There is no item that gives 10 growth.  There's a few that give +10% growth,which is usually less than 1 point.

Are you sure that you aren't looking for 10 when you should be looking for .3?

sure it doesn't say 10% growth?  so if you have 1, I don't think you'd necessarily see it.

I think the hearts have different factors, know which it was?

I'm not talking about some ordenary item, Tuidjy. I'm talking about the heart that you get after killing that big wasteland monster that lurks where all the haunter/plaguestalker/naja monster groups are. It's called "whatever of summer whatever".

And I'm quite sure (though not a 100% sure) that the flavor text said it gives +10 to city growth and not +10% which would be rediculously low taking into account that you had to kill a 600 hp boss monster for it...

I just realized that I still have a final savegame from that game before I won through conquest. Turns out the growth section in my settlement also says: Heart of Moria (10%).

So, either they simply forgot the percent symbol in the flavor text or my eyes and/or mind played tricks on me.

Thanks for pointing me in te right direction. Next time I'll doublecheck before posting.

Still, I hope they're going to pump up the percentage a bit.