That's the theory, anyway.    Just figured I'd try it and see how it goes.

I think that they can be harvested at the earliest at three months, are fully matured at six months, but can continue growing and becoming more potent for many months after that.  I have heard numbers of nine months to a year should be OK.  (I think that's from Violet's tek.)

Mine were finally harvested at eight months, and I'm pretty sure they were still growing at that point.  There was definitely uneaten grain left in there.  (The centers had plenty of unused grain.  All the remains are sitting in a bucket as a side experiment right now.)  That batch was multispore though, so maybe the slowness is why it was still going and not done.

That sounds wonderful!  I *would* say to crack open only one of them, to allow the rest to continue growing, but I found out the hard way that this is not a good idea.  The stones have random potency, or at least mine did.  First trip underpowered, second trip overpowered...  Had to harvest them all and grind them up to standardize the potency for proper dosing.  (So far so good btw, I haven't written about that yet.)

I recommend being patient, at the very least so that you can standardize.  But you can be brave and see how it goes, which would be adventurous.