Maybe I'm late to this party, but I only found this out recently. I was browsing my options in the frozen section last week and saw something unusual. Was that hashgacha? On Gardein? Yup.
According to their website: All gardein frozen retail products made after July 1, 2013 are certified kosher (by BC Kosher – a division of the Orthodox Rabbinical Council of BC Canada) with the exception of our chick’n sliders, beefless sliders, breakfast sandwiches, and Holiday Turk’y Roast.
I took some 7-grain crispy tenders home and they were delicious. The outside got properly crispy and had flavor of its own. The protein was firm and even did well on a plata for shabbat lunch. We'll be trying out their mandarin chick'n tomorrow night for dinner.
Since it sometimes takes companies a while to get through old packaging without the hashgacha, I wrote to them to find out the relationship between production dates and the "best by" dates stamped onto the bottom crimp of each bag. In my local whole foods, only two products have the new packaging but why limit myself if I don't have to? I'll report when I hear back.
Edited to add that it looks like all of the products are not only kosher but also pareve.