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Water on leaves ... or not?

ShepherdsBarnShepherdsBarn Posts: 401
in Plants
I am confused about watering the plants in our polytunnel. I read that some plants are happy to have water on their leaves and others are not. Apparently tomatoes don't like water on their leaves ... but the same plant can be grown outdoors. So what happens when it rains? 🤷🏼‍♀️ Is there a definitive list (or rule) for the plants that do/don't like water on leaves, please?
I am growing ...
tomatoes, cucumber, cucamelon, squash, watermelon, lettuce, pumpkin, courgette and pepper.

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Posts

  • punkdocpunkdoc Posts: 15,039
    I think the problem with water on the leaves, is that in hot sun, drops left by a hose/can can cause the leaves to burn. Obviously not such an issue with rain.
    How can you lie there and think of England
    When you don't even know who's in the team

    S.Yorkshire/Derbyshire border
  • ShepherdsBarnShepherdsBarn Posts: 401
    Ah, thank you ... I will keep an eye and try to water late afternoon/early evening - hopefully they will dry before the sun appears next day ... which actually isn't until late morning due to the overhanging trees. 🙄
  • nick615nick615 Posts: 1,487
    If the number of plants you wish to water isn't prohibitive, there is a way you can avoid getting water on the leaves.  As a gesture to my ageing back I bought a 'walking stick' of 16mm steel from a local blacksmith, as per the illustration above, at a modest cost of €8.  With this, and this is where the number of plants comes in, I dib holes alongside any plant I feel needs water, to a 12 inch depth as marked.  I then fill the holes with water, with or without added feed, so that it arrives exactly where needed below my plants.  I also avoid providing water to any adjacent weeds!  Will last a lifetime.
  • FairygirlFairygirl Posts: 55,117
    When its raining - it isn't usually sunny  :)  
    If you're watering indoors [house, greenhouse, polytunnel] in sunny conditions, the sun's heat is magnified and is more intense, so that can make a difference. It's also less wasteful to water in at the base as the plant gets it where it needs it most. A plant undercover is more at risk anyway from sun because it's easier for foliage to get scorched.

    Lettuce is better without too much sun.  :)
    It's a place where beautiful isn't enough of a word....



    I live in west central Scotland - not where that photo is...
  • Busy-LizzieBusy-Lizzie Posts: 24,043
    Tomatoes outside that get rained on a lot often get blight.
    Dordogne and Norfolk. Clay in Dordogne, sandy in Norfolk.
  • ShepherdsBarnShepherdsBarn Posts: 401
    That's a great idea, @nick615 thank you - we will have a go!
    Thanks @Fairygirl and @Busy-Lizzie for your help.


  • nick615nick615 Posts: 1,487
    ShepherdsBarn  No pic, I'm afraid, but I've since tarted up my dibbers.  My new one uses 20mm tubing which is marginally better so, if you're thinking of getting one, you might consider the larger option?  Good luck.
  • ShepherdsBarnShepherdsBarn Posts: 401
    Thank you! 👍
  • steephillsteephill Posts: 2,841
    The idea that water drops on leaves might burn them is a myth - ye canny beat the laws o' physics. Water droplets do indeed act as lenses but their shape determines the focal length of the lens and therefore the point where it would concentrate enough light to cause burning. In order to work as a magnifying lens capable of scorching leaves it would have to be suspended several millimetres above the lens. In fact it is more likely that water drops on leaves help cool the leaves through evaporation.

    Normal transpiration also gives rise to water drops on leaves, easiest to spot in the morning before it evaporates.
  • ShepherdsBarnShepherdsBarn Posts: 401
    Thank you for your expertise! 😊
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