I had in-ground garden beds (made from trex) that were invaded by tree roots. I dug out the beds and sifted the soil to get rid of the roots. I then put down cinder blocks, 9 in a 4'x4' garden bed, with their top surface level with the top of the in-ground beds. I then put down two layers of 1/2" cement backerboard which is supported by the top of the cinder blocks and perimeter of the in-ground garden bed. I drilled drain holes about every 12" in the cement backerboard. Now I have a 16" air gap between the new bottom of the garden bed and the old bottom of the in-ground garden bed. I build a raised garden bed perimeter and set it on top of the cement backerboard. I'm hoping the tree roots won't reach up through that airgap into the new garden bed. We'll see... Don't use the Hardie cement backerboard that has grooves to help you break it to size. I tried that first and it broke at some of those grooves. Dug out beds and used thicker double layer of cement backerboard.

As Bihai says, so much depends on climate. When I was in Miami (Zone 10) my neighbor had a shell ginger that he refused to tend. By the time I moved away, it had a 30' circumfrence and knocked down a portion of the fence. Whover has to eventually deal with removing that thing will have to get heavy machinery. Here in San Diego it is still zone 10 but temps on average are cooler. Here, when I find a shell ginger that is even being kept alive outdoors, it is a special day. And the occasional one I do find is slight in size (compared to Miami) and usually somewhat scraggly and beat up looking. I tried Zingiber zerumbet here. It came up fine with foliage for 2 summers. The second summer it tried to flower, but the flowers never fully developed before winter. Then it didn't come up again the next season. Regards, Rick Clark

Sewer lines are typically invaded by roots where there are cracks or joints in the pipe. Generally, the larger, faster growing trees are the most likely to cause issues, and shumard oak is a relatively fast grower that can become quite large. It would be safer to go with a smaller, slower growing tree species, especially if your sewer line is older.

any chance at a pic?? i suspect you are trying to garden too close to mature trees.. and frankly .... trees ALWAYS win ... and you arent going to win.. just ask anyone in the hosta forum..who tries to garden under trees... they are super competitors.. and they always.. eventually win ... burying pots only works.. if you lift the pot out of the ground.. as often as the tree roots grow into the pot... trees seek water.. so if you water only the pots.. guess where the trees will go.. double down on that.. if you fert the pots ... you probably.. if you had the space.. need to move out about 3 feet from the trees.. and start new beds out there.. but even then. the trees will invade that... pots on top the ground will work. as long as you move those once in a while.. as the tree will grow up into those also ... good luck ..... youll need it. . ken ps: maples are the worst ...