How much of a Canadian Hemlock branch can you prune and still get growth on that branch??
Canadian hemlocks are tolerant of shearing to maintain a size. Don't remove more than 25% of the branch, or of the entire foliage in a one year period, is the rule of thumb for best management practices in pruning.
https://www.gardeningknowhow.com/ornamental/trees/hemlock/canadian-hemlock-care.htm
I have a beautiful very large Hemlock tree in my garden and this year the needles have been turning yellow. I don't see any insects on it and I hate to cut it down. Is this something you can help me with?? Thank you in advance.
Your zone is 5b. This article discusses one of the typical problems for hemlocks. https://www.gardeningknowhow.com/ornamental/trees/hemlock/growing-hemlock-trees.htm
Another suggestion is to contact your local agricultural extension agent to discuss the possible problems with this tree: Here's a link for your nearest extension service:
https://www.gardeningknowhow.com/extension-search?zip=19720&radius=50&services_search_action=search&submit=Search
The top portion of my Hemlock was broken off at the main trunk, about 3-4 feet above the ground. If I trim and clean up the break will the tree continue to grow? will it regain it's shape?
Yes, it can tolerate shearing.
This article should help:
https://www.uaex.edu/yard-garden/resource-library/plant-week/hemlock-canadian-1-18-08.aspx
Is there a big diff in early Sept vs spring timing? How do I 'measure' how wide the root spread that I must dig in order to move the tree successfully? I have read different ways to estimate that.
This will be best measured by the tree's caliper. Here is an article that will help:
https://www.gardeningknowhow.com/ornamental/trees/tgen/transplanting-trees.htm
It won't really matter when you transplant, just that it is mild when you do. There are some pretty specific things to know about the location that it needs to be settled in, though. Here is an article that will help:
https://www.gardeningknowhow.com/ornamental/trees/hemlock/growing-hemlock-trees.htm
My childhood home has a hemlock that maybe 100 years old. We are selling the house and have found three baby hemlocks in our gardens that we would like to take to my current home. The tallest is about 6 or 7 inches high. We would like to move them before the house sells and the ground is frozen. How do we move them? I’m wondering if they should all be in the same pot and placed outside until spring. Or should we put them in the ground and mark where they are to keep them safe. What do you suggest?
As long as you transplant them to a shade area, they will not be too picky. They will survive temperatures much colder than you will see in your area, so transplanting them now will not be a problem, as long as the ground is not frozen.
They are very hardy and will survive just about anything, as long as you keep them out of the sun when they are young.
Here are some articles that will help:
https://www.gardeningknowhow.com/ornamental/trees/hemlock/growing-hemlock-trees.htm
https://www.gardeningknowhow.com/ornamental/trees/tgen/transplanting-trees.htm
The site is 4100 feet elevation. Gets very strong winds at times any time of year because we are on west facing side of Roan Mountain and can see forever. Trees would be near the north boundary of a National Forest but can be planted in an open area.
They would need to be planted in a protected area rather than in the open because they don't handle strong winds well. The soil also should be acidic and they need regular moisture in the early years. Here is more:
https://www.gardeningknowhow.com/ornamental/trees/hemlock/canadian-hemlock-care.htm
https://www.gardeningknowhow.com/ornamental/trees/hemlock/growing-hemlock-trees.htm
What is this growing in my garden bed?
That is Ragweed!
https://www.gardeningknowhow.com/plant-problems/weeds/ragweed-control.htm
https://www.gardeningknowhow.com/lawn-care/lgen/lawn-weed-identification.htm