What are the proper methods for trimming and pruning a Leyland Cypress tree?

I will check with my husband and get back to you. He’s a certified tree expert.
It may be a while, he’s making me breakfast at the moment! :)

Yay!

I use to grow these at the tree farm and we would have dozens of rows of trees and they could all look different depending on how they were grown and what their mother plant looked like. I wouldn’t do any major pruning at this time of the year. We cloned the ones that were really good trees to ensure they would be replicas. When it comes time to prune just shape it how you want but it may just not be a good tree. I am not a tree expert but I am going to school for horticulture and have grown hundreds of these trees.

So how close can I plant this tree?

Close to your house? We had them about three feet in front of our house in the front flower bed.

Or how far apart to plant them? A good nursery, (perhaps where you buy the trees) can advise you. If you do not prune properly, they will spread sideways like a woman in a hoop skirt.

And most people plant trees too close, because initially they look lonely. A mature cedar can be pretty bushy. I see that they grow only in zones 6–10.

Yes, how close together can I plant them, so that they appear as they do in the first photo?

I planted one line of 25 trees 10 feet apart and they are filling in nicely. I have another established row of about 12 trees that are 12 feet apart and w/o trimming towards the bottom the branches are quite thick and dense. They keep growing up to about 50 or so feet and them stop. I just went out and measured the width of the established row. The limbs extend out about 20 feet out at the base from one side to another, so each limb extends out 8 to 10 feet. SO be sure not to plant them too close to a structure.

I finally have some answers for you S. If you want Leyland Cypresses, he says you should cut off all but one leader (point) off the top if more than one develops, then just prune the outer branches towards the center to keep the center full. However, he recommends you go with ‘Green Giant Arborvitea’ instead. It is a nicer looking plant, and holds up better in the long run. He suggests you buy 3 gallon plants, and says they’ll grow about 3 feet per year. Plant them 6 to 8 feet apart, and trim as above.