Walking from the top of King Edward park you find Estufa fria on the right side of the down hill. The entrance is very cheap (3.1 euro) and you get to enter in a big greenhouse with cold (the main one), hot (tropical) and sweet (cactus and palmas) ambients.
Warmly suggested a visit to this place, as it's relaxing and nice to see and wander around being a big complex.
You don't need to be an expert of plant species to appreciate the beauty of nature.
I'd have liked anyway a map or some explanation of the different plants (paying of course, as the entrace price is very low).