Even planted in the ground, ceanothus can be a bit iffy in a tough winter. It seems to thrive best in the PNW when sited close to the Sound, benefiting from the moderating marine temps, but I've even seen beachside plantings exhibit winter damage. However, for $4, I say plant and enjoy for as long as you can........heck, I'd spend that much on annuals for a container planting!!

Thank you. I'll plant it and hope for the best. We moved houses last year, within the same county, and I've been surprised at how different this garden is than my last garden in the city. The Sunset zoning system captures the difference, whereas the USDA system has both gardens in the same zone.

Actually in western WA east of the Sound the Sunset and USDA zones happen to line up pretty closely. As I remember it it's something like 8 a = 4 and 8 b = 5.

The particular ceanothus you are asking about probably isn't going to be very hardy there (like many of them it's good to about 15 degrees F., in the ground) but might in fact last long enough to produce a plant of some size before being spoiled by cold. Also your planter may not be big enough to house a fully developed example anyway.