Ideas:
Humidifier (item) has a radius like the lamps, allows mushrooms to be in other rooms. Cost 50
Humidifier (furniture) takes a furniture spot but covers the whole room and allows 1 - 4 plants to sit on top. Cost 400
Bathroom mirror, if placed in light, can reflect medium light further into the room. (Just for fun because I assumed it would have some kind of effect like that since it was a quest to get one. It wouldn't be more useful than a lamp)
Curtains can be placed over windows to soften or completely block light. (I know someone else said this but I thought of it too) Cost 150
Album to auto-save a pic of the plants we can eventually mulch. Could be furniture, item, or another tab next to inventory. (I might not need to keep every no star cactus I grow, but I do get sentimental) Cost 400
Mulch plants we don't want anymore, to get fertilizer that speeds the growing process of new plants (until they're adults/flowered) Could be a button next to 'stash' on the plant detail page. Fertilizer would be another currency, which you would apply to each new plant on their detail page. Cost 10 petals and a plant to make 1 fertilizer.
Sell plants we don't want anymore, to get leaves/petals. Either 2x buy price or 1/2 buy price, just depends if you wanna make it harder or easier lol.
Pot defaults. Option under settings to set pot color and style for each type of plant as default when buying new plants. (Someone else said this, I'm just seconding the motion)
Option to Auto set pot color to Max 🌟star🌟 level after study.
Super science desk. Furniture where you can destroy a plant to extract one of its star traits to stick into another plant. Limited by having to grow a new plant from that trait, so all else is random just like usual. Cost 1000. Could allow for growing multiple plants from the same trait. (Example: destroy a team player. Can now grow another team player a la nursery. As long as you don't destroy another plant for another trait, you can continue to grow team players) takes as long as studying.
If you add curtains to this game I'll donate $5