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jenn_gw

Planting high, exposed feeder roots

jenn
12 years ago

I began gardening almost 20 years ago so I'm definitely not 'new to gardening'. However, it seems that all these years I either missed, overlooked, or ignored planting instructions (for trees and shrubs) to plant with the top of the root ball slightly higher than the surrounding soil, then mulch around the plant keeping it several inches away from the main trunk.

In real life and in illustrations, I see the feeder roots at the top of the root ball totally exposed.

Really?? Are the feeder roots (if there are any exposed at the top of the root ball) supposed to remain uncovered? I have always made sure they were covered with a little soil and mulch, being sure the plant is not set too low.

Now, this method of not digging a hole any deeper than the root ball, setting in the plant so it sits slightly higher than the surrounding soil, back-filling (so the root ball still remains slightly higher than the surrounding soil) and not adding any amendment to the planting hole seems foreign, but I admit reasons seem logical (except for the part about leaving the top w/feeder roots exposed!).

I have not yet seen a reason for leaving feeder roots exposed. Can anyone explain?

Comments (4)

  • rhizo_1 (North AL) zone 7
    12 years ago

    Planting high is most commonly suggested for heavy or clayey soils, though some settling of the root ball occurs regardless of soil type. The goal is to make sure that the top of the root ball NOT be buried in backfill.

  • gardengal48 (PNW Z8/9)
    12 years ago

    You don't want to leave feeder roots exposed if you can help it :-) Those that may appear on top of the rootball are less of a concern - really shouldn't be in that location anyway and usually indicate the root flare was buried too deeply by the grower/nursery. But those on the side of the rootball should be covered. Generally this is accomplished by mounding up the backfill soil to the top of the rootball.....a sort of mini-berm or mound. Or you can do the same with whatever mulch you may be using. And there us really no limit to how high the rootball can be.....depending on soil conditions, it could be completely above grade (as long as stability was provided), but with an appropriate amount of soil mounded to cover the exposed sides.

    While I don't necessarily agree with everything they recommend with planting trees, the attached link has a very good diagram of what a high planted tree should look like.

    Here is a link that might be useful: high planted tree diagram

  • jenn
    Original Author
    12 years ago

    Thank you for your responses, and also (gardengal) for the very interesting link.

    I understand about planting high for heavy/clayey soils, but I don't correlate planting high with not covering the top of the root ball with back fill (after all, you could plant low and still not cover the top of the root ball).

    I see many plants in their nursery pots with the very top-most roots exposed, and I just can't imagine why leaving them exposed after planting (on the top only) would be a good thing. Therefore, it makes more sense to lightly cover any exposed roots on the top after planting while still keeping the heavy mulch away from the base.

    We have heavy clay soil and citrus trees that have thrived for decades that I'm sure weren't planted high -- so did they survive in spite of that, or is "planting high" a precautionary method for the worst conditions? Perhaps our soil drains better than I assume it does.

  • gardengal48 (PNW Z8/9)
    12 years ago

    Planting 'high' is now a pretty well accepted and recommended practice for ANY soil condition, poor drainage or not. There's a variety of reasons supporting this - settling (collapse of the soil surrounding the roots - common with containerized trees and shrubs), less chance of overwatering, improved drainage, minimizing soil interface issues between native soil/backfill and the rootball soil and to maximize soil oxygen levels (lowering risk of transplant shock). It has been established that trees planted with at least a quarter to a third of the rootball above grade establish faster than those planted at grade level.

    Feeder roots should not be present on the top of the rootball - that is not their 'normal' location on a healthy, well-grown young tree. If they are present, it is an indication that tree has been grown too deeply, either in the field (for B&B stock) or in a container. Larger, structural roots are not so much of an issue as they are a) a better indication of a proper planting depth and b) not inclined to dessication like feeder roots would be. Regardless - virtually any respected and current tree planting resource will advise you NOT to cover the top of the rootball with backfill soil. Mulch is quite different but even then, mulch very lightly over the top of the rootball (feather out to a greater depth further away from the tree) and avoid any mulch touching the trunk.

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