Which sources do you trust?

I've always relied on Sunset Western Garden Book (Sunset Zone 24, USDA Zone 10b). Now I may be doing too much research because the zone designations from the "experts" don't match up with Sunset. Sunset tells me I can have the plantigenea hostas but other sources say no. Brunnera, zones 5-8, but Sunset tells me they're good to go in my zone. I'm a little confused, here. So what's a girl to do? Who do you trust? TIA, Syb

Published zone ratings are notoriously inaccurate, though I suppose only people living in areas that would be at the more extreme ends of the scale would realize that. For example, your source that says Brunnera spp. are only hardy down to zone 5 is horribly wrong... but then you already knew that. ;-)
Here at the cold end of things, it's best to ignore zone ratings and simply find out about hardiness by growing whatever interests you. However, with a much larger population (read "commercial base for plant sales") existing in your end of the spectrum of horticulture zones, I'm sure there is a great deal more information available, some of which is probably reliable.

I would try the plantiginea hostas. I find Sunset to be quite good, but there are some things that will grow here that even they don't know about!
One thing is to look right here in DG PlantFiles, if you scroll down the info about a specific plant, DGers have inputted if they can grow it. This really is helpful for me-if there are a few listings in the Seattle area I am likely looking at a plant that can be hardy here, whatever the books say. The way the listing is made, you have to click on a link to make it the full list if there are more than a few entries.
Note it is a list which can be inaccurate- if an inexperienced gardener entered that they grow Petunias in Seattle, then it will say Petunias are hardy here, when all it meant was that person grows them in Summer as an annual and did not really understand the list.

You may find the DG info helpful but it is also often compromised by the fact that hardiness info is entered by a single member, based on whatever they have chosen to believe is a correct zone range, which would often be coming from whatever they've read in a book or, more often now, found repeated on various internet info or catalogue sites. (Hardly anyone has had experience gardening for long enough, across a wide enough range of zones including the extreme ones, to be entering first hand info into the zone range field.) So, zone info at DG often has the same bias as that published widely (since it's often from those same flawed sources). The zone info entry is then "locked down" and for someone else to come along and correct this info to say, for example, that Brunnera macrophylla is actually hardy at least down to zone 2, means asking an administrator to make a correction. For thoroughness, this would mean not just one correction, but to go through all the various cutlivars of that species and to request as many corrections as needed. To do this for hundreds of species, such as a keen gardener would have experience with, is no trivial feat.
(NB. I have actually spent a lot of time and effort at trying to correct zone ratings in the DG data files to match my personal experience and knowledge of what grows in colder zones, and it's too much - I have basically given up. Yet, I'm looking right now at the entries for the genus Salvia in DG and see dozens of species/cultivars for which the entry for the lower end of the zone range is wrong.... an extreme example is Salvia verticillata 'Purple Rain', which has overwintered successfully here in zone 3 since 2005; the zone rating in DG is "7 - 10". Most examples are much less extreme but would still make dissuade someone in zone 2 or 3 from growing a species that would be perfectly hardy there.)
As I already implied, inaccuracy of zone ratings is probably a bigger deal at the cold end of the range than at the warm end, though. You might find the zip code info in DG to be useful, particularly.

Hi alta-
I agree with you about the Hardiness Ratings, both here and elsewhere. What I do find helpful is the "Regional" Heading found below there in the plant entry. This is where DGers can give a "zipcode report" if they find a plant hardy where they live. I find if there are even two reports from my area (Seattle) the plant is worth trying. Even if someone could fix all the Hardiness Zone ratings (thank you for trying), since both Seattle, WA and Dallas, TX are zone 8 it isn't always helpful anyway. We all know they are completely different climates.
I was excited about the AHS Heat Zone map when it came out, but the few things I checked the map was wrong about. Even in the very local setting, it varies a lot. I moved two miles, from a house on beach sand by the lake, where Penstemons and Salvias thrived, to a clay slope where hardly any plants like that will survive our soggy winters. The Zipcode reports do help me.
Sybil may want to check out the heat zone map, but it isn't used much yet, so there aren't all that many plants rated for this.

Thank you everybody. It's just as I thought -- I'm not the only one confused by zone designations. The only thing we have to worry about here is not enough winter cold for some plants, hence the bulbs in the frig. I will definitely try the hostas because I've always wanted to, even if I have to treat them like annuals, and I know this is heresy to true hosta lovers, but I've got this little rock garden scene in mind and if I can get the tiny ones for less than $10 they will certainly be happy through spring, summer and early fall (whenever that is). Its hard for a lot of people who have winter to understand, but many plants that are not "hardy" in most zones bloom all year round here - cyclamen, tuberous begonias, etc., because they are waiting for the first frost which never comes. I finally figured that out. Roses are blooming all over the place, among other things. Maybe the plants are just as confused as we are. Glad to know I'm not alone out here. I'll try those things with the library DG, but it usually doesn't work for me - gives me no results at all - maybe with this laptop it'll be different. Thanks again, Syb

Syb- I hope you will put in your "zipcode reports" of what you find to be hardy in your garden, to help the next person decide what to try-this is why this site is so useful, tons of folks contributing, from all over.
On another note, I have found it really pays to find gardening books and websites about gardening in the Pacific Northwest, also to go to local Botanical Garden and see what is growing there. Usually there is a shop that has a nice selection of books about local gardening, and often is staffed by a volunteer with good knowledge about the books.
I just had a thought and looked at a map-the Huntington Botanical Garden is famous, and not too far from you (I noticed the name was the same). Wow I would love to see it. I will bet they have a really nice shop...

Huntington Gardens is inland so it has a very different climate then Huntington Beach. I was at the Bontanical Gardens in the Summer of 2014 it is beautiful but the gift shop is really small, I was surprised,I remember ir being bigger. There is a fantastic art collection too and they serve High Tea.

There is also the LA County Arboratum.

The USDA zones are for cold not heat and within there, there are a lot of microclimates. Sybil's zone is 10b not bc of how hot it gets but bc it rarely gets really cold or really hot and it's at the beach, which makes it beautiful.

I think almost anything will grow there. I grew tons of different things in the San Fernando Valley, then I moved to Texas.....lol

1. I've figured out how to work the plant library, and will enter 10b stuff as soon as I know anything, since I'm in the first season of my newest start-from-scratch garden.

2. In this zone - Sunset 24, 10b, the arboretum is the Sherman Gardens in Corona del Mar, also 24/10b. Its right on Pacific Coast Highway in the coastal zone. They have collections from everywhere. syb

Syb: One impt. thing you have to remember is that here in So. Cal. we have a plethora of "micro climates". What may grow well for you in HB "may" not grow well for me here in LB for a variety of reasons...i.e. we get frost here in 10a and are usually hotter in summer than where you are.
I'm 5 blocks from the ocean and many things freeze for me in a "normal winter" which don't suffer at all for a friend of mine who lives 3 miles inland from the ocean in Huntington.
Brunnera works here if treated as an annual but never really reaches it's potential. The summer heat fries it. OTOH I can grow Phlox paniculata and it performs very well...she can't grow it where she is.
Like many places, gardening in So. Cal. is a trial and error basis. Our weather is so inconsistent lately.

As an aside, you can leave daffodil bulbs in the ground year round here (and where you are). They don't need refrigeration to bloom...assuming you purchased the ones for warm winter climates.

Years ago I found a 4" pot of spent red tulips in the dumpster. Just to see what would happen, I planted them in the coldest shadiest spot in my garden and they've sprouted and bloomed without being dug up and refrigerated for the past 10 years. Go figure !

Hi, JasperDale, I lived in Long Beach for a long time, and I do remember the frost. Moving everything into the garage and covering up the rest, wondering if I'd get done before I froze to death along with the plants. Well, the bulbs came from Brent and Becky's and when I asked about the chilling they recommended four to six weeks, and another source said twelve to sixteen. And, like you I've also heard no chilling necessary. I don't want them coming up early because of The Plan (yes, I hear the Gods laughing). I've got some other things I need to bring along, trying to get the whole meal on the table at the same time. My "really good idea" is a Gauguin Gallery, based on his kitchen in Provence, before he went all Polynesian. It was blue and yellow. Hopefully I will eventually remember to get the cable thingy I need to connect the camera to the computer(s) - or I'll save up and call the geek. Syb

I love blue and yellow, I am trying it too.
One thing you might try with photos, if you have a smartphone and take photos, you can log into DG on the phone, and upload the photos, up to 5 at a time, it is quite easy. This skips the computer entirely.

Oh, Pistil, wouldn't I love to. Any kind of cell phone and I me? is a failed combination. Never can find the darn things. Now that my laptop and camera and printer all know each other I just need the six collar cable. That maybe is a copeable option. Syb