Help w/ Thuja Occidentalis 'Smaragd' (aka Emerald Green Cedars)

Discussion in 'Gymnosperms (incl. Conifers)' started by ChrisC, Dec 26, 2020.

  1. ChrisC

    ChrisC New Member

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    Hello and happy holidays! I'm looking for a bit of help with a recently planted (three - four days ago) hedge row of 15 emerald cedar trees. I gather this is probably a common topic but I'm new to this and am looking for a bit of advice! Shortly after planting these trees, the tips of the needles have started to yellow - primarily on the very tops of the trees foliage but some down the body of the tree too. The interior and base of the tree has remained green. Is this normal behavior resulting from transplant shock? Should we be concerned? Anything we should be doing in the short term to help them along? We are worried because they were very green in their pots and only after planting have they changed colour.

    A bit of background:
    -This bed used to have a large (15+ ft) Western Red Cedar hedge that had been over-trimmed on one side and lost all of it's green needles. The hedge was removed and the stumped grinded down ~8 - 12" as we wanted to replace with something a bit smaller that we could be maintained <12 ft high.
    -We replanted with emerald cedars spaced 2 - 2.5 ft apart
    -Due to some of the pre-existing stumps and roots, we probably didn't dig the holes as big as we should have. The holes were probably 1.5x the diameter of the 10 gallon pots that the cedars came in and about the same depth as the pots. The instructions we received from the nursery was that the root ball should sit approximately 1" above surrounding soil once planted.
    -During planting, we added a bit of peat moss to the base of the holes and filled the annulus space around the trees with a loose mix of peat/ native soil mix. We added a handful of bone meal around the surrounding soil and then watered with a bit of root booster, as recommended by the nursery.
    -The two days after we planted were cold with overnight temperatures below 0 degrees Celsius.
    -We have watered them daily to ensure the root ball stays moist.
    -The foliage has started to yellow, especially at the tips and near the top of the trees. Some trees are worse than others but there is definitely a trend across all of the trees.

    Any advice on what might be happening and if there is anything we can or should do about it? They weren't overly pricey but we definitely want them to survive and live long, happy lives.

    Thanks so much!!
     

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  2. Margot

    Margot Generous Contributor 10 Years

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    Hello @ChrisC and welcome to the Forums!

    I am not the most knowledgeable person to be offering you advice but I have planted several hedges over many years so have a few comments.
    1. It is really hard to kill an Emerald Cedar hedge. Despite initial setbacks due to transplant shock, they will almost inevitably recover and thrive.
    2. This is a good time of year in many ways to plant shrubs because they should get all the water they need from our generous rainfall and, at the same time, not be subject to dessicating heat. Once watered in after planting, there should be no need in Victoria for additional water until late March/early April.
    3. We are learning from science that less is more when planting most everything. Forget about ammending the soil, adding bone meal, peat moss, etc. Experts such as Dr. Linda Chalker-Scott (Linda Chalker-Scott | Washington State University) go so far as to advocate washing roots and trimming them if necessary before planting into the soil where they'll be living their lives.
    4. Planting a new hedge so soon after removing a substantial old one presents challenges which are hard to assess. For example, if the 'grindings' of the former hedge are now a big component of the soil you planted the new trees in, it could constitute a drain on available nitrogen and I doubt that adding nitrogen at this cold time of year would counter that.
    5. If this were my hedge and a budget were not an issue, I'd be inclined to remove all the soil that the former hedge was growing in and replace it with a reasonable, not-too-rich, top soil and then replant the new hedge.
     
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  3. ChrisC

    ChrisC New Member

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    Thanks Margot! This was really helpful. They haven’t gotten any worse since I posted so we’ll just wait and see how things go. And we’ll definitely keep point #5 in mind if we are faced with a similar project in the future.
     

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