I've used white PVC downspouts as garden edging since I bought my place in 1998, and I just put in beds for a wonderful neighbor whose west bed has been a bone dry weedy oven for her treasured hibiscus for the years since her now deceased husband planted them, plus her careless lawn mowing guys are always fatally weed eating her plants, plus her insurance company told her that her east wall could not get any splash back ( I planted lavender ruellia there, just cut back when I took the pic). I fed the soil heavily, watered deeply, then applied scavenged cardboard and newpapers she saved then covered that with a thick layer of tree trimming mulch after cutting back the desperately dry hungry hibiscus. Now that the beds are fertile and damp I told her that those hibiscus that she holds so much sentiment for should look stunning by early July. At 84 after multiple heart attacks she really feels the clock ticking so it was a joy to solve this perennial problem for her. I will straighten out the edgings then hold them in place with thin steel rods I scavenged that I will pound into the ground all along the outside edge. She has spoiled me with awesome leftovers since 2000! Best neighbor EVER!!