I understand this is an old thread, still hopeful that someone would answer my question. I have a slightly raised garden bed 8 feet away from a mature maple tree. The first season, I grew veggies, herbs, and flowers with very good results. At the beginning of the second season (last year), I noticed that the bed had been completely invaded by the tree with dense roots everywhere. I cut the roots, refreshed the soil, and planted the same things. They did not grow well, all the nutrients being sucked up by the big tree. Now, I am looking for a barrier to isolate my garden bed from the smart tree. It has to cover the bottom and one side of the bed. Any suggestions would be greatly appreciated. BTW, I cannot move the garden bed to a different location. This is the only spot that I have.

Dig a hole where your thinking about putting the draining pipe,fill up with water and see how fast it drains,repeat a couple times,you'll have your answer then.

Yes, the plan does warrant boxes. They will be on a large slabbed patio that is very geometric in nature. Through careful placement and usage I can take advantage of the hard edges and angles already in place to create a nice sense of unity. I am a designer, I can nerd out about this stuff for hours ;) Also, I was looking for a whitewashed look as well, as some of the brick on the back wall of the house has an aged look with white flecks... it would be a nice tie in to the boxes and wouldn't create such an abrupt change. Though tension is always nice.

I think a lot depends on the size of the deck and the furniture layout but you could replace these benches with planters for a nice look and a bit of safety .