麻豆传媒

LAST month, a campaign by the gardeners to be more environmentally friendly. One piece of advice was to get a water butt and use .

You might think there is plenty of water to go around in a rainy country like the UK, but it is a waste of energy to give plants tap water, which has been intensively treated so it is fit to drink. Rainwater is perfectly good enough for most plants and may even be better, as tap water contains dissolved magnesium and calcium, which accumulate around the roots, raising the soil鈥檚 pH and lowering the availability of other nutrients. The only exceptions are tiny seedlings, which benefit from clean tap water as they are vulnerable to infections.

If you have room to install a water butt, make sure the water doesn鈥檛 accumulate organic matter, which will lead to algal growth, says , Bristol, in the UK. Use a lid, and put some fine netting where the downpipe meets the lid to stop leaves getting washed in.

Phillips says we should try to avoid using hosepipes in the garden: they can use 1000 litres of water an hour, more than the average household in a day. 鈥淚t鈥檚 just so easy to get the hosepipe on and spray huge quantities of water about,鈥� he says.

It is better to use watering cans to direct the water to where the plants need it. And rather than watering little and often, which encourages shallow roots, give big, less frequent drinks for deep roots.

Another option is making a drip irrigation system out of an old 2-litre plastic drink bottle. Just nail a few holes in the lid, fill with water, put the lid back on and partly bury it upside down, where it can drip-feed water directly to the roots.

To reduce the garden鈥檚 need for water over the longer term, stay on top of your weeding 鈥� some common weeds suck up four times as much water as crop plants do. Add an organic mulch-like manure to reduce evaporation from the surface; as the mulch gets mixed in over time, that will help the soil hold more water too.

Water-retaining silica gel granules work well, but are too expensive for widespread use. I use them for hanging baskets and pots, and also mix some into the soil under particularly vulnerable plants like tomatoes.

You can also research when plants require the most water so it isn鈥檛 wasted. Tomatoes, for instance, need this when they start flowering and fruiting, but the majority of squash varieties require more water when first planted. If you are growing large, rambling squashes like courgettes and pumpkins, don鈥檛 forget to put in a small cane next to the young plant, so you will be able to find the roots and water them when autumn comes and it is an overgrown monster.

For other projects visit聽newscientist.com/maker.