The origin of the seaweed used is from the Gaspesian peninsula in Quebec, and it says the dilution varies; I suggest you still add water ( empty contents in a big basin and put half water in the container and add to the seaweed in the basin and funnel it back to the container. You will have half a bottle extra of diluted seaweed. Better be safe. That is why you are having that foul smell. It is still heavily concentrated I beleive.

I see what you mean about that product. It looks like it's supposed to be used as is. I think it would be OK to spray on your orchids right out of the bottle. Seaweed is not a strong substance and I've never heard of it burning plants or roots. Just use a little at first until you see how they react. Seaweed is great to use in the spring because it encourages root growth.

I also bought liquid seaweed from Rona. Mine was in a concentrate form (Marinis). Mine was pretty smelly too. I'd be curious to know about the 'smell' as well.

If a product says it's okay for roses, then it's okay for orchids. Most products don't mention orchids as I guess they're considered too exotic for the average application.