This article was originally featured in The Guardian.
OK, I’ll admit it, I’m a bit of a data geek. As so much gardening advice is based not on systematically tested ideas, but received wisdom, I find doing a bit of measuring and recording can often reveal some surprising results. One of the simplest methods I have found is timing how long I spent doing different indoor and outdoor gardening tasks and noting how they stack up. While I was pretty sure watering was going to come out top in terms of time investment in the growing season, even I was astonished that 70% of my time spent in the garden was dedicated exclusively to holding a hose. If you are anything like me, finding water-wise ways to irrigate will not only save you an enormous amount of time, but reduce your bills and help the planet, too.
Probably the most straightforward and sustainable way to reduce water usage is to ditch growing in containers in favour of the ground. The huge relative surface area to volume ratio of pots means that they will not only dry out far faster than open ground, but will also be subject to wider temperature fluctuations, which can further exacerbate water loss. This is particularly the case in containers with porous surfaces, like fibre-lined hanging baskets or unglazed terracotta, and the smaller the pot, the more thirsty your plants will be.
A second way to help retain vital moisture around the root zone of your plants is to add an insulating layer of mulch. Crack open a big bag of bark chippings, leaf mould or really any other organic material, spread it in a thick layer over the soil between plants, and it will work not only to seal in water, but help cool their roots. As it breaks down, it will further add nutrients, food for friendly soil microbes, and spongy water-retaining fibres, which all conspire to create the ideal conditions for plant growth.
Ultimately, one of the best ways to reduce your need for irrigation is not about retaining the moisture but knowing when and how to water in the first place. First, ditch this whole little and often approach that you often hear about. Light topical applications will only dampen the surface, which on hot days can evaporate off before it even reaches the plant roots. However, giving everything a really good soak half as often allows the water to percolate much deeper, where it not only gets where it needs to, but will create a reservoir plants can draw on. Studies have shown that this technique also encourages plants to put down deeper roots, which makes them more resilient in dry spells, too.
Finally, although the old idea that watering in the heat of the day can burn plant leaves – because water droplets act like lenses – is of limited merit, it’s still not a good idea to water in the peak of the day. Much of the water will be lost to the air, whereas if you water in the cool of the evening, it has extra time to sink in.
Simple tweaks to what you are already doing will save you time, money, effort and, of course, the age-old battle with un-kinking the hose.
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