Hey there Parker Turtle,
Interesting stuff! I too live in Seattle and have a cold hardy citrus collection of my own. In the ground i have:
Indio Mandarinquat
Owari Satsuma
Kuno Wase Satsuma
Nagami Kumquat
Fukushu Kumquat
Marumi Kumquat
Calamondin
Chinotto Sour Orange
Bloomsweet Grapefruit (kinkoji)
Yuzu
& Poncirus trifoliata
To date, these have all seen 18 degrees unprotected with no damage across the last 3 winters.
If you're ever looking for rootstock, I've got a couple hundred poncirus trifoliata that are just about grafting size! And I'm always on the lookout for new varieties.
