Pots of summer colour in partial shade

I haven't got around to the planned big tree chop this autumn/winter AGAIN so was hoping for some help with getting some summer colour in the shady bit of my garden - it needs to flower for ages - perhaps something tender or half-hardy - but the shade is enough that even last years' snapdragons struggled to show much after their first flush. Anyone had any success with anything they've grown from seed? I've tried any likely garden-centre candidates ready-grown - the usually available suspects are all too sun loving. The area in question does get late afternoon/evening sun directly, but only the dappled light from between trees for the bulk of the day. I could do with using long-tom pots for height (its for colour between small-med shrubs) so nothing that wants super-cool/wet roots please...? And preferably upright rather than trailing, though beggar's can't be choosers.  I know, its a big ask!!! Just hoping someone out there can provide me with a brain-wave. Had considered some of the plainer fuschias but reluctant to risk the expense without someone else's say-so.  Bx

I grew some 'pixie' lupins last year, they are only annuals but they bloomed right through till winter. My snap dragon, 'bunny rabbits' are still blooming, if you want something trouble free and long flowering these would be the ones again for me.
You do need to dead head all annuals to keep then flowering and a drop of tomorite will help.
There are some fuchsia s that thrive in shade, but a lot like heads in sun, feet in shade,

You can't beat busy lizzies for shade. They flower all summer. Since there is a disease issue with the normal ones I would plump for the New Guinea varieties. Get them soon as plugs and pot on ASAP and, ideally, pot on again before plantIng out. They have brilliant foliage colour too. Why not plant a couple of ferns in there too? Perennials like liriope.....grass like foliage and short purple flowers in autumn....Astilbes, hellebores and Astrantias will add a perennial feel. A white hydrangea for impact and "weight" and you have the makings of a very attractive border