How to Water Plants
From: DK Books - How to Grow
Most plants need water, but concentrate on those in containers, where the soil dries out relatively quickly; newly planted specimens that haven't yet developed a strong enough root system to cope on their own; and fruits and vegetables at key stages in their growth cycle.
Preserve Water Supplies
Water is a precious commodity, but if you irrigate only those plants that need it, and water in the cool of the morning or in the evening, you can greatly reduce your impact on supplies.
Other ways to minimize water usage are to add moisture — retentive gel crystals to containers, and mulch borders every year after it has rained. Trees, shrubs and perennials will also need watering less frequently during the first few months if you plant them when the soil is naturally moist in autumn, winter and early spring. Lay turf in late winter and early spring, too, and it will usually establish well without the need for extra irrigation.
After planting, encourage deep rooting by watering thoroughly and then leaving for 7–14 days before watering again, rather than giving frequent small doses. The water will then sink deep into the soil and encourage roots to follow. Also, if planting in the rain shadow of walls and hedges use drought-tolerant species.
Different Watering Methods
Make the most of your water supplies and save yourself time and energy by using a watering method that suits the job at hand. A watering can is ideal for small areas where you want to target water accurately; hoses are best for large beds, but use them with care to avoid waste.
If you only have a few plants or pots to water, use a watering can, and pour slowly so it has a chance to soak into the roots; remove fine roses from cans unless watering new plantings. Direct water to the roots of your plants — they do not absorb water through their leaves so spraying overhead is not only wasteful but means that less moisture reaches the soil. Also avoid flowers and fruits, which may rot if too wet. Mound up the soil around the base of large plants to create a reservoir in which water will collect and sink down to the root area.
When hosing beds and borders, focus the spray on the soil, and turn it off as you move between planted areas. Long-handled hoses are useful if you have lots of pots and baskets to reach — again, turn the flow off between each container. Long-handled hoses allow you to direct water to less accessible plants, such as vegetables in a large bed, without treading on the soil.
Using Automatic Watering Systems
Relatively easy to install, automatic watering systems can save hours of work in the garden; attach a timer, and they will water your plot in your absence. Most come in kit form and allow you to design a system that suits your garden. Kits typically include a network of main pipes into which you insert fine feeder pipes that take water directly to individual plants or pots. These terminate in small drip nozzles, held just above soil level, that gradually release water, which drains down around the roots. Check your watering system every few weeks to ensure plants aren't being under- or over-watered, and adjust individual flow regulators as necessary. Turn off nozzles when no longer required. Set water timers to come on every day or week, in the morning or evening to minimize evaporation, and alter the program if the weather changes.
Using Perforated Hosepipes
Less sophisticated than automatic irrigation systems, these perforated hosepipes are perfect for watering lots of plants at the same time. Unlike a regular hose, water gradually seeps out at soil level and penetrates deeply. Lay one along a row of thirsty vegetables, or weave it between newly planted shrubs and perennials. Attach the hose to a water butt, which may need to be raised up to provide a gravitational flow of water, or fit on to an outdoor tap. Lift your hose and reposition it as needed. The most efficient watering method if used correctly, seep hoses trickle water into the soil exactly where it is needed.
Although large containers need watering less frequently than small ones, they may still require water every day in summer. Porous terracotta pots dry out quickly, so consider lining them with plastic before planting. Don't rely on rain to water your pots because the soil often remains dry after a shower. When planting, leave a gap of at least 1 inch between the soil and the pot's rim to allow water to collect there. A bark or gravel mulch helps retain moisture. Direct water onto a piece of broken pot to help prevent compost being washed off the roots.
Help trees establish by inserting perforated drainage tubing into the hole, close to the roots, at planting time. Water poured into the exposed end is directed to the root area with no wastage. Mulch, or use a tree mat, to deter weeds and to seal in moisture.