Can I really throw failed PLA prints on compost? So they say PLA is biodegradable. But I still don't know how much biodegradable.

I live in a flat and we have composting trash can in the courtyard. However if I throw PLA in there and it does not decompose, neighbors are gonna be pissed since many of them are intending to use the soil for their balcony flowers.

So can I really compost PLA, or does "biodegradable" just mean it falls apart eventually, eg. in years? And if it decomposes, is it safe to use for plants?
This question has been asked on just about every forum out there.  Here's one example from filabot.com .


  The reality however, is that this process will take several hundred
  years in a typical landfill. To biodegrade, PLA requires a laundry
  list of conditions to effectively break down. Specifically - oxygen, a
  temperature of 140+ degrees *[Fahrenheit -- ed note] *, and a 2/3 cocktail of organic substrate.
  Collectively, these are absent in any scenario outside of industrial
  composting facilities.


I found similar comments -- tho' with perhaps slightly lower temperatures elsewhere.