This Common Watering Mistake Could Be Killing Your Garden

I'm guilty of this. Are you?
Olga Rolenko via Getty Images

Right now, I’m sat on my kitchen floor (so deliciously cool), sweating over my keyboard and looking at some withered, browning grass outside. We are one, the grass and I.

OK, maybe that’s a little OTT. But my point stands: whether you’re a plant or a person, it is officially too bloody hot right now.

If you’ve got so much as a balcony box, you might have noticed that some blooms are struggling to thrive in this heatwave. And while it makes sense to water them in response, it turns out most of us are getting our gardening wrong around this time of year.

Dr Brett Summerell, The Royal Botanic Gardens’ chief botanist, told The Guardian that when you water your plants matters just as much as how often and where you do it.

We need to “bust that myth around watering in the middle of the day,” he said.

So, why does it matter when we hydrate our hydrangeas – and what time should we be actually doing it?

You should avoid midday watering at all costs

Well, everything from the soil to the air wants sweet, sweet hydration just as much as your plant does – and they’re not afraid to rob from your roses.

“Watering in the heat of the day is not a good idea as much water is lost through evaporation from the surface of the soil and the plants will use water more efficiently if watered in the cooler parts of the day,” says the Royal Horticultural Society.

It should go without saying that dehydrated plants are at massive risk of wilting and even death.

“If plants run short of water they shut down their stomata and photosynthesis stops and is replaced by photorespiration,” Alastair Culham, associate professor of botany at University of Reading, writes for The Conversation.

“As the water shortage gets more severe, plants will wilt – the beginning of cell collapse. Initially this is temporary wilting and the plant can recover rapidly when water is available. But further drying will cause permanent wilting, which results in the death of parts of the plant – or even all of it.”

OK, so what time *should* I water my plants?

There’s no clear, one-size-fits all answer – though the advice not to water in the peak of summer heat is universal.

It also seems to be a good idea to water your plants before you know a heatwave is coming in order to strengthen the soil. So if you get a weather alert the day before, that night you should get watering – ensuring you give plants lots to drink.

If you want to really ensure they stay hydrated, you could also get up early and water them first thing on the day of said heatwave.

The Royal Horticultural Society makes a strong case for both morning and evening watering. “Water in the mornings, if you can, as this is when the sun comes up and plants will start to use water,” they say. “Evening watering is also fine, as the cooler conditions mean less water is lost to evaporation.”

They share that the signs your plants could do with more watering include lacklustre leaves, a lack of foliage or flowers, wilting, dropping leaves, and pots becoming lighter.

Where you water your plants matters, too

It’s pretty satisfying to pour as much water as possible on your ailing plants when they show signs of dehydration.

But aside from when and how much you hydrate your plants, where you water them matters too.

“Plants can only effectively use water through their roots, taking water from the surrounding soil or compost,” says the Royal Horticultural Society.

“So water needs to get to where it’s needed, at the tip of the roots and not the leaves.”

In fact, applying the water to the leaves instead of the roots could encourage fungal problems and evaporation from the surfaces. Not ideal.

To encourage water penetration, the Royal Horticultural Society says that “watering more thoroughly, but less frequently helps get the water down to the deeper root tips”.

“It is better to water the garden before drought really sets in, to keep the soil moisture levels even and avoid the soil being continuously dry,” they say.

So long as you avoid that water-wicking midday sun...