Finishing off deck with planters - Seeking advice

[Lincoln Myers]

Hi,

William O'Connell replied to a post of mine a couple years ago, and included a picture of his deck. I tried to send a PM to him, but no luck.

Here are some links to his posts:
http://www.sawmillcreek.org/showpost...8&postcount=14

http://www.sawmillcreek.org/showpost...1&postcount=16

I am now trying to emulate his planter, block surround. I bought some concrete block 8x8x16 w/ 1 finished side (split face). I'm planning on stacking them 2 high and using the internal cavity as planters.

Question, how should I stack or secure the block? I initially thought I could just use block adhesive, but after thinking it over, mortar may be better. Can anyone provide me any advice?

Thanks,
Linc