Cold plays a subordinate role in getting a plant to go dormant. Simply making it cold will mostly just kill off foliage. The dormancy process begins at the summer solstice when the days are longest. The shortening days (two minutes a day after the solstice) reduce the daylight exposure for trees. That shortening daylength triggers hormones in the tree that tell it to begin the process of converting from active spring growth to preparing itself for dormancy. At this point, it's not anything to worry about. It's still summer. You have a month or more of it. Let the tree alone. Hope you have a place for it to overwinter. 6b is a little on the cold side for sequoiaI live in zone 6b will it get cold enough to go dormant
There's a 150 year old giant sequoia in Michigan. But it's a real oddball.Length of winter is as or more important than depth of cold. The ground is affected differently than the air and slowly changes temperature. Giant Sequoia (Sequoiadendron giganteum) is a zone 5 tree in the far west, but falls into the category of "not certainly hardy" in mid-western zone 5 where the occasional Alberta Clipper will linger for a couple weeks and kill the roots. This is not a new tree. There are almost none that have survived in the east because our winters are longer and colder, -look around. Protect the roots from freezing and you're golden.
You can get a "competition tree" with the species. This one has been around quite a while:
About Craig Coussins' relations with the Giant Sequoia: The Giant Sequoia. When I was ill with Cancer back in 2000 I made the pilgrimage to Sequoia National Park in California. My wife asked me whatwww.bonsaiempire.com
I said it is possible IF you can properly overwinter it. I'd bet most people aren't going to take the time. Marginal species like this require attention in the winter that can tire you out. I have a live oak collected in Texas here in Va. Have had it for over 25 years now. The species is marginallly hardy here IN THE GROUND. It was in decline after a few winters in mulch in my backyard. Didn't die outright, but was losing steam. I have taken it to a cold greenhouse for winter storage for 20 years now without fail. It has prospered with that treatment. It has taken commitment and caash (not to mention elbow grease since I have to heft the 120 lb tree to the street and get it loaded into a special purpose built box in the back of the pickup)The trip to the nursery is two hours one way on I-95 (busiest most congested Interstate in the U.S.) and costs not an insubstantial amount of money to store there. You are at the beginning of your journey with these trees, so before you start telling me I'm wrong, let's see if you still have them 25 years from now. BTW that die back is telling you something about the future...I'm not trying to dispute you @rockm...just stating my experience.
Here was that same tree coming out of winter. Most of this occurred after our deep cold spell.
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One side of the tree died back pretty hard.
Here it is after some cleanup...I left a lot of dead foliage because there was some live budding in there.
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This year has been my worst for die back on these by far...but this kind of die back has occurred after every winter.
Now, you can say this was all my fault and I don't know how to care for a tree. That may be a fair statement, actually But I am not inexperienced despite my fake internet point tally and short membership on this forum. While it is possible to keep these trees alive in 6b in a pot...they are, shall we say, on the high maintenance side in this zone...at least compared to my dawn redwoods which I've done just about everything one can do to kill a tree and they trooper right on through!