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Gardens in the UK generally need around 2.5cms1 of water a week to keep plants healthy and growing well. It's possible that in hot, dry weather, this amount of rain will not fall, so it's important to water the garden yourself from time to time. Trying to do this while conserving water can test the ingenuity of any gardener. This entry concentrates on the garden itself, and avoids greenhouses and all types of containers. It gives hints and tips on how to make the most of the water that does get to your plants, both by nature and by nurture.
One great way to conserve water is to have as many water butts2 as you can afford and to have space for them so they can collect rainwater. Fit guttering to the shed, the greenhouse and fit water butts to them. Use all the drainpipes on the house as well. Butts can even be fitted to the pipes that remove waste water (grey water) from sinks and the bath. However, if you use detergents then the water should only be used if they are bio-degradable, environmentally friendly and diluted with rain water3. Don't use grey water to water any plants that you want to consume, and make sure that you avoid the plants, but rather, water the soil instead. If you can show that the water from your house doesn't go into the sewerage system, you may be entitled to a rebate or discount from your water supplier. All water butts should be covered, to prevent wriggly things from making their home there.
During times of infrequent rain the best time to water the garden, surprisingly enough, is when it is raining. If your garden is not getting its 2.5cms of water a week, this is the time when the least amount of evaporation will occur. Use up any water that is already in the butts, to make way for the new rain. Remember that rain water is slightly acidic so give generously to acid-loving plants.
Don't use rainwater on seeds or seedlings. It can carry fungus spores, which will harm the young plants.
The best time for watering when it's not raining is in the evening. Evaporation will be low as the sun sets, giving the plants time to absorb the water before the morning. You'll also be able to enjoy the plants that only release their scent in the evenings. Early morning watering is better than doing it in the heat of the day, but evaporation will be higher.
Seep hoses are porous pipes that seep water along their length. This is especially good along rows of vegetables, and can be buried just under the surface to deliver the water exactly where it is needed. They are usually made from recycled tyres. A similar idea is the use of perforated hose pipes. These have holes along the length and work in much the same way.
Give the garden a good watering, thoroughly soak the soil, and then mulch it. This means covering it with organic matter so that the water doesn't evaporate so quickly; water will still penetrate down to the plants. There are many kinds of mulches that can be used, and they have the added benefit of helping to keep weeds under control.
Bark - Normally shredded or chipped, bark is a good choice for trees, shrubs, roses and in perennial beds. Bark is the most attractive mulch.
Straw - Strawberries and tomatoes especially appreciate a mulch made of straw, but you do have to have a thicker layer than with some other mulches, and it doesn't look very tidy, especially in high winds. It will rot down into the soil quite quickly, but if you have pet rabbits or small rodents, you will find that you have an inexhaustible supply.
Grass - Grass has the benefit of being free, and is a good way of getting rid of lawn clippings. Use a thinner layer than straw, to prevent an unsightly mess, and watch out for the grass taking root. Don't use grass that has gone to seed, or if your lawn has weeds in it that you don't want in your borders.
Newspaper and cardboard - Newspaper and cardboard can be used, although they should be wet and buried under another mulch or garden soil to prevent it blowing all over the garden. It's best to shred the newspaper. Don't worry, the print shouldn't harm the plants.
Leaves - Although usually encouraged to put fallen leaves in a perforated rubbish bag and left to rot for a year, the keen gardener will realise that leaves can be put straight onto the borders. The disadvantage is that they are usually available at the wrong time of year.
Ground cover plants - These are plants that are low-growing, and fast growing. They will cover the ground very quickly, and prevent evaporation.
No, no, no. They are a waste of water. They use the same amount of water in an hour4 that a family of four uses in a week. Watering by hand gives you time to inspect the plants close up. You can enjoy them much better close up, and you can spot problems easily. Some water companies will insist that you fit a water meter if you intend to use a sprinkler. They lose water to evaporation before it even gets on the soil. Lawns don't need them; if they go a bit brown, they'll soon recover when it rains.
Other Things You Can Do
Weed carefully. Make sure that every drop of water is going to a plant that you want, not a plant that you don't want.
Planting Mediterranean plants means that they won't need as much water; they will enjoy the hot, dry months without forcing you out of the house with a watering can every evening.
Plants watered little and often develop shallow roots, which means they are seeking water where it's not going to be found easily, or for long. Giving them a thorough soaking once a week means that the lower roots will develop, and the times of drought will force the roots to grow deeper to find water for themselves.
Leave grass at least three centimetres long.
Group plants together wisely. If all the thirsty plants are in the same place, then they can be watered together, which will help to conserve water. Planting them in a shielded spot will also cut down on drying winds.
Bury homemade funnels beside the plants most likely to suffer from drought. This puts the water straight down to the roots, and prevents water from running off the soil where you want it, which is very important if you are gardening on a slope.