I recently built a deck, and we are looking to make a privacy wall using pencil hollies. As I was making sure weep holes weren’t sitting on joists, it occurred to me that the way that these planter troughs are positioned, the will set between two 16” o/c, 2x8 joists. Each (4) planter will span roughly 6 decking boards and will likely be around 500lbs initially with gravel, dirt, and a young plant. As the plant grows, it may gain some weight as well. Is this a dangerous amount of loading for these conditions?
Side note. I have a plan to route excess water away from the bottom of the planter.