It's a mobile nutrient deficiency issue, most likely. it could be influenced by pH. it seems your newer leaves are doing just fine...at the expense of your older growth.

Taking a wild stab guess at it, though, it sounds like you might be lacking in N...especially with the vein chlorosis being an indicator.

i'm also interested in hearing what the others have to say. however, i'd first check the Ph (as suggested by previous blogger) before arbitrarily adding anything. there's little to no uptake if the Ph is off.

What nc-crn said.

FWIW,

Bill

Spray feed them with Miracle gro (15-30-15) at half of the recommended dose and give them a few days. If you need to feed them this way again wait about 14 days before you spray them. Make sure they have good air circulation.

It's not uncommon for indoor plants to loose their lower leaves. As the plants grow the new growth can shade the plants lower leaves which will fall off from lack of light.

Alan

Sounds alot like when I had a calcium and magnesium deficiency, which was partly due to the pH being slightly off. I had to get the pH problem taken care of then supplement calcium and magnesium.

Thanks for the great suggestions and comments, that pretty much confirms what I had thought. I had never thought to spray the fert directly on the leaves, but it makes sense. I'll give it a shot. I expected to have some leaf drop when summer ended due to a drop in available light but this is certainly more extreme. I'll try to get something soon to test the pH of the soil. So a chemical test is best? I keep reading that the meters aren't accurate.

Thanks!

I've found that leaf feeding is the quickest, and safest, way to get nutrients to a plant when it isn't doing well.

Alan