I suppose it depends on when you planted them, how well they were established, and how sturdy the branches are. You might want to leave them tied at this late date. They're not going to have enough energy to learn how to stand on their own this time of year, I wouldn't think. They tend to get a bit of frostbite anyway especially if they are out in the open in an unsheltered spot. I have a well established one against a fence that is about 6'x6' that does quite well with no protection short of a tiny bit of damage at the branch tips.

The stems do tend to be rather lax. The large shrub in my old garden was routinely smashed down by snow loads but recovered nicely once the snow melted or was removed. I'd remove any staking as soon as the worst of the winter weather is over. Nurseries tend to stake these types of plants more for aesthetic/tidiness reasons than for actual support purposes.

Frost protection is unnecessary but as noted above, severely cold weather - like what we experienced a couple of weeks ago - can damage the foliage. However, these shrubs take a lot of pruning very easily and any damaged portions can be easily removed without worry. For newly planted shrubs (within the last growing season), I'd consider covering with a protective cloth like Remay or harvest cloth should another Arctic front be predicted.

Hot climate shrub with characteristic vivid yellowish-green foliage color shared by some hebes, ceanothus, evergreen magnolia etc. These all like a hot sunny wall or other spot that heats up markedly in summer and does not get the full blast during Arctic periods. Even the locally native evergreen ceanothus is for instance in Bellevue and vicinity almost entirely limited to hot places such as sunny margins of paved areas - and had a big die-out there in the 30-year cold of the 1990 winter.

Big specimens are again present on some sites there but not to the same extent.

Ron, I have seen Choisya in dense shade near Northgate, and right after the 1990 freeze they looked fantastic. Very healthy green.

When I lived in California, Choisya looked exactly the same as most specimens do here.

Thanks everyone for all your helpful suggestions. Very helpful.

Shade during a hard winter protects broad-leaved evergreens (and other plants) from being damaged by the sun during low temperatures, without snow cover.

In marginal areas such as the high mountains the vegetation is lusher and more diverse on cold, shaded slopes that collect snow.

A Mexican orange in the shade may not die back as readily as one in full sun during a hard winter, but it will also not be as full and floriferous the rest of the time. And if it gets cold enough, they will all freeze off regardless of exposure.

So what's "cold enough"? Last winter's single digits? Mine (one of each of the three common varieties) were not bothered.

both last winter and this winter the mexican orange has been a great performer here in portland. no signs of stress on any i have observed.

>So what's "cold enough"?First sentence of description in commonly used Sunset Western Garden Book is

Mexican native hardy to 15F/-9C

According to Public Information Statement documents put on the internet by the National Weather Service Sea-Tac went down to 14F last year and 16F this year. The well-established Sundance up the street from me (southwest Shohomish County, less than a mile from Puget Sound) is now all brown on top, where the pure yellow color was.

Everything has a minimum temperature below which it will be damaged - after only a few hours or less of exposure. Exactly how cold it gets on each specific planting site will determine how a planting comes through. The state of maturity of each specimen at the time of the cold determines how it fares, immature growth does not have the full level of hardiness for the species. Hot climate plants often have trouble ripening their growth in time for our December cold snaps - unless situated in an extra hot spot on well-drained soil that warms up nicely in summer.

perhaps that is why the mexican orange seems to do better in portland? hotter summers...

it hit about 12 degrees in my hood and i haven't seen any brown on any of a number of mexican orange shrubs.

Boy, your head must've felt pretty cold then.