Yellow Leaves on Rhody, why?

LindaMA(MA z5)September 4, 2010

Does anyone know what causes the leaves on a rhody to turn yellow and then drop off the bush. I have two new this spring, big leaf rhody's that this keeps happening too, one a lot more than the other.

One is a 'Catawbiense Album' and the other is an English Roseum. They both appear to be healthy with the exception of the yellow leaves. The English Roseum already has a good amount of buds established on it but the other, not that many. I'm worried that if the leaves keep turning yellow and fall off that eventually my rhodys will look terrible. On some of the leaves which turn yellow, there are also green spots in the yellow portion and sometimes brown.

My soil is acidic and tends to be very claylike but I have amended around the shrub well before planting them.

I have two PJM elites panted on the opposite side of the front of the house and they are doing well. I also have a (name escapes me at the present time) small rhody that is very much like the PJM elites, only the flowers are a very pretty pink color, rather than a lavendar.

Any thoughts or suggestions are greatly appreciate.

Linda

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morz8(Washington Coast Z8b)

Linda, are the leaves that are dropping the innermost and lowest leaves on stems? If so, that's normal for this time of year....leaves approx three years old will turn yellow, orange, even red and then drop.

If you are losing leaves from this years or last years growth or if those upper and outer leaves look off color to you...let us know and we'll look another direction.

    Bookmark   September 4, 2010 at 6:49PM
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LindaMA(MA z5)

Well most of the yellowing and falling off is on the bottom, although now I'm seeing it in the middle of the shrub. If they were just yellow leaves I'd say that's normal but is it normal for the yellow leaves to have black spots, green spots and brown spots? I know I don't have the best soil, and in the bed where this particular rhody is planted, the soil is horrible. I do keep amending it though, only wish I could get down deeper into the soil around the rhody but I can't.

This rhody is also near a very large oak tree with roots going everywhere, I'm wondering if some small roots are disturbing the area.

Oh well, hopefully the yellowing leaves falling off are normal. I'm not as concerned about the other rhody, it's on the opposite side of the house and the other smaller rhodys are doing well.

Is there a good fertilizer that I could be using? I have a bag of Lobster Compost that I can top of the area around the rhody, do you think this will help?

Thank you for responding, I really appreciate it!

Linda

    Bookmark   September 6, 2010 at 9:05AM
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morz8(Washington Coast Z8b)

Oak are generally not surface rooted and aren't thought to offer much competition for rhododendrons and azaleas - they are one of the first trees of choice for underplanting with these shrubs. Lobster compost isn't available here, in checking it appears to have a ph of approximately 6.5 - 6.8 so while not especially acidic, not completely out of the range for healthy rhododendrons either. I have a clay based soil too, top dressing with compost in Spring, repeating in Fall has helped to condition/improve the soil over the years and the practice has the added benefit of my not requiring additional fertilizer - my shrubs have never shown any symptoms of needing it.

Rhododendrons and azaleas have low nutritional requirements compared to many shrubs, when grown in soil of the correct ph they may never need supplemental fertilizer. When fertilizer is required (and it's late in the season to be considering fertilizer in your zone), the one most often recommended here is Hollytone.

    Bookmark   September 6, 2010 at 10:24PM
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LindaMA(MA z5)

Thank you very much, I really appreciate your input, I will keep a watch on them and hopefully they will be okay come spring. I did notice black spots on a couple of leaves when I was out in the yard doing some fall clean up yesterday, hopefully this isn't anything to worry about.

Linda

    Bookmark   September 7, 2010 at 11:31AM
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teabag43

I have leaves turning yellow and dropping off at the bottom of the plant every year. The trouble is sooner or later the plants start to look leggy with the leaves in clusters at the top. I got fed up with one plant and just chopped it right back. Well it came back to life and was back blooming this summer. Now the bottom leaves on it are turning yellow as well. I suppose that being a northern garden is part of the problem but I would really like my plants to not bare their lower stems. Anyone know how?

    Bookmark   September 22, 2010 at 4:36PM
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rhodyman(SE PA, USDA Z6)

Too much shade makes plants grow tall and gangly and loose their bottom leaves. More sun makes the plant more compact and healthier looking. If you have some plants/trees giving this area shade, the best thing you can do is to remove the lower limbs so the shade is higher and less dense.

If the shade is too dense, severe pruning can actually kill the plant rather than revitalize it. So you shade must not be extremely dense.

Here is a link that might be useful: How to care for rhododendrons

    Bookmark   September 28, 2010 at 5:36PM
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linkatt

Because it needs acid fertilizer like holly tone.

    Bookmark   May 3, 2013 at 6:52PM
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