just find the annual growth rate of both parents.. and interpolate from there ... if both are over a couple feet per year.. i think you have your answer... because being trees ... they really arent going to slow down.. in your life time .... frankly.. their potential is a forest tree ... the problem with what you read.. is the inference of common names .... which always leads to mis-interpretation ... but in this case.. it made you think a bit deeper into the potential.. so it did serve a purpose .... ken

It comes from parts of the PNW that are dry in summer - Sequim Washington has only 14" of rain a year in winter too, but is of course much cooler than you year-round. So it's not particularly remarkable that they soldier on for you. In Barcelona, Spain, for example, which is summer dry though not quite so much as California, there are huge unwatered hedges of the Asian summon-monsoon loving Pittosporum tobira. Now that's a surprise. Someone from California will know for sure but I think after 3 years of stingy watering it should be able to fend for itself. You don't want to indulge it. Just water it enough in summer to keep it from dying. This post was edited by davidrt28 on Wed, Jan 23, 13 at 17:31

I know this is an old thread, but I'd thought I'd share the following. In Appleton, WI, my friend has this on a standard...at least 5-6 years now. It's always done great, does not even get winter burn. Also, farther north in Luxemburg, WI, there's a family owned nursery called "The Plantscapers". They have one that's about a 12' tall tree...no winterburn, doing great. Luxemburg is close to Green Bay, and much closer to Lake Michigan than Appleton, but still considered 4a/5b. The winter of 2014 was particularly hard on evergreens throughout the Midwest, yet both the plants at these two locations pulled through with flying colors, in unprotected locations.

I planted a bunch of different kinds of western red cedars (some nobody knows what exactly they are) and one incense cedar. The incense cedar is a lighter brighter green and more fluffy and feathery. It's really cute! The incense cedar is supposed to be slower grower but mine is growing faster than the western red cedars did at first. The incense cedar just immediately took off with no transplant shock. It's breathtakingingly beautiful. Several of my western red cedars were in sad shape when planted; some's leaders had been cut off from drought death. But they've all come roaring back sarting this spring (planted December 2005) and especially since late August have been exhiting a tremendous growth spurt. Both the western red cedars and the incense cedars are exceedingly lovely trees.