First and foremost for this achievement you will need to make a Cocoadile your resident.
To get this you will need to transform a Sour Cocoadile into a normal one, to do this you will need to meet these requirements:
-Be a Level 28 gardener
-Eaten 1 Sweetooth (Level 21 gardener, 14% water, eaten 3 fir cones, eaten 2 water lily flowers to become a resident)
-Eaten 1 (or some have reported 2) Swanana (Level 27 gardener, garden worth 20,000 CC, 25% water, eaten 2 sandwiches to become a resident)
Once it has done that it will go into a cocoon then it will hatch into a regular Cocoadile. Now plant a simple plant (tulip for example) then select the Cocoadile and direct it to the plant. It will then cry on it and you will get the achievement.