Hyacynths for early spring. Squill just after them. Hymenocallis in any damp spots and maybe some of the naked ladies (Lycoris?) or Amarcrinums for areas with a bit more light. Almost every bulb needs light to bloom well. The hyacynths get the most of it during the late winter before the trees leaf out but if your bed is in North shade that may not happen.

You could raise bulbs in pots out in the sunshine and move them into the shady area.

Otherwise - impatiens and torenia are reliable shade annuals.

Does your Abutilon megapotamicum get enough light to bloom?? if so, most other shade bloomers should do so.

Yes, I've used impatiens and they love it in there. The megapatomicum is near the front,... it sprawls and blooms like crazy and now that it's established it doesn't die back to the ground anymore. I use to have to whack it back and wait for new growth but now it's big enough it just keeps going. I try to plant the more light sensitive ferns to the west of some shrubs (steps and more bushes on the other side) and the ones that can take some light in the sunnier spots.

I've never figured out why since the previous owner/builders only used the yard to hit golfballs in but that bed is a weird sandy clay mix that holds moisture well. Even the astilbe thrives in it. About the only things I've had trouble growing there is elephant ears (too wet in winter/spring) and brugmansia which will eventually bloom but so late you don't get much of a show. Only the left side (of the steps) of that bed is like that and no were else in my yard has those conditions.

Leucojum 'Gravetye Giant' Colchicum, and Sternbergia bloom for me in dappled, mixed deciduous/pine shade.

Camellia Forest has heat-tolerant primulas that are doing well in my dappled shade beds. They come in some very vibrant colors so they really pop when they're blooming.

Sounds like a great spot for Turk's Cap lily! They love those conditions. I think Cypella coelestis would be happy in the front and Oriental lilies in the middle.

Allium nectarscordium (sp?) has done well for me in part shade. I second the summer snowflake leucojum- multiplies well and is magical. Also, strangely to me since it grows in sun in peru, scilla peruviana does super well for me in the fairly heavy and very dry shade of my getting pretty large bloodgood japanese maple. It's so happy they doubled from last year to this- they really like dry. I started with 3 bulbs prolly 6 or 7 years ago and now had 6 or 7 bloom spikes this spring (had always been 3-4 before). Stunning in bloom, but expensive per bulb. I'd also consider the english bluebells- scilla hyacintha, i think? The little hot pink/blue star in bottom species tulips i planted in the part shade did really well this year for their second year. I've tried other ones in part shade before and had less luck. Can't recall which one that is, sorry.