Cymbidiums need sun on their leaves to bloom well; deep shade culture is not conducive to this. They will grow and multiply in deep shade, but they won't set as many bloom spikes. The best blooms will result if you give them enough sun so that the foliage is not deep green; it should be more apple green colored. The flowers should easily last up to 3 or 4 months or more if you are growing them where the snails/slugs can't damage the flowers or buds, and they are protected from direct mid/afternoon sun and rain. I find they last the longest on an east facing porch under cover from the rains. In such spots with just a little care, I've had them continue to look great in bloom for up to 6 months. I'd also suggest that you fertilize with a good general liquid feed monthly once they finish blooming.

Peggie, I have the same color cymbidium in a shady spot in my side yard. It has already bloomed and I cut it to enjoy it in the house.
Lamium maculatum grows in the shade. It spreads, though. There's a variegated liriope which lives in shade as well- it may look similar to your dianella. My favorite shade flower is cyclamen. I look for ones with dramatically variegated leaves. They bloom at the same time as your orchids, so choose colors accordingly. If you want a contrasting leaf shape, hellebores are nice and they bloom early too.
Renee

So you were looking for other recommendations for something to brighten up deep shade? Some things I like to use would include Carex oshimensis 'Evergold', Carex baccans, Acorus gramineus 'Ogon', Aucuba japonica variegata, Musschia wollastonii, Brunnera macrophylla 'Jack Frost', Bergenia, Clivia miniata and Clivia nobilis, Dianella intermedia and D. ensifolia, some Abutilon hybrids and Neomarica caerulea. All of these either have colorful foliage, colorful berries/seeds or flowers and do quite well without much sun at all.

I didn't realize that Muschia did well in shade. Good to know.

I'm not sure orchids like to be crowded with other plants. They don't have to be divided, and they don't mind if their roots are crowded in a pot, but I don't think they like competition from too many other plants.
Renee

These Cyms are being sold at HD for a relatively low price as part of a "super promo." Usually they hover around $30~40 if I recall correctly. But they're all $15 now and most of them are very lush and some of them have multiple spikes.

Here's one I picked up on Saturday, with the tacky wrapping/decor removed. I picked one with unopened buds for a surprise, I couldn't decide on red, green, or yellow flowers hehe. Hopefully it's a fragrant variety like Golden Elf.

I wonder what nursery is supplying these to HD?

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I would like to know what they do to cause flower spikes on such a young plant? Al

They grow them in precise conditions in glass houses with artificial lighting and optimal temperatures, and push them with fertilizers to bloom young. Orchid cultivation is exacting and very scientifically well researched. Plants are tissue-cultured clones and all that.

The shade garden is on the south east side of the house in a corner. I have two 23 year old Japanese maples that dominate the garden. I trim both after they leaf out to let in light and allow for a view. My cymbidium may get some reflected light from a stationary panel of a sliding glass door. Thank you bahia for pointing out sun requirements. Getting those shade plants positions on the knife edge between burning up in the valley floor and too dark too bloom is an art. I do usually fertilize monthly when there is hope of results. Sometimes in July I lose all hope and the garden goes on auto.
Some of the new cymbidiums were to go under the redwood that yesterday we paid to have murdered. The remains make a huge pile of mulch in the driveway. I told my DH for years it was too close to the house. At 65 ft he finally decided I was right lol! So I will have to look around for more knife edge shade.
I am a fan of lamium, hosenemiesis. It's easy to steal some cuttings and give it a try in a pot. I really like how it cascades. Liriope and Carex oshimensis 'Evergold sound beautiful. My established cymbidium has very brown Japanese forest grass in it's pot. It will be green by the time the cymbidium blooms ripen but I am moving it out when I repot later. Tufts of brown grass look good with naked little J maples for winter interest but not as good with the evergreen leafed cymbidium.
Thanks for all the good ideas. Even if I don't put your suggestions in the pots they are certainly good ideas for the garden.