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Well, does it? If you adhere to the common advice from WiseGEEK then we must answer in the affirmative.
The most common response to this question is: Plants should be watered in the morning to avoid fungal root diseases.
The logic plays out like this - if you water your plants in the morning then they will have time to dry out before nightfall. For at evening, once the sun has set, plants are unable to deal with water around their roots and become susceptible to all manner of fungal diseases. Really?
Let's chew through this one a little more before we swallow it hollus-bollus.
Now, if this were a true statement then shouldn't we be covering our plants when it rains during the night? And how many of us gardeners have had plants wilt and die from fungal root diseases after enduring months of rainy days and evenings? I'll hazard a guess at none.
So, why should this argument have any credibility at all? Maybe it has to do with the temperature increase during watering periods. As with food, if it's held at temperatures above 5°C and below 60°C you're more likely to increase the risk of food spoilage. Perhaps the problems occur because we mainly water during our warmer months.
The problem with that argument is that these would increase bacterial disease - caused by bad hygiene practices - but have no affect on fungal diseases. Fungal diseases are usually a result of damp conditions.
If we've already dismissed that the time of day has little effect on damp conditions then there must be a culprit lurking in the corner. Let's pull him out...[drum roll, please].
And the malefactor is not the time of watering but is instead - poor drainage.
Poor drainage can kill your plants quicker than a dose of glyphosate. Most plants don't enjoy wet feet and would rather take their nutrients as quickly as possible and then be released from the burden of sitting in a 'cold bath'.
This is why gardeners need to improve their soils. If they're sandy and drain too fast then the plants will not be able to source enough nutrient and you will need to water more often. Those gardeners who suffer from clay soils will find that they don't drain as readily. Find a balance between the two and suddenly you will have plants singing your praises and performing beautifully.
If you're looking for some answers to improve your soil read on here...
Gardeners who accuse the time of watering for their plant failures have inappropriately blamed the wrong source. It has nothing to do with the time of day you water merely how well the soil drains around your plant roots.
If your plants have good drainage then enjoy the liberty of watering either first thing in the morning or last thing at night.
Comments
Another issue is that plants are living creatures and they breath through their roots so water logged roots mean that they literally drown in water logged soils.
Even mangroves have roots they keep above the sea water levels in order to survive.
Another issue they don't take into account is plant burning in climates like in Aus, where water left on plants can literally act like a magnifying glass and or literally get high enough in temps during summer to cook plants.
Posted by: Bare Bones Gardener | October 23, 2007 1:31 PM
I absolutely agree with your thoughts on watering. I do my watering either in the morning or in the evening--depending on my personal energy and my work schedule. The garden and I are very comfortable with things this way.
Posted by: mary t | October 23, 2007 8:13 PM
I never believed the idea that watering in the evening was so bad. Like you said, it rains in the evening and at night so .... Also, I don't get up early -- for anything -- so it's much more convenient to water in the evening after work than first thing in the AM. Right now we're working on another 2+" after the 15" we had last Thursday. Wish I could send some of this to the California wildfires.
Posted by: Jenn | October 23, 2007 9:02 PM
Thanks for your comments Jenn, Mary and Bare Bones. It seems that the argument for not watering at night is largely theoretical and points the finger at the wrong problem. Anecdotal evidence such as yours appears to be the norm thereby refuting the debate.
Posted by: Stuart | October 24, 2007 8:43 AM
Hi Stuart,
Sorry I haven't been over to visit much lately. Busy, busy, all the time it seems.
I've often pondered on the same thought about watering..(If it rains at night, then....huh?). I water whenever it's convenient too, and more often than not that's in the evening. I think you've hit the nail on the head here.
Posted by: kerri | October 27, 2007 8:06 AM
Thank you for the watering answer. I always heard not to water in the heat of the day becuase it isn't able to get deep into the soil before it evaporates.
I appreciate the info.
Mary :>)
I hope my gardening info would qualify as a popular interest.
Posted by: Mary | October 28, 2007 4:22 AM
I've always said that there were afternoon/evening thunderstorms long before there were gardens and if afternoon/evening water killed plants then they'd all have died off centuries ago.
Posted by: Sarah | October 28, 2007 8:28 PM
Greetings again from Blithewold in RI, USA - it's been ages (ever?) since I've commented here... My 2 cents, for what it's worth, is that plants use the water during the day for transpiration. It's not that plants are going to DIE if they're watered at night (although it's true that fungi thrive in the damp dark!) but it's not doing them much good either. These days don't we all want to/need to be more mindful about efficient water use?
Posted by: Kris at Blithewold | October 29, 2007 11:25 PM
I didn't water once this summer. The rain did it for me, sometimes in the day, sometimes in the night. This has not always been the case. The Catskill Mountains were soggy the entire time, or soggy enough.
Posted by: John SMG | November 3, 2007 11:13 AM