Struggling Siam Treasure
 

I have a Siam treasure that I purchased almost 3 years ago. It's a little plant with 5 inch leaf span. The roots are nice and green and look healthy but the plant just won't grow. It flowered one flower but it didn't last long. Does that particular plant need anything different than any other Phal.? I have it with others that are doing just fine, any suggestions.

Not that I'm aware of, but plants are individuals, so maybe yours is simply a "shy grower".

I would read it as the flower was shocked, put out one flower, and now it is out of blooming season. Take care of it, and maybe next year. Phals often bloom once a year, but generally last about 3-4 months, so it seems like the bloom more often, but they don't.

Siam Treasure is a hybrid of lowii x pulcherrima. It could be that your plant takes after the lowii parent more so than the pulcherrima.
At least 2 growers that I have talked to have said that these need to be grow alittle bit cooler and during the winter months be kept drier than you would other phals. They can also take slightly brighter light. During the rest of the year they like to be watered well with good air movement, allowing to dry somewhat between watering.
I only learned of this after I had killed 2 plants and didn't want to try another, just seemed to fussy for me.

So, not really sure how correct this is, but it was the same instructions from 2 different growers at 2 different times.

Perhaps someone who has success with this hybrid will come along with how they grow theirs.

In any case. Good Luck!