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karin_mt_2

Keeping tree roots out of beds

karin_mt
10 years ago

I know that the problem of tree roots invading beds is a common topic around here. In my perennial beds I think it's a fact of life and I intend to adapt the plantings as our trees mature (which is certainly a wonderful thing overall).

But in our raised beds in the kitchen garden, I can put a liner at the bottom of the beds to keep the tree roots out. What would make an effective liner? Would weed blocker fabric be strong enough? What about window screen? Or both?

The trees in question are aspens and willows.

Last year was pathetic as I watched the plants in 2 of our raised beds wither all summer long, no matter how much water I gave them. So this spring I intend to take the soil out of the beds, put a liner in, and replace the soil. Sounds like an excellent workout, doesn't it? :)

Thanks for whatever wisdom you can share!

Karin

Comments (15)

  • auron22
    10 years ago

    Good luck preventing the willow from disturbing anything. I had one 10 years ago and it was a nuisance. Such a beautiful tree, but I don't plan on ever planting one unless I live on like 10 acres with a small pond. They are notorious for their massive drip line, and may be what is causing the wilt. I hope your idea works. This is all I can offer :(

  • molie
    10 years ago

    No suggestion at all. Maybe someone with more tree experience (tree forum) has advice.

    Willows are beautiful but hard to control. We had one in our yard when I was growing up. It did lots of damage because it was too close to the foundation and my dad finally took it out.

    I have to agree with Auron22's comment about a huge lawn with a small pond as the perfect setting for a willow. They need space to show their beauty and are best viewed (I think) from a distance ---- plus they are kind of messy ---- another annoying quality. But I did love the sound of the branches as they rustled in the wind!

    Molie

  • karin_mt
    Original Author
    10 years ago

    Sigh, yes I do love our willow trees despite their bad reputation. They are at the back edge of our property and are far from septic field and foundation. So far they have been trouble-free and highly appreciated, although I do keep after them with pruning and limbing up. But now they are getting big enough that their roots are venturing over into the raised beds. Can't blame them!

    The tree forum is a good idea. I don't think I have ever been to the tree forum. Are they nice over there? ;)

  • molie
    10 years ago

    Yes, Karin, there are very nice AND helpful in the tree forum :) They've helped me with a few problems before & I'm betting someone there will have a tip for you.

  • aachenelf z5 Mpls
    10 years ago

    My father use to line a brick planter along the front of his house with tar paper because of the huge maple trees nearby. It seemed to work and I don't remember him replacing the paper, so it must last for a long time. However that was years ago and maybe tar paper has been proven to be toxic or something. Don't know.

    I know screen of any kind won't work because the roots will come right through the tiny holes. When I built my raised bed, veggie garden over 15 years ago, I lined the whole thing with heavy, black plastic and put the drainage holes along the bottom sides so tree roots could not work their way up through the holes. So far, it's still working.

    Kevin

  • karin_mt
    Original Author
    10 years ago

    Kevin, that is very smart and is exactly the type of idea I was looking for, thanks!

    Mollie, thanks for the reassurance. I will also post on the tree forum to see what other ideas are out there.

  • NHBabs z4b-5a NH
    10 years ago

    I had a half whiskey barrel planter sitting right on the ground and the maple roots found its way up into that. So I think that anything that will let water out will also let roots in. When I replaced the planter I set it up on bricks, and air space has prevented root invasion. I realize that isn't helpful in your situation, but realistically, I am not sure if there is anything you can do to keep aggressively rooting trees from invading a bed with good water and nutrients. Is there another area farther from the trees for your veggies?

  • gardengal48 (PNW Z8/9)
    10 years ago

    Aspen and willow are perhaps some of the worst choices of trees to be located close to raised beds of any variety. Both have very aggressive, spreading root systems and both will hunt out sources of water and nutrients. Or IOW, any enriched soil that might be used to fill the raised beds.

    I agree with babs above.....there is really nothing you can use that will keep these tree roots out. Your only alternative is to locate the beds as far away from the trees as possible.

    FYI, plenty of generally well-informed/knowledegable gardeners frequent this forum that can supply answers to question other than those directly relating to perennials :-)) No reason you can get perfectly adequate answers here.

  • molie
    10 years ago

    Absolutely true, gardengal148, that there is great information of all types here on this forum. I did not mean to insult anyone but thought the tree forum might include arborists or other professionals who are current on new tree products or techniques.

    Molie

  • karin_mt
    Original Author
    10 years ago

    Thanks for the thoughts, everyone.

    We've got an idea hatching that is somewhat along the lines of what Kevin suggested. We are thinking of using pond liner at the bottom of the bed and doming it up in the middle to direct drainage out toward the edges of the bed. The bed can drain through the sides, which is above grade. In theory this would make a dry spot directly under the bed so maybe tree roots would have no motivation to go there.

    Our plan is to line 2 of the 3 affected beds and see how it works out. If it works I will let you know (although it will be awhile before I really know).

    Thanks for chiming in!

    Karin

  • mxk3 z5b_MI
    10 years ago

    My grandmother's neighbor had the most beautiful willow trees on her property, when I see willows it brings back many happy childhood memories of when I would spend summers at my grandmother's.

    I also have the memory of my grandmother b*tching up a storm over the willows, lovely as they were, since they often got into the sewer lines and she'd have to pay to get the lines cleaned out.

    Anyway, I've used spin-out bags to plant hostas in beds under maple trees, have worked beautifully so far, though this is not an inexpensive option. If you do a board search for spin-out you'll find info, also search the hosta forum, that's where I first read about them. I believe the fabric is available, too, but I purchased the bags.

  • aachenelf z5 Mpls
    10 years ago

    Karin

    That sound absolutely brilliant! Pond lines are thick and as long as no moisture gets through, tree roots should stay away. Mounding it in the center is even more brilliant. I'm impressed.

    Kevin

  • karin_mt
    Original Author
    10 years ago

    Thanks for the vote of confidence Kevin, but all credit goes to DH, he's the smart one around here. But I do the digging, so at the end of the day we balance out. :)

    I like the idea of spin out bags to allow hostas to survive in beds that are planted under trees, so thanks for that suggestion, mxk. I will take that on maybe next year. I imagine that digging under a tree to install them is no easy task.

    We purchased this house as new construction in 1999 with nary a tree in sight. Boy were those early years windy and barren. We are just so appreciative of having trees and shade so I am perfectly willing to deal with the consequences of having trees in the gardens. A photo is attached, showing one of the willows limbed up to make a graceful arc over the walkway, which I really love. The raised beds in question are in the background, with another willow to the left of them.

  • molie
    10 years ago

    Karin, those willow leaves look so beautiful, so delicate against the blue mountains! The fact that you have a windy spot means you must also get to "hear" the branches rustling in the breezes. I think the sound of them is what I miss most about the willow I remember as a child---- that and running through the long, sweeping branches that almost touched the ground.

    Molie

  • Robyn Lee
    3 years ago

    I have the same issue with my raised beds infested with willow roots... seeing as how this post is 7 years old I am curious how your pond liner worked out!! I am leaning towards this idea and would love to hear how your beds have faired. Unfortunately, my willows are much much closer to my beds than yours.