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Raised beds in poorly drained soil


Planting balled shrub and indications

Most plants require a soil that drains properly, otherwise their survival is at stake.

You have assessed the soil's drainage where you would like to plant your tree or shrub. The verdict is in : your soil drains poorly. What can you do?

In sites where the soil is compacted or poorly drained, it is always best to choose trees and shrubs that are adapted to these conditions.

If you want to try your hand with plants that are not adapted to such sites, you will need to opt for other solutions, such as : reshaping the slope, raising the ground when possible or installing a drainage system. Because all of these operations are usually complicated and very costly, you might like to try another approach: raised beds.

How to achieve raised beds

Here are the steps to follow to make raised beds and help your tree or shrub grow in poorly drained soil.

  1. If your tree or shrub is growing in a container, remove it and prune any root-bound roots.
  2. Open up the top of the root ball to expose the plant’s collar. Measure the height of the root ball to this point. Also measure the width of the root ball.
  3. Dig a hole about 2/3 as deep and three times as wide as the root ball, with sloping sides.
  4. Do not add any amendments or fertilizer to the soil you remove from the hole, and do not place any gravel in the base of the hole.
  5. Place the tree in the planting hole, making sure that it is straight.
  6. Expose the top half of the root ball, if you are planting a balled and burlapped specimen (see the tree and shrub planting steps section).
  7. Stake the tree, if necessary.
  8. Backfill the hole, in layers, using the soil you set aside when you dug it. Add extra soil if necessary to form a small mound, not more than a third of the height of the root ball, to prevent the roots from drying out too quickly. Do not cover the collar.
  9. Do not form a saucer to trap water, but do water the plant thoroughly and deeply. Add more soil if necessary.
  10. To avoid aggravating soil aeration and drainage problems, do not add any mulch.
  11. Remove the wrapping and anything on the trunk (twine, tags, pins, etc.).

Illustration: Espace pour la vie/Audrey Desaulniers

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