Your understanding is pretty much spot on.

if you fert late.. and your plant goes into a vegetative growth phase ... just as its freezing to the ground.. in the great white north ...

then odds are.. your plant will .. or i should say.. has the potential to ... turn to mush as it freezes ... or mush come spring ... crown rot ...

another way of saying it is... it wont properly slow down toward dormancy ...

i have no experience outside MI ... so no clue.. how that all works.. the warmer the zone ...

besides.. they all started growing roots in july or so.. to store energy.. for next spring.. by fall.. one might argue.. the job is done.. so why waste fert??? .. if you wanted to have an impact.. you missed the boat by 2 or 3 months ...

ken

I am with mikgag here in Canada. My dad always use to tell me to avoid fertilizing after mid July, unless the weather has been unusually warm, then at the latest very early August. I don't know if he knew the science behind this, but I suspect Ken is bang on that late fertilizing leads to interference with the normal progression into dormancy, and makes little sense in terms of normal root development times. Biggest bang for the buck is definitely in spring, just as the pips are emerging.

Though when just planting 14 hostas I mixed some compost, bone meal and manure in each hole to give them a good start - but no 10-10-10.

Bernd, good to know that's OK because I've been doing that when transplanting or adding new acquisitions in September.

It depends on where you are. If you're in zone 5, ken is right. My hosta don't go down until November, depending on the first hard freeze. We usually do our last fertilizing between September 1 and September 15.

bk

Would the use of epsom salt be considered a nono this late as well? Just curious

houze won't let me paste any urls, or I'd point you to good reading. B4 dismissing late season fertilizer, I suggest you google that. The real, educated experts out there have good research. fwiw