Hedges: Can this cedar hedge be saved?

Discussion in 'Gymnosperms (incl. Conifers)' started by botanicalnewbie, Mar 14, 2015.

  1. botanicalnewbie

    botanicalnewbie New Member

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    We recently moved into a house that has a severely neglected cedar hedge. The hedge is about 20ft high and about 30 ft wide. As I know next to nothing about cedar hedges I'd love some help. The hedge is looking pretty sad, large branches are leaning out of the hedge, large brown areas, lots of seeds. I don't know if the hedge is salvable or not. Will trimming it and cutting it shorter encourage it to fill out? I was thinking getting some nutrient rich soil would help as well as fertilizing but honestly didn’t know if the trees were too far gone to save. I’ve attached a picture of the hedge.

    I live in the interior of British Columbia so it's not nearly as wet as the coast. For some reason my pictures attached upside down. No idea why.

    Thanks for the help.
     

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  2. Ron B

    Ron B Paragon of Plants 10 Years

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    Yes, possibly mulching and watering would produce an improvement. Thuja occidentalis is an eastern North American species, coming from a region with rainy summers where it often occurs in wetlands.
     
  3. Sundrop

    Sundrop Well-Known Member

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    You could tie up the big branch back to the tree using a soft rope (old pantyhose would be perfect).

    Okanagan is rather dry during the summer, so deep, infrequent (say every 10 days) watering of this moisture loving species during dry spells is a good idea. Make sure that the soil will get moist at least 1 to 1 ½ m. deep. On average, 1 inch of water will penetrate the soil 1 foot deep. Check your soil to adjust this amount to your particular circumstances. Frequent, shallow watering leads to shallow root development resulting in a variety of future problems.
    Mulching trees will lead to the development of a shallow root system as well.

    So, deep watering - yes, shallow watering, mulching and adding nutrient rich soil on top – no.
    If you decide to fertilize, make sure that nutrients will go deep into the soil, as well.

    As for pruning Thuja I don't have any personal experience, so can't give you any advice. From what I can see everywhere around I would say Thujas are for pruning ;-), but it may be different with such old ones.
     
  4. Ron B

    Ron B Paragon of Plants 10 Years

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    Mulching pretty much always produces a marked improvement, except perhaps for a situation such as the attempted cultivation of warm season vegetables in cool climates. The old soak-and-dry watering recommendation is a myth, feeder roots are concentrated near the surface - where the air is - regardless of how often the soil is moistened. Allowing the soil to dry significantly and then flooding it in alternation over and over through the season produces a situation that would be completely abnormal in nature in humid climates or otherwise moist sites, resulting in a detrimental condition for small roots.
     
  5. Sundrop

    Sundrop Well-Known Member

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    To answer just a fragment of one sentence above "feeder roots are concentrated near the surface":

    Here http://www.motherearthnews.com/organic-gardening/root-development-vegetable-crops-zb0z1308zkin.aspx is a scientific study showing how roots (feeder and otherwise) of even small plants, like vegetable crops, will look like in normal growing conditions.
    The scientist, John E. Weaver, and his team dug trenches 5 feet deep to study the root systems of commonly grown vegetable varieties. Even the roots of small plants like Spinach, Peppers, Onions, to name just a few, will go as deep as 3 ft. or more in search for moisture and nutrients. 3-5 months old Beet roots will go as deep as 10 ft.
    Based on this, without even looking for the results of scientific research, it would be simply against logic and against the laws of Nature to expect that tree roots will remain, in normal conditions, in the ½ ft. deep, closest to the surface layer of soil.
     
  6. Ron B

    Ron B Paragon of Plants 10 Years

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    Vegetable plants are not trees and shrubs that are organized to function over a period of many years on a variety of soils, frequently in humid regions where oxygen levels fall off rapidly as the immediate vicinity of the surface is left. That the majority of tree roots outside of arid regions occur in a mat or pancake near the surface of the soil is a widely known and reported fact that can be seen on this side of the mountains perhaps most dramatically every time a forest giant topples, to reveal an amazing board flat flat bottom to its quite shallow root system - that reflects where the apparently essentially airless lower level of soil was encountered.
     
  7. Sundrop

    Sundrop Well-Known Member

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    It would be nice, sir, if you supported whatever you want to say by the results of scientific research.

    I do agree with you on one point, id est "Vegetable plants are not trees and shrubs".

    Otherwise, here is a scientific study on the root development of Apple trees (I hope you will agree with me that Apple trees are trees) http://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=1912&context=extensionhist :
    "The development of root systems was extremely rapid, the roots reaching a maximum depth of 8.8 and a lateral spread of 12 feet the first year, and 14.8 feet and 21.2 feet the second. During the third year the maximum lateral spread reached 29.4 feet and the maximum depth reached was 17 feet. This greatly exceeded the lateral spread of three-year-old tops, which was about 6 feet, and the height of the trees, which was 7 to 8 feet. "
    and
    "The root systems responded readily to changes in soil environment. Under clean culture a generalized root system was produced. The roots penetrated deeply and spread widely in such a manner that a very large volume of soil was thoroughly occupied. . . . Under straw mulch the roots had a pronounced shallow, lateral development. Under sod mulch both tops and roots were dwarfed."
     
  8. Daniel Mosquin

    Daniel Mosquin Esteemed Contributor UBC Botanical Garden Forums Administrator Forums Moderator 10 Years

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    Quite a bit of information on the topic in this report:

    The Influence of Soils and Species on Root Depth (PDF), with links to scientific papers.

     
  9. Sundrop

    Sundrop Well-Known Member

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    Daniel:
    The analysis of the data in Table 1, showing plausible root depth ranges for a selection of tree species on different soil conditions, at the bottom (see page 5 and 6) of the article in your link, gives the following results:

    8 X 28 = 224 combinations of the tree species and the soil group were considered. Root depth had been measured or estimated for 178 combinations, in 46 was not measured.

    In 5 cases, or ~ 2.81 % of all cases, root depth was <0.5 m or 1.6 ft
    In 40 cases, or ~ 22.47 % of all cases, root depth was <1.0 m or 3.3 ft
    ------------------------------------------------------------------------
    in 55 cases, or ~ 30.90 % of all cases, root depth was <1.5 m or 4.9 ft
    in 53 cases, or ~ 29.77 % of all cases, root depth was <2.0 m or 6.6 ft
    in 15 cases, or ~ 8.43 % of all cases, root depth was <2.5 m or 8.2 ft
    in 6 cases, or ~ 3.37 % of all cases, root depth was <3.0 m or 9.8 ft
    in 4 cases, or ~ 2.25 % of all cases, root depth was <4.0 m or 13.1 ft

    Based on the above:
    The root depth in majority of cases (133 in 178 or ~ 74.72 %) was more than 1 m,
    only in 45 or 25.28 % of cases the root depth was <1.0 m.

    Only in 5 cases, or ~ 2.81 % of all cases, root depth was <0.5 m,
    in 173 in 178 or ~ 97.79 % of cases root depth was more than 0.5 m.

    It should be noted that the measurements were done on uprooted trees. Even a two-years-old will agree that the trees with the weakest, shallow, possibly unhealthy root system will get uprooted, not the trees with a strong, healthy one, and second, the deeper we go the more roots will snap off.

    It also looks like only structural and storage surface roots were considered in the quoted article. Fine feeding roots, usually <2 mm in diameter, other that inside the root ball that gets uprooted, would for sure break and remain in the soil. Those very fine feeding roots, not taken into consideration in the article, are often heavily branched and are supported by mycorrhizae that is an integral part of the tree rooting system.
    The whole is greater than the sum of its parts.

    All this makes the data the article is based upon of rather doubtful value. Truly reliable scientific study on root development and depth should be based only on measurements obtained by the method of almost microscopic observation during excavation or trenching.

    I agree though with the general assertion of the article that the tree species, age, health, planting density, soil type, silvicultural practices, climate, environmental stresses, all will influence the distribution of tree roots within soil.

    That much regarding the article in your link, Daniel.

    First of all availability of water and nutrients and the physical properties of the soil will influence tree rooting habit. Mulching trees will create favourable rooting conditions at the surface of the soil encouraging shallow root development on dry, sandy soils and on wet, clayey soils can cause too much moisture to stay in the upper layer of soil for prolonged periods of time pushing air out of the soil and causing root rot and dying. Such trees will be prone to disease and may be easily uprooted.
    An excellent illustration of what happens to the roots of heavily mulched and shallowly fed tree can be seen in this post http://www.botanicalgarden.ubc.ca/forums/showthread.php?t=85384.
    The practice is harmful to trees in the long run; proverbial long-term-pain-for-short-term-gain.

    By the way, it could be interesting to note that the deepest observed living roots excedeed 60 m or 197 ft in length. Here are some examples quoted in Wikipedia http://en.wikipedia.org/wiki/Root#Rooting_depths
    "Boscia albitrunca, Kalahari desert, maximum rooting depth 68 m or 223 ft
    Juniperus monosperma, Colorado Plateau, maximum rooting depth 61m or 200 ft
    Eucalyptus sp., Australian forest, maximum rooting depth 61 m or 200 ft
    Acacia erioloba, Kalahari desert, maximum rooting depth 60 m or 197 ft
    Prosopis juliflora, Arizona desert, maximum rooting depth 53.3 m or 175 ft "

    Here are the findings of the scientific study on Maximum rooting depth of vegetation types at the global scale http://sites.biology.duke.edu/jackson/oecol96d.htm
     

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