How often should a piano be tuned?
Within a domestic environment, every 6 months.

Why tune it when its not being played?
Playing a piano does not effect the tuning. Change in climate, humidity, and tension of the strings slowly moves the tuning.

These strings will probably last another 30 years.

What about moving it?
Moving your piano into another room to have the carpet fitted?, no need to re-tune it.
Move it to another home where the climate and humidity invariably are different, we recommend tuning after a 2 week settle period.
The moving of a piano, if done professionally, will not effect the tuning. It's the change in the environment.

Why does our piano not hold its tune?
Two reasons mainly, the room it's in is getting too hot or the tuning pins are too loose, the latter needs your tuners assistance.

Tune to Concert Pitch Mr Beethoven?
At Concert Pitch the piano will be in tune with other instruments.
If not tuned regularly, it will drop in pitch and may be tuned flat, in tune with itself only.