Barnes. Gardeners used to stick a jacket potato into the middle when they got to work. By lunchtime it would be cooked through. Mulching saves Kew up to £500,000 a year in waste disposal and compost. It's great during a hosepipe ban, because it suppresses weed growth and helps plants keep in water by stopping evaporation. So how else can domestic gardeners survive the ban? Water butts can be installed to conserve rainwater. I have six at home, running from the tops of glasshouses and sheds. Each one holds up to 46 gallons. You should also avoid over-watering plants. Be aware of how much liquid you're using and recycle when you can. Barnes admits his job is made easier by the gardens" partial exemption from the hosepipe ban. But, even at Kew, they will spend this weekend praying for rain. We have come to expect January to March to be dry months, but you know what they say about April showers... He looks towards the sky. It's about time that came true.