I'm looking for the biggest selection possible of climbing flowers to add to the planter I built. Don't want to start from seeds. Who might have the biggest selection of these in Bangkok? Checked roadside places but selection isn't very big. 

Drive up to the Central Westgate Area... there are several mega-centers.

 

https://goo.gl/maps/MxasRkeQyVpTbXgs8

 

Also a bit further up past the mall (just past Thai Watsadu) is a massive Nursery complex...everything...and I mean everything. It's only 45 minutes from BKK (not rush hour)

 

https://goo.gl/maps/zeceEJgxHCbf7b1V6

I should add there is a perfectly acceptable range of plants at the Chatuchak market flower market section. Easy to get to via MRT / BTS. I just happen to live in Central Westgate area so I thought I'd fill you in on what I know.

That wood is going to look good to Termites....keep a good check on it.

regards Worgeordie

If you fancy a day out, you could go a bit further afield. The Nakhon Nayok road heading away from Rangsit has masses of nurseries. Turn left at khlong 15, and there are more nurseries than you can shake a stick at.

Checked the Central Westgate area. Great! As promised, MANY, MANY choices of nursery sellers. Thank you.