I'll try to give it as much description as possible:

The seme is some King of Flowers or plants or w/e, and he somehows meets his uke, who works at a garden shop?

The uke takes really good care of his flowers.

I think the seme has long hair.

I remember a scene where the seme gives the uke the ability to see the flowers as fairies and the uke sees the flower fairies thanking him for taking such good care of them.

If this isn't enough information I'll try to put in more.

Thank you for you help~

Is this what you're looking for "Barairo Emperor"

http://www.mangaupdates.com/series.html?id=57386

Youre description may be a bit too "fluffy" for Kare Otoko ni Izumi o, but there are at least a few similarities ... ^^"

________________
"It's like love is a bonus in your life. Even without it, I'm just fine. I don't feel like pointlessly searching for it. You don't have to make yourself unhappy." (Ookami Shoujo to Kuro Ouji)

"Why does it rain?" - "To create drama." (Drops (Andou Yuki))

Moved to Yaoi/Yuri~