its probably going to have to be something you just try ... how in the world would we know ..

it appears to me.. the canopy is raised high enough.. that there is a lot of ambient light.. even though it might not be direct light... which would be a good sign ... whats growing there other than the trees to give us an idea???

the usual problem with gardening under large trees.. is the trees are super competitors for available water ... you mention 2 systems watering the area ... but how deep does the moisture run >>.. i would go dig a 12 to 15 inch hole.. AND FIND OUT... if you are getting water deep enough for a clem ... repeated surface wetting may not be good enough ... and of course.. you need to find out in the heat of summer.. not winter ... when moisture is not being drawn from deep int eh soil .. the alternative.. is to insure deep watering in july and august.. aka.. the heat of summer ... and a few weeks either way.. since is dont really know SC ...

if you dig a hole under a large tree.. and then fert in that hole.. dont be surprised when the tree grow roots in the hole you dug, watered and fert;'d... so when you do plant.. try to trick the tree by not doing such ... broadcast water.. skip fert until your plants shows you it needs fert ...

just give it a go ...

ken

Won't be happy in mostly shade.....few clematis will. Growth will be slow and flowering sparse. And as noted, root competition from established trees of any type make it quite tricky to plant and establish a clematis under the described conditions.

Go ahead and try it.........but don't expect resounding success.

You may get more helpful feedback if you were to post this in the Clematis forum as well

I have a clematis growing under a large hawthorn. Mine is one of the wildlings - flammula or ternifolia (?) or such. Anyway, what happens is it takes about 6 years to fight its way through the hawthorn, to some sort of light and then you can only see it from across the fields on the other side of the road. However, even for all that, I am glad we planted it - I think it has wildlife value and yep, it does look lovely, like a cloud of late anomalous blosson erupting through the foliage. I think you need a vigorous variety too - not Nelly Moser, tbh. SAC, or maybe an armandii or montana.

Thank you for your suggestions!

Planting site is pretty prominent. And large flowered deciduous hybrid clematis look trashy in winter - how about something like star jasmine instead?

Ah, I also grow a very vigorous evergreen cirrhosa (flowering now) and have also had another vigorous late flowerer - rehederiana...both of which reach 6m and more, given time to establish - we have never watered ours so it can be slow, but doable if you consider the smaller flowered and less colourful species. No, you won't really be seeing many of the flowers from underneath the magnolias. Only a couple of gnarly, single trunks are visible at ground level - but up in the crown of the tree, a clematis can add an extra element and will, I hope, begin to cascade further out of the crown of the tree as a framework of flowering vines gains enough light.