I live in an apartment and I love gardening so a couple years ago I built a pair of planter boxes to sit on my balcony railing. I went to Home Depot and got some wood (pine I believe), stained it, assembled it and then applied a couple coats of polyeurethane to seal it up. They looked great for a few months but eventually the boards on the side started to buckle and pull the screws out on one of the boxes. I went back and made planter box V2 with longer screws and I applied the poly to each board before assembling which made the box much more sturdy. Unfortunately, after a recent bout of heavy rain both boxes are heavily buckled again and will need to be replaced.What do I need to do to ensure that these boxes last more than a season so I don't need to build a new set every year? Should I be using a different kind of lumber like some kind of treated wood? If so, is polyeurethane even necessary after staining? Are there other things that could be causing issues?Any advice would be appreciated! via /r/DIY http://bit.ly/2FPnS6R
