Minnesota zn 3/4 here..6 weeks out from hard frost you can plant anything including hosta--especially hosta. That should give you plenty of time.

the deeper you get into fall .... the more i would be more concerned about late winter or spring heave.. rather than whether they can be planted ...

there are many variables on such.. like native soil [how able they are to settle and grab hold] ..... how planted [bare root] ... how big they are at planting [are they heavy enough not to pop out... a mini H issue] ... ground freeze [continuous all winter] .. and snow cover [get them dormant.. keep them dormant] .....etc ...

all that could be handled .. again.. late in the season .. with a good late heavy application of mulch ... just after the ground freezes ...

of course.. you could also keep them in the pots all winter ... but thats a different process ... north side of house.. tipped on side .. etc ...

this is VERY ZONE SPECIFIC ...

ken

I am in Ontario (zone 4) and have never had a problem planting hostas in fall. Hard frosts can occur in mid-late September but up until mid September all goes well.

Late in the season I do not bare root any hosta. Planting it from a nursery pot I try not to disturb the soil and simply plunk the whole thing in the ground after removal from the pot.

We have very reliable (way too reliable when it comes to shovelling) snow cover and the ground once frozen and snow covered rarely exhibits freeze thaw cycles.

Regards ... Doug

Doug Matheson

Manotick ON

I plant until the ground freezes and have planted several hundred hostas at that time of year. Ground heave is not a big problem if you have sufficient snow cover.

Dividing is a different matter and generally I like to finish that by the end of August to give the plants time to settle in their pots.

In my zone 5 garden in Vermont I planted as late as October 31 with great results.

I have no cut off time on purchasing plants marked down by 50%. You can heel the plants in, pot and all if you like, and deal with them in the spring. I've never lost any doing this.

I haven't experienced much heave, but I've had squirrels / chippies dig up my small plants in the fall / spring. I've learned to put rocks around smaller plants that are not yet well established to discourage this and it seems to work. It also helps me to recall where I've planted them... I would think this would work for heave as well...