What I have done on my terrasse for privacy is buy some big troughs (80 centimetres x40 x40), put 2 green metal poles (2 metres high) at each end of each trough and green plastic trellis between the two. I planted 2 ivy plants (ordinary ivy- hedera)in each trough and made them scramble on the trellis and within two years I had a solid green 'wall' of ivy nobody can see through. I only have to clip it regularly as it grows non-stop from April to October but that's no big trouble.
Don't know if that can be of any help but what I know is that when I wanted to create this screen, I was told to try and create a sort of hedge with conifers (thuyas) and that didn't work. I tried several options and finally decided on the ivy (after a walk in the countryside where I saw some wild ivy growing beautifully and thought it might make a good screen) and I haven't regretted it since.
Hope your deck is beginning to look nice and green
Greenfingers21

Thank you, greenfingers. A question: how did you attach the metal poles to the trough? Did you secure them with screws, or simply stick them in the dirt inside the trough?

My garden has now begun. I bought several bags of professional growers' potting mix and mixed it with topsoil and composted manure, adding Plant Tone organic amendment to the mix, topped with bark mulch. Found a nursery nearby with very reasonable prices. Went looking for cypress but decided I wanted traditional Southern plants that I couldn't grow before in the colder climate in the mountains, and I wanted perennials that I could 'harvest' for natural materials when I decorate for the holiday season. So far I've planted containers with 'Heavenly Bamboo' nandina (amazing winter color and berries), gardenia radicans (blooms and fragrance right now), acorus (sweet flag, gorgeous variegated foliage, strong vertical accent), and camellia sasanqua 'Setsugekka'(evergreen, fragrant, midwinter bloom, elegant semidouble white flowers). I'm aiming for garden additions that are visually beautiful and also attract wildlife and/or are fragrant.

But my real splurge was a 4x4 'Little Gem' magnolia, in bloom, espaliered on a trellis. It looks absolutely perfect against one of the privacy fences lining the deck, and I can see it from wherever I sit in my living room. I plan to plant annual vines at the base next spring and let them intertwine: purple hyacinth bean, maybe moonflower. I hope birds will nest in it next year. The garden already has hummingbirds zooming in and out (I put up a feeder) and a praying mantis has taken up residence too.

The deck is already getting full, so I really must figure out something, like baker's racks. to hold more pots. The only way to go is up. I'm sure that's a common problem on this forum.

Yes I simply stuck them in the soil/potting mix but, as they are quite tall and as it can get very windy on the fifth floor (storey in American English?), I secured them by attaching them to an existing metal hand rail that runs along the terrace and which came in very handy. I used screws to attach the poles to the hand rail and thin metal wiring to attach the plastic trellis to the poles. And as the ivy quickly grew into a really compact screen, you soon couldn't the attachments.

Your deck seems to be coming on nicely. Am pleased for you.

I personally was not very successful with cypress on my terrace but what grows wonderfully well in my troughs is
Chamaecyparis Lawsonia. We call them "false cypress" in French. They are a different species to cypress but very close to cupressus (cypress) but my experience is that they don't mind being in big pots/troughs contrary to cypress. they come in 3 different shades : green, bluish green or gold Another chamaecyparis which does well in containers is chamaecyparis obtusa. They are slow growing and look a bit like bonsaï as their shape is often a bit "distorted" but lovely and they are a nice dark green.
Hope I didn't bore you with my mail ... Keep the good gardening going.
Talking about birds, they seem to like the Chamaecyparis Lawsonia as they nest in mine almost every year. This year I had a nest in 2 of them and was able to watch the baby birds (is it 'fledgelings ?) learn to fly, a wonderful sight. They seem to know they don't risk much on our terrace : no cats to disturb them, only us and we try to be as discreet as possible when we watch them.
Hope I didn't bore you with my mail ... Keep the good gardening going.
Greenfingers21

Yes, Greenfingers21, false cypress is what we call it, and I think obtusa is particularly beautiful. That's a good idea, thank you. And no, your posts are not boring, quite interesting in fact. I have always been fond of Italian cypress as well but it will get too big, I think, and it needs a warmer zone.

Yes, we also call the floor of a building a story here. I can't remember, do the French define the levels as the English do? Ground floor, first floor, second, and so on? If you're in southern France, you have a wonderful climate for growing things.

OK, I'm getting off topic. Thank you for your kind wishes.