Vandas too many yellow leaves *(

[raybark]

There are two things going on, in my assessment:

The first is that vandas are really vines, so the loss of lower leaves is perfectly natural as the plant grows.

I believe the second is the need for more water. Vandas are really thirsty. I like the concept of repetitive dousing, but two, two-minute sessions isn't cutting it, even if repeated in the afternoon. I suggest dropping the afternoon session and increasing that in the morning.

When I was still growing vandaceous plants in a greenhouse in PA, overhead watering was for 30 minutes at 5:30 in the morning.

More speculation: bigger plants have bigger reserves, so any stress will be more easily handled (without as much lower leaf loss).

[Dorsetman]

If the problem is watering, here is advice from a well known Vanda breeder, which I follow.
Water thoroughly, and as soon as finished, look at the roots. Any which are not completely green, water again. Repeat as aoften as necessary until all the roots are green. Then leave until all the roots are white, and start all over.