Sorry, this post may be a little too late for you..
we order pre-made garlands...Charge 'em for making your life that much easier.
I've used those 3M things..they're good...and they come in different "strenghts"...Some places are still skeptical though, so I'd ask the venue if it's ok before you assume that you'll use them.
My BEST suggestion...When you don't know how to mount something, where to put something, or what to do with ANYTHING going into a reception hall or church...ASK THE VENUE. Each place is different. Some places could tell you "heck no, you're not putting anything around this door no matter how you mount it"..others may be ok with you supergluing it to the wall (haven't come across any like the latter, though lol)
A lot of times, just asking their coordinator...who has seen this done every weekend of her career there...will know EXACTLY what to do in the situation...I just call and openly admit that I am stumped or concerned and 99% of the time they make a great suggestion...or tell me that the bride can't do it at all.
If all else fails, never be afraid to tell the bride that it can't happen. Then suggest a similar achievable look. If it's over budget or not what she wants...oh, well for her!
And we do put the flowers on garlands on site. Weave 3-4" stems into the garland. No glue on site!!! It can get messy and you don't want to mess up the carpet! However, if you didn't budget for a hefty labor charge, glue the day before b/c on site design is very time consuming.
Dana