To Water Or Not To Water In The Sun | Green Patches - Mediterranean Gardening

Saturday, June 23, 2012

To Water Or Not To Water In The Sun

portulaca flowers
My Portulaca Flowers in a Summer Day Before Closing In The Evening

When I first started out gardening, the first advice I got was to never water plants during the day.  It had to be either first thing in the morning, or in the evening.  Unfortunately, these times also happen to be when I am most forgetful so I hate to admit it, but I have broken this rule often for the sake of my plants.  In the summer heat, this piece of advice comes more as an impostion for me, it is the time when the plants needs most water, but it is also the time when I am hardly around to do that.

So why is it bad for plants to water them in direct sunlight?  It was never quite explained to me. This was like a defacto standard around our house when I was young watering my father's plants, no questions asked.  This afternoon as I was trimming down my Plumbago I was tempted to water it, and I remembered this rule.  I decided to do a little search on the net to better understand this.  

It was always my silent understanding that it was bad to water the plants in the sun because the water simply evaporates too quickly.  It did not make much sense, therefore, because the plants would not be getting their full share of water, and more water would be wasted in the process.

Apparently, however, there is another debate going on on the Internet. Two conflicting articles written in 2010, one from the Daily Mail and the other from the Daily Telegraph helped in this confusion.  The Daily Mail claims that the reason it is bad for the plants, researchers found, is that the tiny droplets of water on the leaves of the plants act like a magnifying glass, intesifying the heat, and could also lead to leaf burn.  The Daily Telegraph on the other hand claims that this myth has been 'debunked', and that researchers have proved that this is simply not true.  So I'm back to square one.

Another reason I found online is that the plants open up their pores when they are watered, because they think that it is raining.  Since it is actually scorching hot, this may damage, and burn the plants.  Someone else argued that watering the plants in the morning, or evening allows the water to sit longer in the soil, or plants, which may lead to root rot, or fungus to develop.

As I was thinking about watering my Plumbago this afternoon, a very simple fact made me decide not to.  As I opened the tap to fill up my watering can, I realised that that the water was boiling hot.  I couldn't even touch the first few litres of water until the pipes cleared.  My plants would surely suffer if I gave them that water. If I had to throw away a few litres of water every time to let the cool water run down the tap I would be wasting more water, and money.  

After all this, I came to the conclusion that it all depends on the intensity of the sun.  If it's too hot, don't bother.  Save yourself some sweat, and do it in the evening.  If the plants are just wilted with the heat, but they are actually in a shady spot then I guess it won't do much harm.  In my case, I guess the water is just too hot for them, best to do it when it's cooler.  

What's your opinion?  Feel free to share, as always :)


  1. another guideline I read was - in the midday heat the plants wilt, but overnight they revive. Then they didn't need watering. Quite frankly for the waterer, in the midday heat is too much like hard work!

  2. I like your portulaca! I have two concrete urns in the front garden. I tried several different plants there, which all died in the hot environment. Then I discovered portulaca. They thrived where the others perished. Hooray!

    As for watering: I believe water droplets do magnify the intensity of the hot sun and can scald leaves. At least this has been my experience; it has happened to my plants several times, so I try to water either in the morning or later in the day.

  3. Hi Diana,I totally agree, it's just too hot :)

    Deb, I don't have the Portulaca any more, sadly it died on me a couple of years ago, but I would love to have another one, I couldn't stop looking at those flowers.

  4. I learned the same information. I tend to avoid watering between about 10 a.m. and 2 p.m.--partly because I'm not around during that time anyway, and also because I'd been told the things you mention. But I do water during the morning and the early evening after work. I have also heard that watering at night can increase the risk of plant disease because of water remaining on the foliage. But a way to avoid this is to put a slow drip around the base of the roots so the water doesn't sit on the foliage at all. Of course my climate is a little different than yours, but some of the practices are similar no matter where your garden grows. Great post!

  5. Watering in sun is a tough call. I did today, although I rarely water ever, but we have been experiencing extended times with no rain. The plants were fine, none burnt. Generally though, best to water in early morning.

  6. I try to water in the morning (I've heard watering in the evening can increase fungal disease), but honestly sometimes the only time I am available to water plants is in the afternoon. I'll just go with the theory that some water is better than none.. and I do try to site plants so that they don't need so much water.