Raising soil level around gum tree

[mcolen]

Hi all<o></o>

I'm wanting to flatten out the back yard slightly which involves increasing the height of a retaining wall and back filling. This will cover the base of two gum trees by about 200-300mm. I've been told that doing this will kill off the trees for sure and I'm not allowed to get rid of them (by the wife).<o></o>
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I did read somewhere that if I lay gravel around the base/trunk and separate it from the added soil with a barrier to keep the soil out but let water through that would allow the trunk to stay dry and not die out.<o></o>
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Does anybody agree with this or have any other ideas?<o></o>
thanks

[Calm]

If you cover around the trunk of trees with woodchips etc you encourage collar rot. This would be the same with soil but the gravel may work by allowing the air to circualte aroung the trunk.

[Skew ChiDAMN!!]

It's really not good for the tree, for several reasons.

You haven't said what diameter the trunks are, but if they're smallish (say 6") you can cut the bottom out of an 18"+ black plastic pot, slit down one side of it so you can slip it around the trunk and use it as a retaining wall to keep the soil away from the tree's base.

You need a fairly large air-gap between the pot and the trunk... I'd hazard to say that 6" is about the minimum. If the gap bothers you, you can lay a few pavers or small slabs of slate around the top to minimise the visual effect, but you do need to leave enough ventilation that if/when you lift them off, the hole is about as dry as the surface soil. (Dark & moist = fungus.)

Larger trees, same principle but it's hard finding old pots to cut up at that size. Perhaps a few bricks as a retaining wall?

Given enough time the trees will fill the gap, but as they "grow into it" it doesn't seem to be as much of a problem as suddenly piling up the dirt all in one go...

(PS: The above has been whispered in my ear by she of the green-thumbs. Just thought I'd mention it while she wasn't looking. :;)

[Calm]

Only 4 to go Skew keep going you will make it tonight.