Plant shelving must work for you.  I’ve used many types over the years, and I find that the best may also be one of the least expensive.  Plant shelving must be easily adjustable, and with Hoyas rapid growth being able to move it up or down in a hurry is invaluable.  For almost 20 years now I have used closetmaid wire shelving.  There is no need to worry about uneaven floors, because the “standards” (what the shelf bracket fits into) mount directly into the wall.  There are many different widths that can be used.  I do not have a curtain in my entire house (I’m proud of that fact), and have used the Closetmaid system as window treatments throughout the house.  It may not be for everyone, but I love it for its versatility – you can even hang baskets from the shelving!