What's wrong with my azalea?

Discussion in 'Ericaceae (rhododendrons, arbutus, etc.)' started by nichelle, Aug 3, 2019.

  1. nichelle

    nichelle Active Member

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    This spring, I transplanted this azalea from a pot to the ground. Quite a few leaves are turning yellow with brown edges. Too much water, or too little?

    Thanks for the help!
     

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  2. Ron B

    Ron B Paragon of Plants 10 Years

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    Interveinal chlorosis indicates a problem with minerals in the soil or irrigation water. Did you fertilize it with a chemical fertilizer? Or do you happen to have hard water, for some reason?
     
  3. nichelle

    nichelle Active Member

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    I'm in Vancouver, and I water with tap water, so I doubt the water is particularly hard. And I did not fertilize at all, just mixed in some compost when I planted it. Can I do anything to correct this?
     
  4. Sulev

    Sulev Active Member

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    Azaleas don't like hot (avoid planting into spots with direct sunlight at noon). They like temperatures between +10º...+16ºC and humid, but moving air.
    Soil should be acidic (pH around 5), rich of organics, well drained and aerated, constantly moist, but not soaked. Watering should be done with warm (ca +20ºC) and soft water (water with low calcium content - rain water; snow melting water; water. that has been used in freshwater aquarium; water, that has been boiled and cooled to the room temperature, etc).
    Don't plant too deep, azalea's roots like to be near to the ground level.
     
  5. nichelle

    nichelle Active Member

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    Thanks, I'l try all that.
     
  6. Ron B

    Ron B Paragon of Plants 10 Years

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    Planting site being hot isn't going to make it chlorotic. No need to use special water if your tap water is not hard. Probably the thing to look at is what might have been in the bagged(?) product you mixed in when planting.
     
  7. Sulev

    Sulev Active Member

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    Too hot conditions will cause yellowing azaleas leaves. I can't describe, what is difference in yellowing process compared with typical chlorosis, but the result will be pretty similar - yellow leaves with browns spots.
     
  8. Margot

    Margot Well-Known Member

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    Your shrub looks more like a rhododendron to me than an azalea (though, technically, azaleas are rhododendrons). To my eye, it looks perfectly healthy. Rhodos often lose their older leaves at this time of the year so it could be what you're worried about is normal - perhaps more pronounced this year because it was recently transplanted.

    Unless the rhodo is in more sun than it was up until this year, I wouldn't think bright sun, even at noon, is necessarily a problem especially this year when we haven't yet experienced significant heat. Quite a number of rhodos are adapted to full sun growing conditions. The new leaves produced this year look great.

    It could be that because it is no longer in a pot, water is not reaching all the roots. I would give it a thorough soaking - depending on your soil conditions, perhaps an hour of a slow spray from the hose over the root zone - and then try to ensure that it does not dry out until autumn rain takes over. A good mulch would help conserve the moisture in the soil and moderate the soil temperature.

    I have a feeling that this time next year, your rhodo will have settled in, looking better than ever.
     
  9. Sulev

    Sulev Active Member

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    My rhododendrons (at 59.3 N lattitude) have no single yellow leaf so early in August.
    Rhodos (and Azaleas) have so shallow root system, it is hard to imagine, how water may not reach roots, when watered regularily.
    If to mulch rhodos, then better be it well aerated mulch. I keep turf away from my rhodos crown area, to ensure, that the soil is well aerated.
     
  10. Margot

    Margot Well-Known Member

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    We have to keep in mind how soil, growing conditions and plant size can vary enormously from garden to garden.

    My suggestion that Nichelle's rhodo might not be getting water to all the roots is based on my own experience growing rhodos in pots where the volume of soil is about 1 cubic foot. With anything growing in a pot, it is very easy to make sure that the roots get plenty of water - but - put those same plants in the ground, it can be a different story.

    Where I live, water delivered by the irrigation system does not penetrate the garden soil very far down at all. Even a few inches below the surface, it is bone dry. My theory is that, in the garden, rhodos and other plants develop a wide enough root system to take advantage of whatever water they can; something that wouldn't benefit a newly planted rhodo until it has time to grow roots more widely. There may be mycorrhizal assistance as well in the garden at large. I mainly use leaf mulch because it is readily available.

    Even so, the older leaves on a few of my rhodos began to turn yellow at the end of July - perhaps a sign of stress that it's happening this early.
     
  11. nichelle

    nichelle Active Member

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    Thanks for the comments and suggestions! I'll try deep watering, but maybe there's really nothing very wrong with the plant.
     
  12. Sulev

    Sulev Active Member

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    You should still check first, if the soil is dry or moist, before you undertake some radical changes in your watering habits. If your soil is heavy (clayish), then too much water can easily kill your Azaleas.
    Dig a small hole near the border of the crown area, up to 40 cm deep, and you will have a good overview, how well your previous watering habit has worked.
     

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