Meant to add, and this is just my opinion but what good would it do to contact an author of a book to tell him you think he published some bad information? He can't change what he published years ago or recall the books and put out new ones. Books aren't like the internet, with new information every day or week, unfortunately. A monthly gardening publication like Organic Gardening magazine (don't know if it's still around, even!) would be a more reliably current source.
There's a LOT of information out there in books that is tremendously out of date, and much of it has been proven wrong by ongoing research especially in Botany. Universities with Agriculture, Horticulture and Botany schools are constantly changing their handouts that are distributed - for free! - through your County Extension services. That's always your best source for current information.
If it's a tropical plant that you're growing indoors, possibly a County Extension in a southern state would have more specific info on those plants since they grow in people's gardens down here.
