http://www.250kb.de/u/060610/j/d006c143.jpg

Here is a link that might be useful: {{gwi:386154}}

Hannah,

Yellowing between the veins of older leaves generally indicates a lack of a transportable nutrient, such as Magnesium. What is the analysis of the Plantacote? It could be that it is too slow releasing for the needs of the A. x calidora. These plants are very vigorous and that means they need enough nutrients to sustain that growth. Otherwise, they will decline and die down or out.

I give my host of Alocasia hybrids a soluble fert solution every week and I use a higher nitrogen mix as well, occasionally supplementing with extra iron and manganese. Even under these conditions, some of mine get a little pale from time to time, especially in the summertime growing months.

Many, if not most, of these Alocasia like well draining soil mix as well, so if your soil is heavy and wet, that might be part of the problem. Healthy roots are a must for proper nutrient uptake.

Hope this helps,
LariAnn Garner
Aroidia Research

Here is a link that might be useful: Alocasia x calidora