Karen, these were grown to massive size by another grower who soaked their roots in fertilizer water every day. She also used kelp.
I'm not so diligent about fertilizer, I use a 30-10-10 orchid food once a week. But I make up for the fertilizer with the sun--they get lightly filtered sunshine all day in the summer and direct sun from a southern window in the winter.
Here's a video of these Vandas growing outside, just made last week:
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