I have a 1 year old Magnolia growing in a large pot, can I plant this in garden, if so how and when should I do this?
Yes, you can transplant it to the garden. These articles should help:
https://www.gardeningknowhow.com/ornamental/trees/magnolia/magnolia-tree-care.htm
https://www.gardeningknowhow.com/ornamental/trees/tgen/how-and-when-to-plant-trees.htm
in the bottom 2 feet. Any clues . Can I prune the small one to just above the leaves
I see signs of soils that remain too wet, or heavy. This is likely the root of the problems.
The issue that you run into, here, is that many species of Magnolia are grafted. The bottom growth that you see is likely not that of the Magnolia that you intended to purchase. I would not keep this growth, but you have no choice if the top is dead. Make sure before you cut the top of by using the scratch test:
https://www.gardeningknowhow.com/ornamental/trees/tgen/tree-scratch-test.htm
If the top is still alive and you see signs of budding, then I would remove all bottom growth. It the top is dead, then cut it off and let the bottom growth take over, as a different Magnolia species. Repot into fresh potting soil and compost mixed into a container which has drainage holes to allow all extra water out.
As for the one with top growth...
Leave it alone, with the exception of giving it fresh soil as described above, and potting into a container with drainage holes to allow all extra water to leave.
Treating with a fungicide will help, as well:
https://www.gardeningknowhow.com/garden-how-to/info/using-fungicides-in-garden.htm
https://www.gardeningknowhow.com/special/containers/how-to-grow-container-trees.htm
The tallest one lost absolutely all of it’s leaves, the branches all look brown. The other retained most of its leaves and has green branches. It has been a month and nothing has happened. Is my tree dead?
You can give it a scratch test to see if it is still alive. Here are the instructions below. I see it was topped at some point and there are a bunch of water sprouts. I may also see some insect borer holes. Sometimes a tree will drop its leaves due to environmental stress, but I would think new leaves would have grown back by now.
These articles may help you pinpoint the problem. You can also contact your local extension agent. I've included a form to locate the office.
https://www.gardeningknowhow.com/ornamental/trees/tgen/tree-scratch-test.htm
https://www.gardeningknowhow.com/ornamental/trees/magnolia/magnolia-tree-diseases.htm
https://www.gardeningknowhow.com/plant-problems/disease/verticillium-wilt-treatment.htm
https://www.gardeningknowhow.com/ornamental/trees/tgen/tree-borer-insects.htm
in our development white magnolia tree grows.
These are hardy in USDA zones 10-11 so I wonder if they are the same as the ones growing in your development. There are other magnolia trees with white flowers that are hardy in your zone 7 such as Southern Magnolia and Star Magnolia.
https://www.gardeningknowhow.com/ornamental/trees/magnolia/magnolia-tree-varieties.htm
Is it ok to move a young tree just getting established without risking damaging it
Unfortunately, there is great risk of damaging the tree, since it is just barely getting established. If you must move it, I would do so in winter, during dormancy.
https://www.gardeningknowhow.com/ornamental/trees/magnolia/magnolia-transplant.htm
https://www.gardeningknowhow.com/ornamental/trees/tgen/moving-mature-trees.htm
Please Help. I purchase Magnolia Tree in June when bought the tree the leaves where green; but after I had it planted by professional landscaper. He advised me to water the every day morning and evening for about 20 minutes. Also I had applied some fertilizer around the base of the touch of tree; now in the last 3 weeks the leaves have fallen and turn yellow- brown. I stop watering the tree after I saw so many leaves fallen off the tree. I do not know what else to do; also I had Palm tree that had die due to the winter storm here in Texas ( February) I replace it with the Magnolia tree. Please help.
It may have suffered from fertilizer burn. Usually new trees don't need fertilizer the first year. Also, it needs regular watering, but take care not to oversaturate the soil or leave it too dry either. Here is more about magnolia trees.
http://www.missouribotanicalgarden.org/PlantFinder/PlantFinderDetails.aspx?taxonid=249453&=
https://www.gardeningknowhow.com/ornamental/trees/magnolia/southern-magnolia-trees.htm
I planted seeds in March after 4 months of stratification and they are 5 or so inches high. Winter will be coming soon and I can't find any information on how to keep them safe during the cold months. I'm in Canada so our winter can be quite cold. Any help is very much appreciated.
Are your seedlings in the ground? If so, they need to be covered for the winter. You can completely cover them with 6 to 8 inches (15-20 cm) of mulch. Then remove the mulch in spring. If your seedlings are not planted yet, keep them inside for the winter in a cool room next to a window. Here are more ideas:
https://www.gardeningknowhow.com/plant-problems/environmental/protecting-plants-winter.htm