A320
Flight Crew Instrument; Flight Crew Multiengine; Flight Crew Air Transport Pilot (ATP)
Distraction; Situational Awareness
Deviation - Speed All Types; Deviation / Discrepancy - Procedural Published Material / Policy
Flight Crew Became Reoriented
Environment - Non Weather Related; Human Factors
On departure I noticed that the airplane was climbing slowly; and realized that the landing gear was down; I then requested that the gear be brought up. The gear was retracted at 218 KIAS and in the retraction process the aircraft exceeded the gear retraction speed.  Although the over speed was not known at the time.  It was not until I was notified by my company that I became aware. I am not entirely sure what distracted us; although I have a strong feeling that it was related to wake turbulence avoidance.
A320 First Officer reported flight crew forgot to retract the landing gear; probably because of wake turbulence distraction.