two ways to think. in my mind ...

had it been earlier in the season.. a little shade for a recent transplant would be a plus ...

but i think.. in my z5.. winter heave is a bigger issue ...

i wouldnt want to find the plant heaved right out of the soil due to the freeze thaw cycles.. either in fall or early spring ...

i know we are in denial.. especially up here in the great white north z5 ... but we have frost coming in 6 weeks.. the garden is going down soon.. and i am betting with all the summer stresses... it will go down fast..

i guess i would suggest you simply cut down the tall stuff in front... so that sun gets to the soil for the transplants.. to encourage some good root growth.. so they can grab hold.. to avoid heave ... never forget.. in spring and fall.. its not air temps.. that are important.. to trigger spring growth or fall dormancy.. its SOIL TEMPS ... and soil in fall can get real cold.. real fast.. without the sun to warm it ...

i doubt you can harm an otherwise established perennial by cutting it down hard .. late in the season ...

ken

Thanks Ken for the post.

Last fall I put many nursery plants into the ground all the way from September into the first week of....November and as I recall not one went to 'plant heaven'. With a proper depth of hole and good quality mulch on top winter/spring heaving no longer scares me.

For sure a good suggestion to cut the tall stuff down in front except this Phlox is on its second bloom. I took this picture just today and although it is a washed out shot with the sun blaring down you can still get the jist that these are nice blooms and give good colour to this almost September garden.

Wow! Is that your 'Peppermint Twist'? I love it! It did grow up to be quite a robust beauty in your garden. Mine is so petite in comparison.

As for the kniphofia, I say go ahead and plant it as soon as you can. It will probably enjoy the extra shade from surrounding plants while it settles in and begins to send out new roots.

I usually have had excellent luck with fall planting. I planted a lot of perennials through November last year and all of them survived, although it was a warm fall. Still, I say go for it! If the kniphofia lives it will be much larger and more floriferous than a spring planted specimen.

cut them down.. when bloom is spent ... i surely wouldnt waste that show ... unless only to start cutting them to bring them in the house ... a few fronds at a time ...

if you want to avoid worrying about late plantings.. just add some loose mulch around the plantings.. at the last possible minute.. before your mulch freezes solid.. been there.. lol ..

i used to chop all the fallen leaves into fingernail size pieces ... and leave a big pile until around thxgvg ... and then apply it 4 to 6 inches deep on my soil. in my zone.. by spring it will settle to 3 to 4 inches.. and by june/july.. be nearly gone ....

its a blanket in cold zones.. so that once the soil freezes.. or nearly ... that sun doesnt hit it directly ...

my old fall back.. is GET IT DORMANT ... KEEP IT DORMANT ...

and by maintaining a dormant soil ... the plants will remain dormant ...

and the mulch will diffuse winter sun hitting the black soil.. and letting the soil thaw and freeze.. over and over .... thats where heave happens ....

do not cover the plant itself.. as you might suffocate it ... and that is the real key to small particle pieces on the mulch .. it allows water and air to move freely ... unlike intact maple leaves.. which can cause an anaerobic conditions.. where no air gets to the soil.. and you can suffocate roots ... [dont that too..lol]

then come spring.. the mulch ... slows soil thaw.. so the plants stay dormant a bit longer.. sometimes missing some of those frost/freezes and killing the plants ... and in doing such.. avoids the potential for the plants heaving out of the soil ...

ken