Hi we have just joined your forum and are hoping to get some advice on dealing with invasive poplar roots in our raised beds. We live on an acreage just north of Prince Albert SK. Our soil is very poor so we thought raised bed gardening would be a good fit to our situation. The problem we are having is the poplar (Northwest and Tower) shelter belt we planted are liking the fertile raised beds. We have tried to remove them from the raised beds but it is a losing battle. What kind of barrior in the bottom of the raised beds stops this "invasion"? Any other suggestions?
Heavy-gauge landscaping plastic might work - try the kind that is typically sold as "bamboo barrier" or heavy pond liner. Other than this, I'd keep battling by chopping out the saplings as you find them.
