I'm not the greatest with vandas, but I am into raising babies.....I find giving seedlings something like peat moss or sphag gives them an easier time growing new roots as tothe increased humidity. They need more watering too.....my nursery (as I call the baby or small section) gets almost daily watering and misting to keep their humidity up. Also, I am much more careful about their temp's and never let them get too chilly for too long. Windy or hot days they will need more moisture and more waterings and protection from direct sun. Go careful with feedings, keep your nutrient mixtures really weak for the little ones. They burn really easy. Good Luck...
Connie