New growth in winter. Should I increase fertilizer?

[lusenok]

It's winter in upstate New York, days are short and cloudy with little sunlight. But my cattleyas and oncidiums put tons of new growth. Growing tissue requires a supply of nutrients, right? Should I fertilize more now?

I heard many times that you are supposed to reduce watering and fertilization in winter, especially nitrogen supply, without a really good explanation why.
I see that my plants are putting couple of new p-bulbs each so I don't want to starve them.
What should I do?

Can cattleyas utilize nitrogen/phosphorous well without good sunlight? What kind of nutrients are stored in pseudobulbs anyway? This brings us to some fundamental biology questions. Maybe someone can help me with this