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Soil Help for Rhodies

limestoner
13 years ago

I need some help. Bear with me cause it might get long, but I will try to keep it short. A couple of years ago I planted three Mountain Laurel in front of my home. It is an inside corner with good protection from the wind and gets morning sun. They did fine the first year. Last year they were alive in spring but only had a couple flowers. By last summers end I had lost two of them. Now the third looks as if it is on its way out. One thing I noticed was the leaves of the new growth from last year appears to be a light lime green color which after some research appears to be iron chlorosis. So, I am about to pull out the third and final mountain laurel. Where do I go from here? My initial thought was to replace them with rhodies. A freind of mine told me not to get the mountain laurel in the first place because he has never had success with them and they are very tempermental. But my initial thought was it is the soil. I do have a clay based soil. Though I did try to follow suggestions to break it up I was very inexperienced at the time and may not have done a great job. Also, I have two purple gem rhodies outgrowing their space just a couple feet from where the ML were, Hostas that I dividing last year because they are growing like mad, thee ferns that are happy as can be, a little hemlock doing very well, three PJM's doing very well and numerous azaelas flourishing all around all in the same soil. So now I am going the other direction and wondering if it is the mountain laurel. I have recently been researching soil recommendations for rhodies and was planning on builing a raised bed where I am going to plant them. So do you think it was the Mountain Laurel or is it the soil? Should I go with a raised bed or not? What is a good soil combo to go with either for the raised bed or just to use for amending the current area? Just so you know I am planning on putting more PJM's in. My wife loves the ones we have both for the flowers and the foiliage. Also I have not had my soil tested. Help me out. I appreciate your advice.

Brian

Comments (7)

  • rhodyman
    13 years ago

    Here is what the extension service says about growing Kalmia latifolia, the native mountain laurel:

    The culture of this plant is relatively exacting. Plants require a well-drained moist acid soil with ample organic matter. Plants do best if grown in part shade. Mountain-laurel has a well deserved reputation of being difficult to establish in a garden/landscape setting. Amending the planting hole soil (backfill) with organic matter increases transplant success. Another recommendation to increase transplant success is to dig the hole only half as deep as the soil ball and then place the plant into the hole and cover protruding root ball with a highly organic soil. If you have clay soil, then you might consider constructing a raised bed to grow this species.

  • mainegrower
    13 years ago

    In my experience mountain laurels are definitely more difficult to grow than rhododendrons, especially in the first few years after planting. They will die for no readily apparent reason. Mountain laurels do demand even better drainage and more oxygen at the roots than rhododendrons - both objectives are achieved by planting above the soil and using a very coarse planting medium. Your clay soil may offer an explanation for the deaths of your laurels.

    Since the rhododendrons are doing well, lack of acidity is not likely to have been the problem. If the mountain laurels were planted in a good deal of sun, the condition of the leaves might have been the result of lacebugs. The damage can look very similar to chlorosis. Lacebugs will infest Purple Gem and to a lesser degree PJM, but they do less damage and less obvious damage on the thicker leaves of the two rhodendron varieties.

    Hope this might help.

  • limestoner
    Original Author
    13 years ago

    Thanks for the input. So, I am thinking to give it a go given the success of the other rhodies in the area. But to hedge my bets I am still going to do a little bit of a raised bed. Anyone have a good recommendation of what type of soil to use or mix with the existing soil. I know you say organic matter but how does that translate into products that I can purchase at my local nursery. I have heard fine pine bark nuggets, pine needles, peat moss, etc. mentioned to be used to amend the soil or is there a good pre-mixed product that can be purchased. Thanks everyone.

  • mainegrower
    13 years ago

    All of the amendments you mention will work except peat moss and pine needles. Once the peat dries out it will repel water and its dust like consistency does not supply enough air space. Pine needles make excellent mulch on the surface and might be added in small amounts, but have problems as an amendment unless they've started to break down.

    My favorite is partly decayed softwood bark either alone or mixed with the smallest bark nuggets (or very coarse sand or Turface) to ensure a lot of air space. You don't need to mix this with the soil. Just plant into it on top.

  • rhodyman
    13 years ago

    Peat moss is a popular amendment because it acidifies the soil and help regulate the moisture. As mainegrower mentions, it is hard to get wet once it dries out. That is seldom a problem if thoroughly mixed with the soil and some other material like pearlite or vermiculite and completely covered with a good mulch. I like pine bark nuggets as my mulch. Rhododendrons like them also. Their roots tend to grow up into the nuggets.

    Another good soil amendment is made by Frey Brothers in Quarryville, PA. It comes bagged as Twin Oaks Organic Pine/Soil Conditioner. They sell it as a mulch or soil conditioner. We grow on rooted cuttings in it straight. They love it.

    Here is a link that might be useful: Frey Brothers Bagged Mulch

  • limestoner
    Original Author
    13 years ago

    You are all very helpful. I appreciate it. One more question is there anything I can add to help break up the clay or should I not even worry about it?

  • rhodyman
    13 years ago

    Yes, gypsum breaks up clay if it is worked into it. But you may just form a clay tub with good gypsum treated clay in it. Since clay has poor drainage, it will drown plants like rhododendrons that are planted in the good soil in this tub. They is why a raised bed is the best solution.

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