Question
Hi, I have had a Hibiscus 'Holiday' houseplant for about 15 years. It has always flowered well and I have re-potted it and cut it back many times.  I feed it with Phostrogen and it has always thrived.  However, in the last 2 years some of the leaves are losing their dark green. They are now a medium green, which is not too bad, but the ribs and veins have completely lost their colour and are now a light cream colour.  I have seen leaf problems where the opposite has happened (i.e. green veins but discoloured or yellow leaf between) but cannot find the cause of my problem!

Answer
Anne,

I looked up Phostrogen on line as we don't have it here in Indiana and found there are several varieties. Since I do not know which one you are using I will tell you what I have discovered with my tree hibiscus this past winter. I had some palm food laying around so I gave it a try and fed the hibiscus with that. Because palms like very acidic food palm food is highly acidic. Within days my hibiscus started turning very dark green and in about a month it started developing flower buds. After that it bloomed off and on all winter.

I didn't find any cause for your problem either, it could be some missing micronutrients, but I do not know which one. I really suspect it is just to alkaline and needs to be more acidic.  I am a gardener and not a horticulture scientist. It is a tropical plant and most of those like acidic soils.

If you have more questions feel free to write again. Good luck.

Darlene