Euphorbia robbie, maybe epimediums. I bet gardengal48 can come up with a few more. That is a tough area to grow much of anything well.

Vancouveria, Oxalis oregana, Trilliums....

Some native plants would be able to grow there like Salal, and Oregon Holly Grape. I got tired of weeding and started some invasives. Don't plan on changing your mind easily after you plant these.
Vinca major- gets a couple of feet tall after a while and really fills in. blooms in spring, shiny evergreen leaves, variegated forms available,
Vinca minor- trails on the ground, blooms in spring, variegated foliage looks great in shade,
Groundcover Comfrey- very hard to eradicate, fuzzy leaves, blooms in spring, can survive without supplemental water,
Geranium macrorrhizum- tough, blooms pink in summer, little or no water,

Lovely plants not invasive-
Anemone nemarosa- choice tubers, grows and blooms in spring, enchanting patches of flowers and tiny foliage 3" tall, goes dormant in summer so needs no supplemental water,
Pulmonaria- blooms in spring, pink, white, cobalt blue fading pink, purple, various patterns of silvery variegation, tough needing little water in summer, self-sows, nice foliage plant in summer and fall when not in bloom,
Helleborus orientalis- early spring bloom, some supplemental watering needed, self-sows.

For a low evergreen, try Lonicera pileata, or privet honeysuckle. This seems to tolerate the root competition of pines as well as anything. Also successfull for me have been Geranium macrorhizum, Luzula sylvatica (Wood Rush- both the golden and variegated forms) and sword fern.

Good suggestions so far (although the hellebore would be far happier in less competitive and brighter surroundings).

Also:
Iris foetidissima
Dicentra formosa and eximia
Hardy fuchsias
Geranium phaeum
Lamium
lady's mantle (Alchemilla mollis)
dwarf Sarcococca (S. hookeriana var. humilis)
Brunnera
Fringecup (Tellima grandiflora)
vanilla leaf (Achlys trphylla)
snowberry
huckleberry

I have half of Gardengal's list plus multiple Pieris and dwarf Rhodies in dry shade caused by mature Doug Firs and other conifers. Huecheras and 'Toffee Twist' Carex too

Thank you everyone for your suggestions! I'm excited to go looking for some plants this weekend! I think I will definitely try some lamium, huckleberry and brunnera and am bringing the other suggestions with me in case I find any others I must have.

buyorsell888, is your Pieris right under the trees? I just bought a beauty and am wondering if it can compete with the roots of my cedar trees.

Yes, the trunks of the neighbor's trees are about 8 feet from the Pieris. The branches of the trees extend much farther than that. The neighbors planted a row of conifers along their fence back in the 50's and since my house is to the South, the branches of the trees are all longer on my side. Some are twenty feet long.

I do have soaker hoses in that bed, the Pieris are not as big as they would be without the root competition and shade but for me that is a plus.

I believe they are Mountain Fire and Forest Flame. I also have Cavatine which is a dwarf, it is new but the other two have been under these trees for over ten years.

I also have Valley Valentine 3 feet from a mature Arborvitae hedge. It was a scraggly rescue and isn't the nicest looking Pieris but it does bloom and grow and has for ten years. Also soaker hosed. The trees really suck water.

Good to hear all of these suggestions! I have found it fairly easy to grow thing close to the tree itself. It's when I get out closer to the drip-line that I have problems!

I would add to the list the Epimediums. They do well in shady, dry places.

jb

jb, they were one of the first plants mentioned :-) Wonderful and rather underused plants for dry shade or really for any shady location. My collection is just coming into full flower now.

My only try at Epimediums was a nice reddish one that got smaller and smaller as the years went by and finally disapeared.

Ha ha at jb :(. Damn I missed that.

We have several and they are doing well, but no blooms yet. We are a few weeks behind the Seattle area.

I wodner why yours dwindled? They are such hardy plants that require almost no attention. You must have a special skill. :)

jb

Many mentioned above could fail in many locations, starting with serious limitation of substantial and recurring weevil damage likely under low-branching conifers. You can't generalize too much, provide absolute assurances. What makes it in a particular spot depends on total combination of conditions, including density of trees, soil composition, irrigation practices...try looking around neighborhood for similar situations and seeing what looks good there.

My experience is that hardy Fuchsias don't make it with that kind of shade and root competition, nor hostas. Vinca is bad-mouthed but makes a stunning surround to a cedar and looks impeccable yearround. Of course it is best alone as it will run over everything else. Mine seems to stop at the edge of the shade. I have too many large cedars to be fussing around with delicate plants and another place to weed. Same for the groundcover Comfrey being tougher than weeds and filling in, and looking good even in summer. I have a large bed with different perennials within 10-20' of cedars but not directly underneath.

Lesser periwinkle should be great to use in numerous ways here - if it didn't have a tendency to make smothering ivy-like carpets in the woods.

Cedars in particular do have a tendency to branch very low and that does complicate the issue - far less light and direct rainfall. Groundcovers may indeed be best for sitautions like that. OTOH, conifers which branch higher or can be successfully and attractively limbed up (Doug firs, hemlocks) widen the opportunties.

No one said any of these were sure-fire solutions. It will depend on specific situations and the ability of the gardener to tend to these plants during their period of establishment, but all of the aforementioned plants (maybe excepting pieris and rhodies, that need additional fussing) are well-adapted to the dry shade situations present with adjacent conifers and technically (and in many cases, practically) will work.

If pieris and rhodies are doing well a location is apparently not really that dry. Both require moisture. It does seem many under-watered plantings here skate by on our cool summers. But pieris is a feature of places like Yaku Island in Japan (home of Rhododendron metternichii yakushimanum) where it rains feet each summer. In fact, it is said to poison mountain streams there! And weevils, which appear to display a definite extra ferocity under evergreen plants and building overhangs, are somehow not a serious factor if a planting in "dry shade" is not being turned to confetti.

Wonderful suggestions here. I'd like to but-in with my own related question: I have a north-facing yard, three LARGE cedars on the East side, limbed up about 15 feet. I'd love to plant hostas, convalaria, astilbe, solomon's seal, trillium, sword fern, (lots of that!), toad lily. I can wet the ground as much as I need to with soaker hoses, but what about the light level. I haven't moved in yet (take possession in a month), so not exactly sure where and when the light hits. I'm thinking part shade, with the height that the trees are limbed, but ...

Love your suggestion. Love this forum!

Janet

I have sword ferns right under red cedars with no problem, and trilliums in various very shady locations. I haven't succeeded with hostas under trees but didn't use soaker hoses either. Toad lilies I killed, so I consider them a difficult plant. My native low-growing Oregon Holly Grapes do well under trees and in dense shade. They flower and have edible berries as well. They have nice shiny evergreen foliage too.

My sweet little three year old deer fern are dying under the cedar. I have been told that shade isn't the only problem with cedar. Seems cedar itself is toxic to certain plants. Is that a significant issue?
What grows like crazy under mine is wild ginger which planted itself, bleeding heart, and self planted sword ferns. I did not want the sword ferns because they are not evergreen so I purchased some autumn ferns and the deer ferns. I have some struggling rhodes on one end of the bench that gets more sun. They did well for several years, but I do not fully understand their struggles which seemed to have started two years ago when their leaves were nearly destroyed by what I think may have been some type of beetle. Last year the leaves were not touched, and the plants seemed to recover though the flowers were sparse and small. I feed them but maybe not often enough. They are small rhodes and were beautiful in their place until they sharply declined.

There is a "tail" area on the shadiest bench that gets lots of sun but every plant I have put there has died. It is almost as if there is something toxic in that soil. I am about to put landscape cloth and river rocks there and call it good enough.

Any suggestions for me? I want to purchase a new rhode, but am somewhat reluctant until I grow to understand what happened to the existing plants.