Depth of raised garden beds?

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Depth of raised garden beds?

Postby karyn » Mon Feb 24, 2014 6:44 pm

Mum's vegie garden is completely over-run with gum tree roots and is hydrophobic. We've decided to put down some weed mat (yuck) and sit several raised garden beds on top of the existing bed. The ones she likes are 40 cms deep, is that likely to be a problem for any vegie roots? Will gum tree roots come through weed mat? They will be 3m x 1.3m x 40 cm deep. Is the galv going to get too hot at all? The drainage will be fine as they will sit on top of her existing vegie garden, 1 railway sleeper high. We have tried wetting agents, compost, organic material etc, but digging is the only real answer and she's now in her 60's.
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Re: Depth of raised garden beds?

Postby Pam » Tue Feb 25, 2014 5:30 am

Will gum tree roots come through weed mat?

They can demolish concrete. In short, I think that eventually the fibrous roots would work their way through it. They're pretty persistent. I'd like to think she'd at least have some time though that she was able to grow there with ease.
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Re: Depth of raised garden beds?

Postby gardenlen » Tue Feb 25, 2014 6:22 am

g'day karyn,

myself i would be thinking weed mat won't do the job, you may have to bout in one of those rubber root barriers?

how close are these gum trees to your mum's house? the rule of thumb safety distance is the max' height of the tree + 50%, so a tree that can grow 50 meters means a safety distance of 75 meters.

we have galv' roof raised beds, the heat issue doesn't exist, we grow many plants about 75 - 100 mm from the edge, all grow well we do this with tom's beans and onion family at least so they can hang over the edge, save some tying up. our beds are full width of the sheets high, 6 meters long and 1 meter wide, we should have used 8 foot star pickets driven in app' 500mm, but no major worries, always lessons to be learnt, he beds produce well. no issues with getting cuts from wire or roofing material, the higher stakes will also make it easier to stake plants up. we have evolved from 10" high beds through to these, these are best as once built no bending.

not sure if i can attach a pic or 2 if not i'll take some time later to add to the gallery, just thinking with beds this deep you could almost lay the rubber root barrier under the beds, they will still drain, might slow the worms down but?

we are yet to build a shade cloth cover over them to keep those vandal king parrots from the beds, this year for the past 10 is our best for capsicums, getting ready for the brassicas now

for got to say buy second hand material, or get hold of second hand, s/h star pickets may be hard to get, but we went to scrap steel yard and got some of our roofing for last 3 beds, older roofing stronger than new chinese stuff, 1st 3 beds cost &100 each last 3 cost 100 for the three. s/h metal costs you about .50 cents per kilo. if 6 meters long too much do 4. lsat beds stronger as we only needed to tie in 2 opposite corner, with 1st beds we order 1 meter sections for the end they had to be tied in 4 corners

keep in touch

100_1152 #1+4 toms,eggs, beans and more tomes.jpg
100_1112 last bed.jpg
With peace and brightest of blessings,


"Be Content With What You Have And
May You Find Serenity and Tranquillity In
A World That You May Not Understand."
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