Article written by Emma Urquhart
How often should I water my garden? Asking this question I guarantee you will get a different answer from everyone, often contradicting what you have already heard.
So what's the right way? It differs for everyone! Climate, soil and plant types are your big variables in this topic. But you can make things really easy for yourself. Soil moisture testers are cheap and take away all guesswork. They have a probe that you poke down into the soil and it reads how much moisture is down around the roots, which tells you whether you need to water or not.
Another way you can measure is to dig your trowel in and wiggle it just enough to part the soil to put your hand in for a feel. If your hand comes out and the dirt just brushes off, then the soil is dry, meaning you may need to run a sprinkler over it for a period of time to let the water soak down to the root layers. If the soil sticks to your hands then you don't need to add water your garden just yet.
Water is an important requirement for plants. All those nutrients you have have been putting in the soil get dissolved into a solution which is then taken up by the plants. This is where good soil structure becomes important. Soils with low organic matter will struggle with water retention. Heavy soils with a high amount of clay, have few pockets for water to travel down into the soil for your plants. In this situation you are better off applying small quantities of water more frequently, giving the water time to absorb into the soil, too much and the water runs off the surface (taking your nutrients with it) or puddles ,which provides a good breeding ground for bacteria. At the other end of the scale, with sandy light soils, water just drains off rapidly, meaning you need to apply large amounts of water but this also means that any nutrient in the soil is draining away as well (leaching). Having plenty of organic material in your soil helps with water and nutrient retention.
Majority of your plants prefer to have a moist soil down at the roots. However there are many that like dry or wet. For example mint, water cress and taro thrive in wet, soggy soils whereas thyme, succulents and cacti prefer drier soils. When you buy seeds or plants most will have labels that tell you how wet they like their soil.
You will hear a lot of talk about whether you should be watering morning, night or any time. I've seen people adamant that you only water mornings, others nights, others any time. Plants are fairly tolerant of when and how they get their water and will usually perform regardless of your methods. I've grown up in a climate that has 200-400ml rain a year, hot summers and water restrictions. For us, watering in the early morning and later in the evening works well. Most don't like to water at night because putting your plants to bed with wet leaves and feet do leave them open for bacterial infections or rot. However in our dry climate this isn't an issue (It may be in more humid places). Watering for us during the heat of the day is a waste of time and money as the evaporation rate is incredibly high and so it provides little benefit to the plants. Morning is a good time wherever you are in the country as it gives the plants a good start to the day and leaves plenty of time for the leaves and soil surface to dry out before night time.
The neat thing about plants is that they can adjust their metabolic activity to help conserve water or protect from drought. They do this by closing up the little pores under their leaves called stomata. This is where they exchange CO2 and O2 and have water loss. Often plants will close these up to conserve water and start again when it cools and there is less evaporation. In extreme heats, some plants will close up their entire leaf. Last summer the air was so hot and dry, our pumpkin plants actually closed up all their leaves and looked incredibly sad from about 11am each day. However by 9pm they would open up and look like normal healthy plants. We had a great crop of pumpkins last year. Your plants will suffer more if you over-water them, because this can deprive them of oxygen in the soil and create anaerobic conditions. These conditions a prone to rot and bacteria.
At the end of the day, it's not going to cause the plants much harm if you just water when you get the chance. Just check your soil before you water to make sure its actually needed. If you are unsure, it's a good idea to talk to people in your area with the beautiful gardens as they would have been growing in you local climate for years or talk to someone at the local garden center.12 August 2022