@Barkslip any input? I know you know your evergreens as good as anyone.
My input would be a thuja green giant, fast growing and tall.
Rhododendron can also grow to the minimum height you are interested in and stay there, although they may take more time than other options.
You could also intersperse shorter evergreens amongst deciduous trees, or even grow deciduous trees and include evergreen vines in the planting like Oregon Grapes.
I’m not sure if they get tall enough, but strawberry bushes might be an option? I discuss the previous two in my Bring me a Shrubbery thread.
Maybe somebody like @Stan has better ideas than myself being he’s in California.
Deodara Cedar is a great choice. I’m sure there’s faster, however. It does exactly what the poster wants becoming globular in shape as it ages. Same with Araucaria auaucana (Monkey Puzzle) but it’s more open so they’d see thru. Still a cool tree. I’d bet Cupressus cashmeriana is super common there but I’d have one if I lived in the south or California. It’s zone 9. It’s the wrong shape however. It’s a weeper that doesn’t become globular.
I just don’t know the zone 9 pines to comment. Spruces there are many. Then there’s all the exotic’s I don’t know very well or completely forgot about.
Italian cypresses planted two-three feet apart make a great green wall. Thuja is also a good option.
If fruiting trees are preferred, then you can go with citrus, Owari Satsuma mandarin can be hardy enough for you, depending on how cold it gets in your location. Make sure it’s not on a dwarfing rootstock.
Green Giant thuja is magnificent. I have 14-year old 30 foot trees spaced 3-meters now touching. It’s wide at the base and narrow as it goes up. Do not space this cultivar 2 meters like a lot of people do. Go at least 4-meters or better for anyone considering this as a screening tree or single-specimen. It’s really not the correct application for this situation. I needed to comment about it. Stan suggesting something else that’s tall and narrow is the correct application… also the correct plant for dry and arid soils/climates. Another cultivar of Thuja, ‘Hetz Wintergreen’ aka ‘Wintergreen’ is also a great candidate to Italian Cypress as is a Juniper: Juniperus virginiana ‘Taylor’. I have photos of all three from plants here at my home if you simply ask. All 14-years old.
Lets see, zone 8 or 9a? Are you around Brisbane or where? In QLD?
If so, you could plant Satsuma or Mandarin as many of those types can take 20F or so, some types such as Owari Satsuma or Miho Satsuma as low as 15F or so and should be fine for moderate frosts, and are evergreen and also make great fruit. And are beautiful.
I didn’t know it gets as cold as zone 8 in Australia.
From fruit trees:
Citrus: Satsumas, kumquats
Some of the myrtle family fruits (there are some that grow that big)
Loquats
Cornus capitata
Some of the Mexican cold hardy avocados?
Oh ok. Yeah Canberra would probably bee too cold for mandarins long term. Depending on your micro climate. I know people with Satsuma in Louisiana zone 8b that have taken in the 12 to 14F range it gets below 17F about once per decade there down in the 12 to 14 range and the bigger trees survive. Some with damage and some hardly any. But below 15F is rosky unless you throw a tarp over them. Leeland cypress might be a nice evergreen option. For citrus Prague Citsuma (5F) and Ten Degree Tangerine (8F) should be nice options that will work for you since they can take more, but they probably are not in Australia yet.
Cedrus Deodora grows wonderfully in Charlotte, NC, Columbia SC and they have summer heat index 105 or more in daytime and night time heat index in the 80’s sometimes. I am not sure how it gets along in South Florida.
I planted one in 2009 and one in 2015 here in Kentucky z.6 that are alive and thriving…though the central leader burned up at -19F one year on the older tree.
Cryptomeria radicans (Japanese cedar) makes fast growing screens here in the Southeast US and seems to have less disease issues than Leyland Cypress. The wild type might be too big for your purposes (50-70ft), but there many cultivars of varying sizes from bush size on up.
Cryptomeria is a good suggestion, if available. My 20-year old is ~25 feet tall, has gone through +15F to 110F. Cold temperatures enhance winter bronzing. Does not like to be crowded.
Do yall have our US native Mississippi southern Magnolia? Very beautiful small tree with big green leaves it should stay evergreen for you as it does in northern Mississippi.
Here is a decent picture of the Mississippi Southern Magnolia, they are common in Mississippi where it gets 5F even colder. And are a smaller tree. In your drier mountain location they will probably stay smaller than in the humid lowlands of Mississippi but even there they are usually around a 20 to 30 ft tall bush tree sort of lile this pic:
