Rhododendrons: Problem with old rhododendrom plant

Discussion in 'Ericaceae (rhododendrons, arbutus, etc.)' started by tinam, May 31, 2008.

  1. tinam

    tinam Member

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    ridgewood, nj
    My rhododendrum plant is about 20 ft tall and about 35 ft wide it has not bloomed since we bought the house. The plant is said to be 75-100 years old. It had about 15 flowers last year and none this year. How do I prune it and help it to flower again. It also has spots on it with holes on its leaves. The local nursury said it was fungus and a tree service company said it was a bug attacking the tree so I do not know how to treat my plant.
     
  2. joclyn

    joclyn Rising Contributor

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    can you post some pics? of the whole bush as well as come close-ups of the leaves with the holes in them.
     
  3. Ron B

    Ron B Paragon of Plants 10 Years

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    Pruning of the rhododendron is not the answer, these set buds at ends of strongest shoots the year before flowering. Pruning tends to interfere with flowering rather than promote it. If you have been whacking on it already that could be the problem. Otherwise, if it is in heavy shade that may be suppressing flower production, although it takes pretty deep shade to keep a rhododendron from blooming. Another possibility is that it happens to be prone to freezing of the flower buds in your climate. While strange-seeming this does sometimes happen, the rest of the plant being hardy but the flower buds apt to be lost where the climate is just a little too cold for a particular variety.
     
  4. joclyn

    joclyn Rising Contributor

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    zone 6 is not too cold for this bush. although, late frosts can damage the buds causing them to not open, this is not the case this year. the rhody's have been in bloom for weeks now in this zone.

    they are also shade loving bushes, so, too much shade isn't an issue either.

    how long have you been in the house? have you done any pruning of the bush? if so, when was that?

    please post some pics - they really will be helpful in identifying what the issue is!
     
  5. Ron B

    Ron B Paragon of Plants 10 Years

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    Without knowing the specific variety of rhododendron being asked about you have no way of knowing if it is bud-tender in the climate there or not. Rhododendrons in western cultivation vary from kinds hurt by the lightest frosts to those completely hardy to tens of degrees below 0F.

    Shade tolerance of rhododendrons also varies with the specific kind. And as with temperature there are different degrees of shade. The fact that most tend to prefer some shade in bright climates does not mean that there is no limit to how much shade a given plant will grow in without its development and behavior being affected.

    Where the summer climate is relentlessly cloudy even big-leaved rhododendrons can be seeing growing in the open, in the closest equivalent to full sun.
     
  6. joclyn

    joclyn Rising Contributor

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    one of the reasons i asked for a picture, ron.

    rhododendrum naturally live in shaded woodland areas...azalea's can take a bit more sun.

    going by the size mentioned, as well as the number of flowers, i'm assuming it's a rhody.

    another question for the tinam: were any trees cut down in the past couple of years?

    if so, going from shade to full sun may be the issue...

    please posts some pics or, if you can't, please describe the conditions of the area - other plants/trees in the general locale as well as water levels...also describe any changes to the property directly as well as on adjoining property. (items added and removed and changes like adding more concrete as well as taking it away).
     
  7. Ron B

    Ron B Paragon of Plants 10 Years

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    If you've been there only a few years - you don't say when you bought the house - you may also just be seeing natural variations in flower production from one crop to the next. A heavy flowering one year may cause light flowering to occur for more than one subsequent flowering period. Each specimen has only so much energy, putting out a big effort one year may cause it to take a little vacation for awhile - especially where a massive flowering is followed by a heavy seed crop.

    Just the fact that flower buds are set at the ends of the most vigorous shoots results in that part of the plant perhaps not flowering the following year. After a strong shoot sets and opens a flower bud as many as several smaller shoots come from around the base of the flower bud to continue the growth of the branch. Often most of these aren't big enough to flower themselves the next year and so that particular branch tip may not bloom again for a year or two.
     
  8. chimera

    chimera Well-Known Member 10 Years

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    A good bark mulch extending beyond the dripline may help replenish soil and keep it moist. It may be too dry, especially when trying to set flower buds after forming new growth.
     
    Last edited: Jun 2, 2008
  9. Loulou

    Loulou Member

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    Hello Tinam
    Just curious - what happened with your old rhodo? Do you now have the ability to send pictures? My reason for asking is that I also have some problems with an old rhodo.
     

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