Invasive roots from surrounding big gum trees in Raised bed

by Eve
(Western Australia)

I live in a hill area of rocks and big gum trees. Our house practically sits on a rock. To find a good spot of deep soil is hard. Whenever I find a spot to plant anything, initial growth are wonderful, but soon they die or turn unhealthy.
If I plant in a pot, I have to raise the pot up, so the root system from the big trees can't invade through the draining hole.
I am planning a raised bed veg garden. Since it is impossible to plant directly. I plan to cover the surface with the tree mulch, then cover with large black plastic sheet, then on top of it a large piece of corrugated iron sheet, Which I happen to have. I will build a raised surround with large limestone which I get for free. I also have plenty of mulch from recent tree cuttings. Can I put in the raised bed first layer with this tree mulch, sprinkle with chicken manure pellets, then layer with brown leaves, which are in abundance in my yard, then with manure and then layer with more brown leaves, then manure, until the desired height? Finish on top with top soil.
Will this raised bed work for my situation? Can I get some advice in improving it?
The last time I built a raised bed, I put a thick layer of plastic sheet at the base and built around it with bricks, and I put good potting mix for the veg bed. However after a year, the root systems from surrounding trees broke through the plastic and the raised bed were congested with roots from surrounding trees, choking my herbs and veggies.
I really want to try this and be successful. Please advice the best way. Thank you

Comments for Invasive roots from surrounding big gum trees in Raised bed

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Apr 04, 2012
Raised beds not directly on soil.
by: Jane Pennington

In the UK I don't know gum trees but have experience of raised beds. I have also researched gum tree root invasion.
I read about raised beds before I sited mine as they are on gravel on top of rubble. This makes it similar to your situation insofar as the beds are not directly on top of soil, 2 beds at 600mm high and 2 at 450mm. I half filled them with tree chippings directly onto the gravel. It was difficult to get information on using chippings in raised beds but a U.S. blog okayed it for me. My thinking is this will eventually rot down over many years but it will provide drainage for the beds. For this first year I filled the remaining space with commercial compost. At the end of the season I'll enrich the spent compost with my own compost, and anything else I can get to improve the 'soil'. I was going to put topsoil in but decided to treat the raised beds as giant pots and improve it year by year. This NO DIG site has good information on composting if you check it. Making your own compost can be done in various ways and you will find something suitable. I've already got carrot and lettuce seedlings in my beds.
For the gum tree roots I found the following:
" need to make sure there are no holes in the barrier you're building. Sheets of steel will have spaces between them so you need to seal those off. Landscapers will often use heavy duty landscape fabric as a root barrier... in practical terms trees will invade darn near anything you do - up to and including a concrete barrier it would seem (over time anyway)".
"An advantage of a raised bed is that I was able to install a layer of root-barrier matting underneath to exclude foraging roots from two nearby eucalypts. A continuous piece of geo-textile fabric stretches across the base and up the sides of the frame, allowing water to drain through but keeping tree roots out. Within weeks of planting out seedlings of lettuce, Asian greens, rainbow chard and celery, we were picking veggies for meals...given the bed is only 3m square in size, we'll focus on quick-growing, continual-cropping veggies, carefully timing plantings to ensure a rapid turnover of edible crops".
And finally, "Planting under Gum Trees:
To maximize your success establishing new plants to grow under gum trees, plant them as close to the trunk as possible. The reasons you do this are: there are very few tree feeder roots to rob your plant of nutrients and moisture. The second and less obvious is all about increasing the moisture of the soil.During rain, a lot of water runs down the trunks of the tree and hence toward your newly planted plant"(this last extract may or may not be of relevance to your situation).
It seems to me that you need as much inorganic matter as possible between the ground (and thus the tree roots) and your planting medium. I would also be tempted to put some of the limestone down as well - it all depends on how high you can make your beds.
Good luck. Jane

Apr 04, 2012
Raised Garden Beds
by: Lorraine

Yes you can put your raised garden bed on anything even cement. As long as the height on the bed is tall enough to accommodate the roots of the plants you are growing.
All the organic matter you put into the raised bed will really improve it. Try adding heaps of compost as well.

Apr 05, 2012
Thanks for helpful feedback
by: Eve

Thank you for the helpful feedback. I did pour sand on top of the corrugated iron sheet and layered on top of it with fibreous fabric. I then lined the whole bed to the side with pond liner. Recently, I happened to visit someone who used the pond liner, pour gravel at the bottom and he place at the base pluming pipe horizontally at the base and joint to both end vertically slightly higher then the raised bed. He punch hole at the base of the pipe for watering purpose. He then top up with top soil. I am going to to the same, but will fill up from the gravel onward, layer of mulch, autum leaves, manure and so on to build it up. Summer in Westers Australia can be very hot and dry. And we have water restriction. My idea is I can water from the pipe on both side, even feeding it with fertilizer. As for now,I only manage to put the liner. Will stop for a while until next two weeks when I have time to continue this project. Welcome more helpful feedback. GOD bless.

May 01, 2012
Barrier to stop roots and weeds
by: Alf

Yes you've really got to have a good barrier. I've used sheets of corrugated roofing iron to stop a bad invasion of kikuya grass (not sure of spelling and I think there are lots of different types in world). This creepy grass even came up from 2 feet under before, so I had to dig down almost 1 metre and put the iron around the edges of the garden. It lifted and cracked the path too.
Just make sure there are no gaps as the others have said. Plastic is useless, but I don't know about landscape material.

Build up your garden soil by chucking everything organic in you can. Grow a nitrogen fallow crop or lupin or similar, see the page on here - is good for ideas.

Despite all the above, if a tree wants to grow roots it will. So going high with your garden is the best, and if said garden ends up pushed higher and out of kilter well then a chainsaw perhaps?

Jun 01, 2012
Raised garden bed
by: Rod

I've had the same problem with gum tree roots,tried every the end I made 4 beds of the ground.first I laid 3 brick pallets end to end,each are on a brick.then I placed corrugated iron over the pallets,then boxed it with treated pine,then lined it with concreters plastic, filled it with compost,soil and manures ,bingo works a treat.still going strong after 5 yrs

Feb 11, 2013
Chemichal Solution
by: Ajosin

Use Cu (Copper) to stop the roots. Paint it on the textile fabric for added protection and face it down. There is a commercial product out there (Microkote) but it is expensive. You can make your own a lot cheaper.

Microkote used to be made under the brand-name SpinOut by Griffin L.L.C. until SePRO bought the rights. After the re-branding they added other metals labeled as "nutrients". In my opinion this is all marketing; the roots will be stopped and not absorb anything near the Microkote layer - so really the only active ingredient is the chemical that stops the roots from growing further (this chemical is copper hydroxide which was the original ingredient in SpinOut).

To make your own.

1) Buy some dry Copper(II) Hydroxide, this is used usually as a fungus pestizide. Interestingly, SePro stuff can be bought on ebay (, this is probably the same stuff they put into Microkote. Other sources are
KOCIDE 3000 (made by DuPont) or
2) Dilute the Copper(II) Hydroxide in latex paint. The original SpinOut was made with 13 oz/Gal of Copper(II) Hydroxide (source: Remember to account for the original concentration of dry Copper(II) Hydroxide in the pesticide bag (this is typically 50%, for which you would add 26 oz per Gal of latex paint).

Remember to read all the instructions in the bag when handling pesticides.

This costs about 10x less than buying the Microkote solution which is over-priced and over-marketed (b/c of those extra additive "nutrients") in my opinion.

Feb 25, 2013
Zep Root Kill in latex paint?
by: a1689baptist

Zep Root Kill (90% CuSO4)
I've just removed four 5-gal buckets of a neighbor's pine roots from my raised strawberry bed and need to do something. I want to use copper sulphate in latex paint as described in the above post by painting plastic shade cloth with the material and placing it face down at the bottom of the bed.

Is there any danger of strawberry roots (or any 'friendly' roots) drawing toxic stuff into my berries/veggies?

Jun 24, 2013
just starting out
by: vicky

I would like to build raised beds near an almond and orange blossom shrubs. I have been reading everyone's comments and yes I agree I don't particular like using any chemicals in the garden. Just wondering Eve how did you go? Which option did you choose?

Jul 01, 2013
My raised bed
by: Eve

Hi Vicky,
After preparing the base for my raise bed, I did not install the pipe at the base, and also did not put layers of leaves, manure etc to build up the soil.
Some of my congregation, ordered Pre mix soil for growing veg and fill up the raised bed. The problems I found is there is nothing organic in the soil they bought for me, very sandy and and heavy. When I planted the seeding, it refuse to grow. So far I only manage to grow chillies and sweet potatoes in it.
So I have been digging in scrapped from my juicing and kitchen scraps.
The base seems to work until now, no root invasion yet. My worry is in another few years it might break through the barrier, as it is just very persistent all around the garden.
Happy gardening.

Jul 26, 2014
Easy solution to roots invading raised garden bed
by: Anonymous

I placed a raised garden bed on the ground after laying newspaper etc down in a thick layer. After about 6 months roots from nearby palm trees had grown up through the bed, matting thickly and stopping anything else from growing.

I removed the dirt and the bed to about 1" or 2.5cm below ground level. Levelled the area off with large wood chips then placed a heat treated (not pesticide treated) pallet on top. Staple gunned shade cloth (or you could use any other porous ag material you want)tightly over the top of the pallet then placed the raised garden bed on top and refilled with soil, compost, manure etc. It is now a very productive vege garden and has no roots growing up from below. The pallet was free and the shade cloth a few dollars.

Aug 20, 2014
Raised vege patch under gum trees
by: Anonymous

Just a caution some gum trees
ie tuart trees in australia act much like a pine tree as they can drop leaves and make the soil underneath acidic.

Nov 25, 2014
tree root invasion
by: Martin

yes the gum trees in OZ are very invasive i am sure that the tree roots have brains at the feeder ends because we removed a water tank recently, it wasn't leaking and you should have seen the root development under the tank, they knew the water was there but could not get to it. Makes you think?

Mar 31, 2015
Tree roots
by: EJ

Roots are relentless eventually growing thru anything. They also have hydraulic pressure on their side, as they can move/ crack concrete streets and sidewalks.
I plan to rent a ditch witch and go all around my garden (4 sides), and go as deep as I can with the thing. If it doesn't work (I'll know next year)then I am going to literally raise my boxes off the ground about 1' high and line the bottom of them with corrogated tin sheets. That will surly solve my problem with roots.

Dec 06, 2016
Roots of near by trees going up the bore holes in my parsnip bed
by: Anonymous

How do I stop this they only go where the feed is in the bore holes

Dec 07, 2016
Stopping tree roots
by: Anonymous

Don't think you can stop them. unless you use a strong physical barrier as suggested above. Otherwise move the parsnip bed or get rid of the trees.

Apr 30, 2019

We have eucalyptus roots invading our garden beds and strangling out veggies. We were going to dump all the soil, throw it away, line the bottom with material and add an inch of gravel on top of the material and buy new soil and refill. Will this work? We don't want to ever have this happen again. Or should we add bottoms to the garden beds and if so what kind of bottoms and does it need to be raised off ground and if so how much? HELP!???

Oct 30, 2019
Uke root invasion
by: Peter

Eucalypt roots will find any minute opening in your barrier and yes, the root tips do have a brain like functioning that explores any opportunity in its sub terranian environment. (F Baluska, M Gagliano and G Witzany Univ of Bonn) I have stopped them with many layers of builders plastic under my raised beds with the plastic edging stapled up the outside of the wooden raised bed so I can see any attempts of invasion. No roots so far after a few growing seasons. Hope the plastic lasts.

May 03, 2020
Tree root NEW
by: Anonymous

I make box out of old pellets using pellet on bottom and using board from another pellet for the sids about 300m deep. And boards to fill in the bottom pellet. Water can dream through gap in bleeds 2or3m. Stand on 4 bricks to keep away white ants.

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