Though we are nearly opposite sides of the country, your rainfall amounts and summer/winter temps sound like mine (Tennessee). We have clay soil here. I have had good luck with Ph. Rubromarginata and Ph. Henon - grow fast and thick. About 20 ft high right now (we've had a couple of drought years or I imagine they'd be a bit bigger). The rubro can take the freak ice storms and cold winter winds too.

Where exactly are you? I grow about 60 different species of bamboo in the Greater Seattle area (Zone 8).

Hi Kudzu.., I am in Mukilteo about 3 blocks from Puget Sound. Western Garden says it is zone 5, other sources via zip code say 7 or 8.

Elzbetta, how long has your bamboo been growing to reach 20 feet?

I'd like to hear more. Thanks, Jerez

Most of my bamboos are 5 yrs old but the rubro and the henon sent out tall shoots the 3rd year. Considering they started as skinny little 3 ft plantings, I was impressed. There'd be a 10 footer, or higher, shooting up here & there. It wasn't till the 4th year that they started to 'fill in' and start looking more like a mini grove. We don't get a lot of rain and I haven't been fertilizing much. I do put down a lot of pine needle mulch every fall. Our fields are not ideal conditions for most plants but the bamboos seem quite happy to grow in poor conditions.

FYI
Sunset uses their own zones so Sunset 5 doesn't mean USDA 5.