Ruh-roh...
Ya know...I can't for the life of me think if there's a proper name for a plant room aboard a spaceship / space station / Flying Castle. Seems there should be.
We have meadows and wheat fields and cornfields and ... well, enough to last. We also have fish-farming, synthetic rice paddies and hydroponics. Small vegetable gardens and livestock pens.
We have orchards and vineyards, even some natural vegetation in the form of a forest in the Flying Castle habitat.
We dream big.
P.S, All of these facilities are connected via a tubular elevator system with spherical elevator cars. This may sound silly, but when you move from Habitat A to Habitat B, your sense of down rotates a hundred and twenty degrees. Spherical is good.
Maybe you could install curtains in the greenhouse.