Rhododendrun dropping leaves

aerides(z6 Manhattan)July 26, 2012

I've recently inherited a mature rhodie that grows against the house facing east/southeast. It's shaded by tall trees in my front yard on the other side of a narrow clearing so I doubt it gets much direct sun. It's been there for years and according to the prior owner it blooms reliably.

I've noticed recently is that it is sloughing a lot of lower leaves which turn yellow and drop. Is that normal behavior for a rhodie in hot dry weather? I also cleared out a lot of dead wood from the interior. My gardening friend is recommending that I fertilize it with Hollytone but I'm holding off because fertilizing a stressed plant doesn't seem like a good idea to me. I can improve the mulch though, and I can give it a good water every week. Will this help it? Should I fertilize? Barbara Damrosch of Garden Primer fame recommends liquid fertilizer in spring and fall (she doesn't say anything about mid-summer). I'd appreciate a product recommendation too. How about mixing up a couple of gallons of half-strength fertilizer solution and pouring it directly around the plant? Thanks so much. I want to do all I can for it.

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morz8(Washington Coast Z8b)

Yellowing, then dropping of oldest leaves is normal for rhododendrons, a natural part of the yearly growth cycle. Most evergreens will naturally drop their older needles or leaves (closest to the trunk) after a number of years, making the term "evergreen" plant misleading :) Leaf drop usually occurs in the summer or early fall when the leaves are approx three years old. This period of leaf drop occurs following the maturing of the current season's growth - it's nothing for you to be concerned about.

Improving the mulch is a great idea, will help to conserve moisture and keep roots cool. You're right to water during the dry periods too. Those two things are really all you need to do if the dropping leaves were the only symptom concerning you.

    Bookmark   July 26, 2012 at 10:47AM
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aerides(z6 Manhattan)

Thanks so much for the reassurance. Yes, otherwise it seems happy.

    Bookmark   July 27, 2012 at 9:39PM
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I am wondering if any of my rhododendrons will ever bloom. It is almost October and some of my plants have big buds that are trying to open? Are these just leaf buds? Both of these (english roseum species) did not bloom this spring, otherwise they look very healthy. Any thoughts on why they are behaving so weird? If these buds are trying to open now, the couldn't possibly bloom in the spring right? Thanks for any help you might be able to give me.

    Bookmark   September 27, 2012 at 3:47PM
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They are flower buds, but it's not clear if they are about to open - the kind of "fringe" at the apex of the buds does not necessarily mean bloom is imminent. If they do, you are correct that it will mean no bloom next spring from those that open.

Some rhododendrons - lots of red flowered ones especially - are prone to incomplete fall bloom. This tends to happen when a dry spell is followed by a wet one late in the summer. English Roseum is not, as far as I know, prone to this behavior. The very early spring and other weather oddities in many parts of the country may account for what's happening if they do indeed bloom.

    Bookmark   September 28, 2012 at 5:48AM
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Thank You so much for responding to my post. We have had an extreme dry period of about 3 months. It's the oddest thing, I have two of these english roseums planted about 15 feet from one another. One looks like its buds are unfolding and the other just as tight as can be. Can "fringing" be caused by any kind of pests?

    Bookmark   October 5, 2012 at 6:30PM
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No pest involvement in the "fringe". Some rhododendron varieties - 'Vulcan' is one - show this on nearly all flower buds. Others only occasionally. I really have no explanation for its appearance on just one English Roseum.

    Bookmark   October 6, 2012 at 6:22AM
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