I can answer the first question... yes you will still be dealing with the Euphorbia! Even a 2" piece of rhizome will come back. But we can hope that it is easier to deal with next time it comes up. I don't know how Choisya will respond to hard pruning, but I am impressed 'Sundance' survived the winter for you given your temps in February. Given it looks awful, personally my choice would be cut it back hard and if it dies or fails to grow well, then replace it.

Hi Ian
Thanks for the reply. I was afraid of that (in regards to the Euphorbia)..... Oh well, I have dealt with worse and will just keep weeding! The Sundance was/is in a protected spot and was sort of mulched with Euphorbia and had a huge Rhodie overhead. I will cut it back as an experiment and see what happens. Thanks again!

Give that euphorb an inch and it'll take a mile!! :-)) But a very handy plant for certain, very restricted growing conditions - like underneath a deck.

And yes, the choisya will take hard pruning well. I whack mine back several times a year as their growth is very robust and vigorous. And they never blinked during the February freeze :-)

When it was mentioned there were 2 thermometers on the site the one giving the 18F reading (rather than 8F) corresponded better to what others in the region noted. 18F specifically was reported repeatedly, as though there was a widespread pattern. Down on the flats north of town, where due to lack of air drainage it would be about as cold as it gets there Antique Rose Farm got a 14F reading. Snohomish is in USDA 8. Zone 7 is the western slope of the Cascades.

I've had the tops of the euphorbia freeze back here, when a genuine cold winter came along. A site that did not have that damaged might not have gottern cold enough for choisya to be affected either. A winter that has a few things damaged here and there is not a cold winter, when we get one of those losses are much greater.