Rhododendrons: Rhodo Care

Discussion in 'Ericaceae (rhododendrons, arbutus, etc.)' started by walldenk, Sep 15, 2008.

  1. walldenk

    walldenk Member

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    Hello,
    I was trying to find a web site re the care of rhodos as the leaves on mine are turning yellow. Does anyone have any suggestions re what might be the cause of the yellowing or a website that I might explore.
    Any suggestions will be most welcome. Thank you.
    Kathleen.
     
  2. Wolvie150

    Wolvie150 Active Member

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    Fundamentals of Rhododendron & Azalea Culture might help with good general introduction from varieties to planting, maintenance, and propagation.
    I do know that lower light (than it's normal amount) and low acidity will cause the flowers to fade - have you fertilized with an acidic one in the last month or so? (1-2 weeks if a pot). Pictures might help to show health of rest of plant, comparison of petal colors, etc.

    Another good, across the board reference is the site: The Garden Helper. Seems to be a nice mix of educated amateurs to very educated members, or referenced text that is or has several references listed in it's bibliography.
     
  3. walldenk

    walldenk Member

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    Many thanks. I'll check out both of your suggestions. The leaves are turning yellow and dropping off but I haven't fertilized it recently as I had read somewhere not to fertilize after the end of June. I used just a general azalea/rhodo commercial brand.
    Kathleen.
     
  4. Ron B

    Ron B Paragon of Plants 10 Years

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    Broad-leaved evergreens often shed spent leaves during summer. However, shrub should not be drooping or becoming thin-looking (sparse). Two things often missed in this region are the need of rhododendrons for liberal summer irrigation on most soils here, and the prevalence of a foliage mildew that causes leaves to die and drop prematurely, resulting in gaunt or even dead shrubs after a period of years. This mildew has become ubiquitous in my area, resulting in most specimens inspected showing some level of infestation. Blotching on the upper side of the leaves with corresponding dusty looking areas beneath are typical with plants manifesting that level of infestation. When examined closely the dustiness can be seen to be a fungal growth. Most severely affected types defoliate completely and die.
     
  5. walldenk

    walldenk Member

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    Thanks, I'll inspect the leaves more closely now that I know what to look for. I'd hate to lose the rhodo as I moved it from my Mum's garden after she passed away (28 years ago) so I have an emotional attachment to it.
     
  6. Wolvie150

    Wolvie150 Active Member

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    Good luck. just a quick FYI on the fertilizer: as a general rule, to 'non-gardener' plant enjoys, it is easier to say don't or do fertilize during these times. This is generally the most and least needed times. However, after that much experience, I would say fertilize as you see fit to help with growth/regrowth, just remember to increase watering a bit during the warmer months for the increased metabolism.
    I'm guessing it's not a container with that age (or a lot or work re-potting!), so buildup of fertilizing salts should not be much of a problem. Check mulch and compost levels, that will help. Mulch can be a bugger for keeping TOO much moisture, leading to increased mold/mildew spores and greater chance of plant infection.
     
  7. walldenk

    walldenk Member

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    Thank you for the info. I appreciate it.
    Kathleen.
     
  8. Ron B

    Ron B Paragon of Plants 10 Years

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    Sampling and testing soil is used to monitor fertilizer needs. Otherwise you are shooting blind.
     
  9. walldenk

    walldenk Member

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    Thanks, Ron. I've seen testing kits at nurseries so I'll get one of those.
    Maybe next spring I'll be able to post that my rhodo is looking marvelous.
    Kathleen.
     
  10. Ron B

    Ron B Paragon of Plants 10 Years

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    Better to have a lab do it. Down here it can be ordered through the Cooperative Extension network, don't know what is available up there.

    Fall fertilizing of hardy plants is fine. If the plant needs something it won't benefit from waiting additional months for it.
     

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