IMHO none now. I usually fertilize through about the beginning or mid-July at latest,no more. Best not to encourage new growth. Maybe a very dilute organic fertilizer would be fine but nothing to jump start it.

definitely no time release .... we need to have the plants slowing down by october.. not all juiced up on fert ....

a little bit of this or that should be fine ... as you have at least 2 months of soil warm enough for root growth ...

but by the time they are going dormant.. i question that there would be any value to fert ...

your best bet.. might just be to skip it ... save it for late may next year ... [based on our z5]

Could not upload yesterday ,darn Houzz.

ThIs is my concern

I fertilized just this weekend. My hostas are just blooming now, so I give them a good dose while they are in bloom and that will be it for the season. I do the Miracle grow dry stuff in the hose attachment kit. I am in zone 4 and my growing season is very short compared to the majority on this site. It works for me, but the fall is in the air in my neck of the woods. :(

I'm not sure if applicable but maybe just an iron supplement. Espoma Iron-tone perhaps?