i doubt anything that allows proper drainage.. will stop a willow or an aspen ...

move the veg garden ...

and if you cant ... then work in pots .. and these trees will even invade those.. if you dont move them 2 or 3 times per year ...

when digging.. presume that EVERY root you cut in digging.. will branch and replace that lost with two or three ... and therein .. you can see the losing battle ...

good luck/ you will need it

ken

There is a product called Bio Barrier which is a fairly stiff fabric with "buttons" that release a root inhibiting chemical over a considerable period of time. The product does work if installed correctly - not all that easy since a considerable amount of excavation is required and the stiffness makes the product difficult to handle. It's also quite expensive, but might be worth it to you if the area is small. The web address is biobarrier.com.

There may be other similar products. Copper compounds will prevent root intrusion, so there may be fabrics impregnated with these.

Thank you both for your advice. BioBarrier is intriguing but the reason it works so well is because it's lined with a pre-emergent herbicide. Seeing as I'm trying to keep those sorts of things out of our veggie garden, I'm going to have to pass on that. Neat idea though, and copper might be a better alternative.

We've got an idea hatching to use pond liner, and then allowing for drainage out the bottom edges of the bed (slightly above grade). I think we'll line 2 of the 3 affected beds and see how it works out.

I do understand now that we've got a non-trivial problem on our hands, so we'll see what solutions we can come up with.

Thanks for chiming in!

Karin