An alternative to hand watering your garden is to install an irrigation system or a sprinkler
and attach a water computer
to your tap. You can program the water computer to water your garden at the ideal time, in a way that directs the water onto the garden where it is needed via drippers and sprayers in the irrigation system, or that covers a larger patch if using a sprinkler. This way the garden can be taken care of before you even get out of bed in the morning, giving your plants an ideal start to the day.
When watering, it is better to give a deep watering every couple of days rather than a short sprinkle every day. If your soil is good at retaining moisture then you may only need to water once a week, but for more free draining soils, you would be better off watering every other day. Make sure you water deeply as a shallow watering encourages roots to develop just below the surface of the soil, where they are at risk from the drying effects of the hot midsummer sun. A soil wetter can help to ensure the moisture penetrates deep into the soil.
The kind of plants you are growing also determines how much watering you need to do. Lavender likes things a lot dryer than a thirstier canna lily. It is important to find out what your plants like, so you don’t kill them with kindness. Some plants will need much more than others, for example, in hot weather, a tree will need at least 38 litres of water for every 2.5cm of its trunk diameter every week.
This still doesn’t answer the question – how much water is enough? There is a general theory that states that a garden needs between 2.5–5 cm of water each week - but what does that actually look like? The best way to find out is with trial and error. After watering, dig down beside your plant, but far enough away so you don’t damage the roots. If the soil is moist down to 10 cm or more then you are doing well. You can also get a soil meter to show you how dry the soil is getting or put a rain gauge in where you are watering to see how much is being delivered to your plants.
Your plants will soon tell you if you are watering too much or not enough as they will wilt easily, or the leaves will turn yellow and drop off. These are signs for over and under watering. However, with more established trees and plants the damage may not be evident for several months.
A good thick mulch can help lock moisture into the soil to reduce the need for frequent watering and has the added benefit of preventing weeds.
So, at the end of the day, knowing how much to water your garden comes from knowing your garden. Once you work out what it takes to meet its need, you will have a healthy, flourishing garden to enjoy.