Answer: Although year round bloom would be the ideal, it is difficult to achieve in practice with a fairly severe four season climate. You could plant seasonal mums and asters for fall color along with pansies and violas, these last two will rebloom in the early spring. The earliest spring bulbs for me have been snowdrops, Iris reticulata, and snow crocus along with February Gold narcissus.
Tricyrtis is a lovely fall blooming perennial for shade and you might enjoy the late blooming hardy begonia, Begonia grandis; the hardy Cyclamen hederifolium is great for fall flowers and then gorgeous foliage into the winter. Then Hellebores will bloom very early -- hence the name Lenten rose for some -- and are also shade lovers.
In the fall, the large shrub Hamamelis virginiana blooms in October. I can't think of anything specifically flowering for November -- this is the month when most of the fruits and berries become really evident such as Callicarpa, Aronia, and Crabapples and you may still have a stray rose or two. For bloom in December and January the list is also pretty short. The best I can suggest is Witchhazel shrubs -- Hamamelis vernalis usually is in bloom for my birthday in late December and continues off and on until February. The hybrid witchhazels then begin to bloom and cover a long period. Sometimes the rather weedy, sprawling,yellow flowered Jasminum nudiflorum will bloom during warm spells in February. Cornus mas might also be something to consider along with Pieris japonica and Chaenomeles for March.
You can also force some Paperwhites and Amaryllis to enjoy indoors on the windowsill whenever, neither of these requires a chill or pretreatment to bloom.
I hope this gives you some ideas.
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