I would like to purchase an evergreen in a container and keep it outdoors until the Christmas season. Then place it in Church for the holidays--return it outdoors for the rest of the year. Am I asking too much of a plant?
This is asking a lot of the plant. Staying outdoors until Christmas is fine and bringing it indoors is fine, but it is the placing it back outdoors that is the problem. What happens when you bring it indoors is that it causes the plant to come out of dormancy. Many things happen in dormancy that protect the tree from the cold and when it comes out of dormancy, it loses that protection. Trees can make it if placed back outside, but their chances of dying increase significantly, especially if where you live gets very cold in the winter.
I planted evergreens 15+ yrs ago and half are orange and dying rapidly. What can I do?
It is hard to say, but if they have been healthy up until now, then you should check for environmental changes that could be making them sick. It may likely be plant rust too. This article will help with that:
https://www.gardeningknowhow.com/plant-problems/disease/learn-about-plant-rust-disease-and-rust-treatment.htm
In the corner of my yard, I have a bushy hedge that grows from the top of my retaining wall with branches that cascade down the wall to cover it. Recently I noticed that a few of the branches were turning brown. So as I went to snip them off and spray the hedge, I picked the long branches up and underneath was MAJOR discoloration. The underneath root area is pretty much completely blackened and brown, and a white dusty powder was blown up. My question is: Do I need to completely get rid of the hedge? I love it and want to save it if I can.
Yes, I would trim it all back and then treat it with a fungicide. The white powdery stuff is powdery mildew. Here is more information that will help with treating it: https://www.gardeningknowhow.com/plant-problems/disease/get-the-cure-for-powdery-mildew.htm
https://www.gardeningknowhow.com/plant-problems/pests/pesticides/neem-oil-uses.htm
Are there any evergreens that tolerate wet soil?
False cypress, dwarf loblolly, thuja and balsam fir will tolerate wet conditions fairly well.
I am looking for evergreen shrubs to grow in two half barrels that frame my garage door.
Boxwoods are popular for this. They grow slowly so do not need to be repotted often. You also might try looking at Inkberry. It has a similar look to boxwood. It grows slowly as well, but is typically a little more cold hardy than boxwood and can take the winter better.
This article will help with the appropriate soil mix for your container evergreens: https://www.gardeningknowhow.com/special/containers/proper-soil-mix-for-evergreen-container-plants-and-trees.htm
Can I plant my potted 5 ft. evergreen tree in Sept/Oct in New England? I have had an indoor 'Christmas' tree for a couple of years now. It has gone from being a sapling to a nearly five foot tall tree. We have purchased a home and I would like to give it a permanent residence in the yard. I have kept it in a very large planter, always kept it moist and fertilized (tree food stake). It looks very healthy and has thrived. It has spent the spring and summer months outside and is still outside currently; however, I worry in the upcoming months whether I should plant it now - or bring it in till spring. Any advice?
Most Christmas trees are normally grown in cooler climates. Since it is not accustomed to being outdoors, I would leave it over winter as is and slowly acclimate the tree outdoors in spring, planting it as you would any other tree. The tree should go into dormancy and can be fertilized following its plantation outdoors. Here is an article that you may find helpful: https://www.gardeningknowhow.com/ornamental/trees/christmas-trees/plant-your-christmas-tree.htm
I have several large evergreens that have been in the ground for 2 to 3 years. The top half of the tree on 5 or 6 of them are noticeably "crooked" or leaning one way or the other. Would it be harmful to the trees to gently attach them and pull them to stand up straight??
When pulling a limb or trunk to (un)bend, make sure the items you use will not "girdle" the bark. I always suggest that people use a legnth of "dead garden hose" with a sturdy rope or wire run through it. The hose will keep the rope or wire from girdling (which will kill) the plant. Use a metal T-post from a farm or tractor supply store to attach the rope or wire. Use a 6' or 8' post, the 5' will not be sturdy enough.