Placing the spagh.
around the pots will definitely help these, cannot hurt. Putting some spagh in your next potting for these, is what I'd recommend. Spagh. is not hard to work with, just more specific or precise as to when to water. Cattleya and Dendrobiums (except decidious Dends.) are the exceptions and never get spagh. (speaking, personal preference, not gospel
) In Winter, I always add some spagh. to my Vandas just to prevent too much drying out. I (personally) love spagh. and have it mixed in most of my alliances, more in some than others but, especially my Phals.
The spagh. should help with your concerns for these.
Good luck!