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Raised bed around existing trees
anika
Posts: 3
Hi, I am looking for advice about whether or not trees can survive if they have raised beds built around them. We moved to a new house and the garden has 2 foot high raised beds around the fence line. There are three very tall conifers (about 30 ft high) and an apple tree in these beds. We have dug around the base of each of these trees and found no roots after digging nearly to the bottom of the raised bed. So the soil level is about 60cm up the trunks of the trees. Is this safe? Will the trees rot?
Thank you for any advice you can give.
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Posts
I don't think the trees will be very happy at all. It's usually recommended that you don't change the soil level around trees. I'm afraid I would remove the raised beds if you want the trees to remain healthy
Gardening in Central Norfolk on improved gritty moraine over chalk ... free-draining.
Thank you for your reply, yes I think we have a lot of work to do!
I would be surprised if established trees were affected by soil against the trunk. Ground levels change in nature.
Two feet is a bit different to six inches.....
I have soil banked up round a conifer and a pine - on a slope. They're fine, but it's a lot less than you have Anika. You might have to wait and review it after a year or so.
Have you any idea when the beds were built? If it's been a while, you might get away with it, if they're new - maybe not so good.....
I live in west central Scotland - not where that photo is...
Raised soil levels round tree trunks won't be good for them in the long term. If you want to keep the trees it would be best to remove the soil so the trunk is exposed right down to the base.
I'm wondering whether it would be possible to clear the soil from around the bases of the trees and build some sort of barrier with a few inches air gap around the tree trunks, so that you can keep the trees and the raised beds?
Gardening in Central Norfolk on improved gritty moraine over chalk ... free-draining.
It's not so much the trunk that needs to be exposed. The most important thing is that the trees roots have to be able to breathe and are able to take oxygen from the air with their very fine hair roots. Even an inch too much soil can be enough to damage the trees systems, because the soil gets too compacted.
Roots not getting enough oxygen is the reason why trees that have been planted too deep often sulk and die after a few years. It is recommended that the upper tree roots only have an inch (or less) soil on top of them after planting. That's also why trees need a drip line.
Sometimes that means that if you have a pot grown plant you'll have to plant it on a little mound.
Last edited: 10 February 2017 10:52:17
This is a good article about the subject: http://aggie-horticulture.tamu.edu/earthkind/landscape/protecting-trees/ (hope this is allowed)
Maybe if you made a circular raised bed somewhat similar to a polo mint with a few inches of breathing room around the trunk? Dont have 2ft in height though just 1 foot will be fine and plant only those plants that dont need a deep root system. You could then have a lovely display of colour around the tree and the tree can steel breath and the trunk is not prone to rot as no soil is touching it.
I know a field where the owner cleared a stream and did a bit of sculpting with a digger. He piled the soil high round some mature oak trees. They died.