The Camellia Society of the Potomac Valley, which includes Maryland, lists the following camellias in their website. The list is not limited by height though but it is extensive. Japonicas that bloom late would be my recommendation as most will be taller than 8'.

http://www.cspv.org/wp-content/pdfs/CamelliaVarietiesPotomacValley.pdf

Do not forget about early flowering sasanquas as they too make nice hedges:

http://www.cspv.org/wp-content/pdfs/CamelliaSasanquaPresentation.pdf

https://camelliashop.com/blogs/ornamental-camellias/sasanqua-camellias

You can also consider attending meeting to meet and discuss with society members! Meetings are held the second Sunday in October, November, December, February, and March. There is a mini camellia show in the Nov meeting. Camellias are sold in March-April.

http://cspv.org/about-cspv/

Luis

Thanks so much!

"... at least eight feet tall? "

That would be just about any of them. LOL!

Camellias come in different flower forms and shades of white, pink, red, variegated. So you might look them up and see what you prefer. For zone 7a, you'll want a hardier variety.

Consider the April series, since they are easy to remember..... 'April Dawn, April Tryst, April Kiss, April Remembered, April Rose, April Snow, etc.'

Any of the Ackerman 'Spring' or 'Winter' series such as 'Spring's Promise', 'Spring Cardinal' or 'Winter's Fire'.

Any Longwood Gardens introductions such as 'Longwood Valentine.'

Any super hardy camellias from Korean regions such as 'Korean Fire', Korean Snow.

A good list of tried-and-true japonicas for zone 7a should then include (besides the April series): 'Lady Clare', RL Wheeler, Paulette Goddard, Adolphe Audusson, Gov. Mouton, Jerry Hill, Blood of China, Red Aurora, Prof. Charles Sargent, Lady Vansittart, Mathotiana, Korean Fire, Red Jade, Pink Icicle (Spring), Winter's Fire, Red Fellow, Springs Promise, Betty Sette, Korean Snow, Aida, Longwood Valentine, Longwood Centennial, Hokkaido Red, Spring Cardinal, Kumasaka, Berenice Boddy, Anacostia, Variety Z, Arctic Rose, Bloomfield, etc.

Species C. chekiangoleosa is especially beautiful and hardy.

Thank you so much!

I'm in the Shenandoah Valley in Virginia so a bit colder than your area (zone 6B). I've had good success with some, and then failures with others that surprise me.

My camellias that have done well are

April Dawn, Spring's Promise, April Snow, and April Remembered

Plus a number of unknowns that I have rooted from my mother-in-law's plants in NC

Korean Fire is growing very slowly (13" tall in 5 years!)

and I have one surviving C. Chekiangoleosa (out of starting with 6). This one died back to the ground one winter a few years ago, and has since regrown to only about 4" tall!

And then I have a long list of failures including:

Survivor (this died late one spring after producing no flowers in the fall, so I think something other than cold killed it)

Autumn Spirit (it had repeated years with significant dieback so I finally took mercy on it, and sent it to my mother-in-law in NC, where it thrives!)

Also died are Snow flurry, Crimson Candles, Korean Snow (!), Kuro Delight, Winter's Charm, and Winter's Hope

I used to cover my camellias in the winter, but decided so stop doing that (except for maybe the first winter to let them get established). I've decided that I'd rather have plants that survive on their own cold hardiness, and not spend the time to coddle along plants that aren't hardy enough for this area.

I'll continue to try more. I've heard good things about Gov Mouton, so I'll likely add that next year. And also I'd like to try one of the camellias from the Morris Arboretum; Balustrade, Bloomfield, Morris Mercury and Meadowbrook (see this article Cold Hardy Camellias)