Just an Idea. We lined the insides of our wood raised beds with some thick weed guard fabric first and several layers of newspapers that we wet as we went on each layer. It has worked so far to keep seepage to a minimum.

do not use tar as it is toxic to plants. Won't kill them but not good for them. Just curious, why are you doing raised beds? Bad soil? Just like the look?

Thompson's Water Seal (or similar) works on concrete (and very well on tera cotta planters, too).

Looking for mixture of heights. I like the color of lantana but not just at the ground level. My plan is to put different lantanas in raised beds in cascading color. You know, top red, then orange, yellow, then bright yellow. To look like a flow of color like water cascading.

Of course, my mind and what I actually can achieve just takes effort and luck.

I have seen professional landscapers with raised beds especially at the beginning of subdivisions. Sometimes they look bad because of the white hard water stains. Others are perfect for years.

Thanks for the imput.