There are several trees that loosely get called sequoias: Sequoia sempervirens (coast redwood, z 7-9), Sequoiadendron giganteum (giant redwood, z 6-8), and Metasequoia glyptostroboides (dawn redwood, z 4-8).

Do you know which you have? Can you post a photo?

I can't imagine that you have a coast redwood, especially considering that the really cold temperatures winter before last would have caused severe damage if not outright killing them. The other two are quite possible, with Metasequoia/dawn redwood being most likely since it's fully hardy and wouldn't have been bothered by winter temperatures well below normal for zone 6. I know that other folks in zone 6 in MA and RI commented on borderline hardy plants being damaged over the last couple of winters by more severe cold or sudden temperature shifts. If yours don't show any damage, I'd suspect that they are dawn redwoods.

When I lived in Amherst, MA, we had an immense (well, by east coast standards, anyway) dawn redwood (I believe) in our yard. It was at least 60 ft tall, probably almost 4' diameter, and had clearly been there for a very long time. It was deciduous. And beautiful.

I grew Sequoiadendron in Rhode Island z6b for many years until I moved to Massachusetts. They are quite easy in my opinion. There are many located in the town of Bristol, RI.

Sequoiadendrons in Rhode Island

https://www.giant-sequoia.com/gallery/usa/rhode-island/

In Massachusetts

https://www.giant-sequoia.com/gallery/usa/massachusetts/

How about Montana

https://www.giant-sequoia.com/gallery/usa/montana/

Smithfield,RI

http://www.monumentaltrees.com/en/usa/rhodeisland/providencecounty/6907_greenvillelibrary/

I planted one in my zone 5 location in Central Massachusetts and the young tree did not survive the winter.

Boston College has a single metasequoia which is the same height as the surrounding canopy. This species is the smallest growing species according to the web, yet still tops out around 200'. The climate and soil must prevent it from becoming something truly spectacular.

Just met a potential client growing Metasequoia in Canton.

That must have been a great surprise! Here's a Metasequoia near my house, decent size.

Here's a Sequoiadendron gigantium you can see while driving by Blitheold Gardens in Bristol, RI. They have loads of SGs including the largest specimen in New England

Here's a couple SG at Roger Williams University, Bristol, RI you can see while driving by.

Another SG planted across the street from RWU. SG are planted everywhere in Bristol!

Another massive SG in Bristol.

Another SG in Bristol

Another SG.............Bristol is the SG capital on the east coast.

Off topic, but here's the largest southern magnolia I have ever seen............massive.

The only species of Sequoia-related tree I grow in NJ/Zone 7 is Metasequoia..., which deals quite well with our winters and summers and there are massive species of some age about the state. Climate is much too extreme for a Coastal Red. Even Metasequoia is not without its hardiness concerns. The problem is our crazy North American climate. This is an Asian species adapted to a temperate, Asian climate that is not as screwy as our own climate. East Coast Winters and Springs can be very variable..., subarctic cold to subtropical heat. All Sequoias seem to prefer a climates that that are somewhat maritime and protected from extremes. Cold is not the only enemy...., so is heat! Several years ago, I had a GoldRush Sequoia leaf out only to char in mid 90's heat and wind in early-mid April. So too, if the tree leaves out too early in the Spring it can be hit by late frosts.

P.S,, Southern Magnolias..., one of my favorite trees.

Tim, thanks for the photos! Way to do this topic justice.

Sub- Maybe siting of Sequoia trees in protected coastal areas could help them adapt?

Although we might have lost the OP, this is a really interesting thread! Thanks to folks for sharing their experience.

I'm sure these trees like the coast better since the climate is moderated. I know a couple SGs further away from the coast..............this one is located in Smithfield RI at the library. You can see the top of the SG from the road.

There is also a SG at Ponaganset Middle School located off Anan Wade Rd, Glocester RI. No street view.

There’s one in Boston and a couple in Manistee MI, I’m in NE Ohio growing one right now, they are extremely easy to grow in zone 6, as long as you know what you’re doing