IT'S early afternoon and the rain is falling. In an hour’s time I’ll go and water the sales plants. Correct watering of plants needs careful consideration particularly when the symptoms of overwatering, a limp sad-looking plant is exactly the same as under-watering. Watering, while essential is also time consuming so how to water effectively?

If a plant doesn’t need watering, don’t waste your time or risk over watering it. With pots, always make sure the compost is level with the collar line of the pot (Fig 1). This will give you space to fill with water which can then gently soak into the compost. If the compost reaches the rim of the pot, any attempt at watering will see the majority of it spill over the side, wasteful in terms of water use and your time. Our maxim here is that we water the pot not the plant (Fig 2).

So, how much water should you give each pot? Weight is a good indicator: pick up small pots and compare with their neighbours. You’ll soon get a feel for a well-watered pot against one that is drying out. Another indicator is if water runs quickly through the pot and out onto the ground, the plant is very dry. In such circumstances you may need to water again within the hour or better still put the pot in a soak tray overnight. If you use terracotta pots, tapping them with a wooden stick helps show if they need water. A dull sound and they are ok, a ringing sound indicates water is needed. If the compost is pulling away from the wall of the pot they will probably need placing in a soak tray.

When watering I’d aim to give the plant about 25 per cent of the volume of the pot. This may mean filling the collar area twice. Don’t try and water pots and hanging baskets in a hurry; it just spills over the side (Fig 3). Water should be applied slowly and allowed to soak through the compost eventually dripping out the bottom. On open ground with vegetable plots or flower borders I water only those plants looking limp and sad and showing stress, and I water the roots not the leaves.

To judge if a complete plot or border needs water ,use a trowel or your hand and pull back the soil until you reach moisture. This may be a few inches into the ground but once you have found it you need to think about how far down the roots of your plants are. Newly germinated root crops may only have roots going down two inches, so if dry to three inches then water. If the plants are well-established perennials and showing no sign of stress, there is no need to water. As for the sale plants the rain will be falling on the leaves and then dripping onto the floor. The rain is watering the plant not the pot hence the need for me to go now and water. Happy gardening.