I think you'll just have to let the plants do their thing. The spears that come up while you're gone will start to fern and won't be edible, so you should leave them there. New spears will probably keep coming, even so.

Sorry but it starts you can't delay them. Just let them go to fern unless you can find someone to harvest for you while away.

Dave

I kind of thought that. Once they start, I guess its game on. Thanks for your replies.
I might conduct an experiment tho, if I have time before I leave town. Will let you know if I do.