I don't mean to argue, there's no doubt that bill has WAY more experience with caladiums than I do, he probably got more than anyone on atp!
It seems that depending on the your source, many places do consider them heavy feeders, certainly that term is open for interpretation, but I tend to agree, they certainly can tolerate less feeding than other aroids, such as elephant ears,but almost every aroid I've encountered or read about stands to benifit from regular fertilizing.
What I read most often is to give them half strength atleast once a month. That's alot more often than your average garden plant.
Many sources simply list them as heavy feeders with no other advice, pretty generic advise really.
The 2 greenhouses I've worked in that grow caladiums on a reasonably large scale( around 5000 per year) both used fertilizer injectors to feed and water them.
Both had a separate injector for the heavy feed plants.
Most of the plants in these greenhouses received nutrients diluted down to around 10% strength, but they received it with every drop of water they got.
The other injector for the heavy feed stuff ran at around 30% and the caladiums and a few other plants got dosed with that for each watering, 30% is still quite weak but when you think about it, 30% dose 2 times a week, that's a lot of juice!
One year the heavy feeder injector broke down and they just got the same 10% dose as the other plants, most of the caladiums got tossed out that year they spit out leaves that were almost half the size they usually produce and even when they got back of the strength they seemed to prefer, very few of the plants recovered enough to be marketable...
My own personal caladiums grow right under my colocasia, and are exposed to the same feeding regimen as the elephant ears, which I dose once every 2-4 weeks will DOUBLE STRENGTH fertilizer, I use 11-55-11, and never have any issue unless I sprinkle the water soluble granules directly on the plants.
I don't think the caladiums really like that much, but they certainly tolerate it just fine.
