Plants need a reliable supply of water for germination, growth, flowering and fruiting. Water is essential for the uptake of nutrients from the soil as well as temperature regulation. Although plants have diverse requirements for water, here are some useful general guidelines on watering your plants.
In dry conditions, established plants benefit from thorough and infrequent watering rather than a daily splash.
Plant roots will only grow into moist ground, so if the soil is dry below and damp above, roots will be concentrated around the surface. Occasional heavy watering encourages plant roots to grow downwards where there is a more reliable water supply and source of nutrients.
Unless you have a natural spring or stream in your garden, the best source of water is the mains.
Before watering lime-hating plants though, check whether your mains supply contains lime.
Rain barrels can be used for watering plants growing in the ground but never for containerised plants. This is because phytopthera fungi, often present, can infect and kill such in confined conditions.
Learn how to identify whether your plants need watering.
For plants in containers, you can judge by the weight of the container or by pushing your finger inside the pot to assess the dryness of the soil.
In the garden, the best time to water is in the evening. Water the soil underneath the leaf canopy, not the leaves, and mound the soil to make a basin shape for better drainage.
Top priority should be given to newly-planted specimens. With bedding plants inserted directly from cells or pots, keep the soil moist for one month after planting.
Trees and shrubs planted from containers will need watering for longer – they will need this extra watering for up to a year after planting to make sure they are established.
If a plant is wilting or the leaves look dull or rolled up, it needs watering immediately. The best technique is to shade the plant and spray the foliage with clear water. Then drench the soil and allow the surplus to drain away.
Vegetables grown for their leaves – such as lettuce and spinach – should be kept consistently moist. Others grown for their seeds – such as peas and beans – should not be watered before flowering as this will encourage leafy growth and few flowers.
Watering when in flower results in the production of more and juicier vegetables.
If water is in short supply, your potato crop can be increased by a heavy watering about ten days before harvest.
To reduce the need to water, dig in organic material when planting and apply a 50-75mm (2-3in) layer of mulch.
Newly planted and young seedlings should receive a fine mist from a hosepipe spray attachment or a fine rose from a watering can to avoid disturbing the roots. The tougher or older the plant, the more vigorous the watering can be.
Sprinklers are useful for large areas of the garden but remember that watering bare soil will result in the growth of more weeds. It is a good idea to leave a few straight-sided containers on the ground to catch the water and give an idea of how much has been applied. A 25mm (1in) depth would normally be sufficient for each watering.
If you’re going on holiday, you can leave your houseplants with a reservoir of water by placing them on the draining board on capillary matting that trails into a sinkful of water.