Spring Planting Questions - HELP!!!

OK, so last fall we bought this place with great potential, but I'm starting from scratch. New construction, so all my good soil is gone within 60 feet of the house - I know I have a chore ahead in ammending. We rarely dip into the teens in our deepest winter, zone 8 or 9 depending on whose zone map you're looking at (Southern Puget Sound, WA). Yesterday was our second major purchase of bulbs and tubers. The first was the obligatory (in my opinion) fall planting of tulips, crocuses and hyacinth. My question and caution lies in when to plant this new batch.
The elephant ears say they need to be brought inside for winter. I figure I'll probably get them started inside in pots to give them a jump, then move them outside late March or early April.
The Acidanthera, Gladioli, Cannas, Fresias and Double Tuberose all have a generic statement, from the same packager, that they shouldn't be planted until the ground is 50F. That could be late April or May.
But there's no guidance at all on the Astilbe, Caladium, Oriental Hybrid Lilies, Dahlias, Peonies, Bleeding Hearts, Lilies of the Valley, Tigridia, Calla Lilies or Red Trillium.
We have plenty of wild White Trillium in our woods but I wasn't sure if the Red was a more sensitive hybrid.
And the Dahlia packages say to plant two inches deep, yet we brought a good quantity of Dahlias from our old place and were able to talk directly with the grower of those who said to plant all Dahlias six inches deep. Those transfered plants have done well and these new tubers are of the same plant height variety - about 24-30". ???
Our only lawn is a pathetic little patch the builder put in, but in truth, I'd prefer to have as much in low maintenance gardens as possible in place of trudging behind a mower every day off I get. Our house sits on about 3/4 acre which dips down to a small salmon stream and continues for the rest of our three acres. The rest of the property is inaccessible except by foot. Probably about 1/4 acre is pretty boggy, currently filled with Devil's Club. I have 17 Gunnera thriving, and 5 struggling, in a cold frame I got as seedlings off of eBay. Also bought an established 1 Gal Gunnera and put it down by the stream. Everything I could find said Gunnera were very pest resistant - but I'm here to tell you our Northwest slugs like them. I'l plant some of the Gunneras and probably trade the rest.
The fact I have a salmon stream running through my property is not something I take lightly. I plan to follow the standard recommendations - avoid chemicals, stop motor oil leaks, avoid phosphates put into our septic, etc. But one area that is difficult, at best, is trying to find out if a plant is potentially harmful to a stream. Everyone knows there are plenty of plants, mostly trees, that are prohibitive to the growth of others. Cedar, Walnuts and Holly come to mind off the top of my head. I just don't want to plant anything non-native that might thrive yet be harmful to the stream.
I want to put a small bridge over the stream with paths through the woods and gorgeous foliage everywhere. All suggestions welcome!
Thank You, Dave, for creating this wonderful site!
And thanks in advance to all in the DG gang that takes the time to respond to my ramblings. - Brad

Welcome Brad! Let's see if I can offer some assistance....................
Dahlia: Plant mid April in good draining sunny locations (I leave mine in the ground all year)
Astilbe: Plant April 1stish again in good sunny to part sun local....great perennial here in the PNW
Lillies: Plant late March early April, full sun, good drainage (leave in...no need to dig and store)
Peonies: Plant now, careful to not bury the crown to deep.....good sunny local. Great perennial here.
Bleeding Heart: Late March early April....hit and miss as a perennial here, rots easily if to wet.
Lily of the Valley: Plant whenever you'd like....part shade. Spreads quickly when happy.
Calla Lilies: Moist soil location, fair amount of sun....wonderful perennial
I haven't grown Tigridia, or Red Trillium so can't offer any help with those......all the others are real troopers in my garden beds.

RikerBear
Marc
Seattle, WA

Thanks a bunch, RikerBear! Will the Calla Lilies do OK with more limited sun??? I'm thinking of having them as little splashes of color in my woods. We have the pink variety. - Brad

My heirloom white do great under the over hang of our deck.....filtered light most of the day. I can not speak to the habits of the 'colored' varieties, but can only assume the would be similar

Marc