You could use stainless vertical posts with tensioned horizontal wire between the posts.

Either styles as per images would work equally as well.

Glass also ok but may be a continuous cleaning job.

Whichever design you go with aim for longevity.

I would suggest you refer first to the council requirements in your area for balustrade. My concern is that an inbuilt planter box is a structure that can be climbed. You may have to have an extra high balustrade to compensate for that.
What about a small wall and balustrade as per your photos, and then freestanding planter boxes.

Or I would suggest a traditional height balustrade either in a dark colour, so it disappears , or a glass balustrade. Then have your planters as small flower boxes attached to the balustrade or freestanding.

Sorry I have looked again at the sketch. Is the planter on the outside of balustrade? I would still go with dark colour or glass.
Also take into account eye level when sitting on balcony. Making sure the top rail of balustrade is not going to obstruct your eye level viewing.

MB Design, our neighbour have the tension wiring so would want to stir clear of that. :D Thank you for your feedback, makes me feel like I am on the right track.

dreamer, yes, the planter box is built in and is has a height to it, which means we only need a top railing to comply with standards. Looks like dark rail is the best one. Minimalist and thin. Wouldn't want glass because of the maintenance. Thanks for your suggestions.

Is the planter box in side of the balcony, hopefully not as built in and free standing planters are both climbable, as is alfresco furniture

siriuskey. the planterbox is build in on the top front and sides pf the garage/ The rail is going on the ninner box of the deck as per sketch.

I just wanted to confirm that the planters are on the outside and safe

To add to that, I believe that there's self cleaning glass available which I would prefer with your ocean view

To my eye, your home has a strong horizontal impression and a 'presence' in the streetscape

So the planter railings need to have that same 'feel'

I vote for the second photo to coordinate with the garage door, steps and screen at front door

Let us know how it is resolved - it's a good looking house!

siriuskey?? Really??? Self cleaning glass?? Will look into it, not as the rail but for the other parts of the house. :)

I'am sure it's now used for pool and juliet style balconies. Perhaps you could use it around the top of the garage to keep water views, unless you need a solid wall for privacy. Have you also considered how you will maintain the exterior planters.

https://www.enduroshield.com.au/glass-pool-fencing-balustrades/

http://www.nanoman.com.au/nanomanwindowandglass.html

https://www.clearglass.com.au/glass-types/self-cleaning-glass

siriuskey, i am not a big fan of glass balustrades. It would've been an easier option to be honest! And still keeping an open mind about it. We have hard wearing and low maintenance plant in the box, like agaves and other kind perhaps. We are learning from our neighbour whose planter above garage (but theirs is on the deck, different to ours) has gone wild due to the selection of plants. Maintenance? did mean something else?

access to the planter boxes, stones and snake plant are easy just need water. If you have a water view and no privacy issues, embrace the view

siriuskey, yes for sure those plants. I'll leave the maintenance to our gardener! He is very excited about it all. He is quite helpful with plant suggestions too.

Also on the coast.

Tilly, yes!! This is a better photo of what I have in mind. Would work right? Looks good? I am doubting myself. Thinner rails I guess it the key and of course black.

Tilly, thank you for sharing! Where are you based? How did you end up with this design? Custom made I assume. And how high are yours? Will keep your photos as reference!

Tilly, your house looks lovely! And would even save the plants selection for ours later! x

Bree we are in Safety Bay WA. The house was custom designed all I had to do was choose the style and colour.
I have added another photo so you can see they are on a ledge.
The height from the floor is just over a meter, the actual height of the rails from the ledge is 65 cm.

Thank you Tilly! It's good see how it looks like from that side. Beautiful views and hasn't blocked at all. And this is very close to what we are doing as well. The planter outside and have concrete bottom so we only need around 45-50 height for the rails. Much appreciated.