British Columbia: Fertilize Portuguese laurels now or wait til spring? (red and yellow leaves)

Discussion in 'Outdoor Gardening in the Pacific Northwest' started by Nate Day, Oct 28, 2022.

  1. Nate Day

    Nate Day Member

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    Hello.

    I'm on southern Vancouver Island and planted Portuguese Laurels 3 years ago. While they are doing okay, many of the trees have yellow leaves, and a few trees have a branch where every leaf is dark red (see photo attached). The copious amounts of rain we received last winter and spring didn't make a difference in the yellowing of the leaves, and the soil analysis shows shows "low" or "very low" amounts of NO3-N, pH, T.P., and K. I have a few questions...

    1. Opinions on what's causing the dark red leaves on an entire branch?

    2. Given the lab results, it looks like I need fertilizer but I've never used applied it. Any thoughts on which type to use, and whether I should apply it in the coming weeks as the rainy season begins, or wait until the spring? I've received conflicting advice on fall versus spring; and I've been suggested everything from bone meal and mulch, to 10-10-10 or 20-20-20, to a liquid "rootbooster" product.

    Thanks in advance for any input.
     

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  2. Margot

    Margot Generous Contributor 10 Years

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    The dark red leaves look dead to me - are they pliable or brittle? Either way, I think the branch should be pruned off.

    Was your soil test done by a certified laboratory or with a soil test kit? It surprises me that phosphorus would be deficient in Victoria.

    I would wait until early spring 2023 to apply a balanced fertilizer. NPK (Nitrogen, Phosphorus and Potassium) 10-10-10 or 20-20-20 with micronutrients would be a good choice. Apply according to directions on the container - avoid the temptation to give more. If the new growth looks good, wait until after blooming in 2024 to fertilize again.

    pH is not something like nitrogen that you have a 'low' amount of. It is a measure of how acid or alkaline the soil is. A low pH indicates an acid soil - Portuguese Laurels are said to need a slightly acid to a very alkaline soil so perhaps sprinkling a little dolomite lime at the base would help raise the pH somewhat. Again, apply sparingly.

    Although bonemeal is usually unnecessary in home gardens, it may help address the low phosphorus a raise the pH. Keep in mind that bone meal is very slow acting.

    It looks like you have a nice pine needle? mulch under the laurels and are keeping them watered so, continuing with that and giving them some fertilizer in the spring should ensure their ongoing happiness.
     
  3. Ron B

    Ron B Paragon of Plants 10 Years

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    The branches below the reddening can be seen to have missing bark. Buy and use a fertilizer product packaged for evergreen plants with naming like Evergreen Food or Rhododendron & Azalea Food. The soil test result showing deficiency of multiple different nutrients is abnormal - did you do something at planting like replacing the existing soil with peat or a soilless potting medium? Otherwise pH and nutrients of natural soils throughout the Salish Sea area would be expected to be suitable for this plant much, if not most of the time - it is actually a weed on treed sites in and around local towns and cities. Along with English holly, English laurel, spurge laurel, stranvaesia, Himalayan blackberry, Irish (Atlantic) ivy and so on.
     
  4. Margot

    Margot Generous Contributor 10 Years

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    Ouch. There are many good reasons people enjoy growing Portuguese Laurel even though you and I may not value them so much.

    I was suspicious of the test results too but, you are right to question the soil tested as well as the accuracy of the test itself.

    Since Rhododendron & Azalea Fertilizer supports a lower pH, perhaps it is not the best choice for PL which is (so I've read) better with a higher pH.
     
    Last edited: Oct 28, 2022
  5. Ron B

    Ron B Paragon of Plants 10 Years

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    Portugal laurel growing spontaneously in our region on numbers of sites would seem to argue against it being limited by acidic soils. Otherwise due to the onset of acidic precipitation it has been stated in the past that even rhododendrons and azaleas can benefit from applications of dolomite in local gardens. Note that this recommendation was for use of dolomite and not hydrated lime. And that there was a period some years ago where the Rhododendron Botanical Garden in Federal Way, Washington was displaying a large percentage of rhododendrons with glaringly yellow leaves. With an explanation I was given being that a fertilizer product intended for deciduous shrubs ("lilac fertilizer") and having an alkaline pH had unwittingly been used there. As for bone meal see below under Petrifying Phosphate.

    Garden potions and notions to avoid – The Garden Professors™
     
    Last edited: Oct 29, 2022
  6. Nate Day

    Nate Day Member

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    Thanks for the responses, all very helpful. I did not change the soil before planting, please see soil analysis results below/attached. Also, you can see a number of photos of the laurels as they are now, as well as soil conditions when planted in 2019 here: Portuguese Laurels

    Thanks again for any input.
     

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