It is in the captain's lair which is under that hot vault. You get under there by using the robot to drop the crab full of cold water on top.
i am stuck
Get the right attachment named the " Living Quarters Key" and solve it with the steam battery.
there are 2 keys that i am aware of one under the crab then the other is in captain ziggs secret passage
The "crane" is a drawbridge that lowers to the right to reach the Botanical Research Lab. You will need the key to lower the bridge. (see related question)
You don't put it anywhere. Like the keys for Sully's and the Bridge control, you open the door using the Steam battery. You just need the key in order to use the Battery.
there no key for poptropica
The Greenhouse is part of the Botanical Research Laboratory (called the "production zone" on the map). It is across the bridge to the right of Main Stret and the Hub. You can only reach it by lowering the Bridge with the Steam Battery and the key from Captain Ziggs' quarters, at the top of the Hub.
you have to get the bridge key first and go to the production zone mix the herbicide 3bleu 2 green and 4 red put it on the plant and it will die then you get the key from the room behind it once you get the key go to the top floor and use the mallet to break the glass and get out
You return the key and the alarm will turn off and go get the mallet and come back and get the key.
You use the same Steam Battery to open the two doors (Sully, Living Quarters) and lower the bridge. But in each case you still need the key. Sully's key is in the Robot Crab, the Bridge Key is in Ziggs' room atop the Hub, and the Living Quarters key is (perversely) in a closet at the Research Lab all the way to the right of the island. Getting to it is more than half of the quest.(see the related questions)
You reach the Prodcution zone (a botanical research lab) by crossing the bridge from the Hub. The bridge key is the quarters of Captain Ziggs, on top of the Hub. Once you cross the bridge, climb the crane that has a wrecking ball attached. Push all three switches to the "down" position and the ball will crash through the weak spot on the ground below.
there is no key