Transplanted Vanderwolf Pines

Q: How cold hardy are Vanderwolf Pines? I’ve read the trees are suitable for zone 4 and above, but I question that. I purchased a small tree in the spring of 2008 and it grew well until the winter when I noted that most of the needles turned brown and dropped off in the summer. Fortunately, it rebounded with new growth and wintered well in 2009-10. However, since our cold snap last November (I live in Coquitlam, B.C.), I’ve noted that most of the needles on the new growth are turning brown!

Is it worth keeping if it cannot withstand temperatures below -10C?

“Vanderwolf Timber Pine” (Pinus flexilis ‘Vanderwolf’) should be winter hardy to our climate here, rated zone 6 (USDA). I believe the pine may be suffering from transplant shock and natural fall-needle shedding. I’m assuming that the pine is correctly planted and is probably from a “Ball & Burlap” (B&B). B&B plants normally experience transplant shock during the first and second seasons when some brown needles will be noticed. Just brush away the brown needles. Apply an organic mulch at least 5 to 10 cm thick (2 to 4 in.), ensuring it doesn’t encroach the main stem. Ensure deep, but infrequent, watering during prolonged dry spells. You may want to try a transplant solution to promote rooting (follow directions on the label). I suggest using fertilizer regularly after one growing season.