I agree with Fiona about the Ficus - they have shocking root systems and should never be used near pools, houses etc. The width of your retaining wall from the photo looks really narrow, so you are going to have trouble growing most things in there; even the Pittosporums will eventually cause structural damage to the walls. The width of any garden bed should be ideally 1.5 metres at least for proper root establishment. This seems to be hard for most people to understand, but the bigger the plant, the wider the root system. So either widen the retaining wall or you will need to keep the plant lower. The pears mentioned also will never work. 5 years is the testing time of a good garden. When first planted they can look great, but they often break down as they grow. The Ficus and Pears' root systems will keep on expanding after the 5 year period with the Ficus having surface roots that cause massive damage to paving, concrete etc. Google it! And I have seen first hand the damage done by another Landscaper's work, based on inexperience. Get professional advice if in doubt - it is worth it if you get a good one. Alison

It is unfortunate that Ficus Hillii hybrids are being pushed by landscapers. The root system of all ornamental figs is bad. The Flash variety is just a smaller version of Ficus microcarpa which is a massive tree. They ALL have roots that cause severe structural damage to homes, pools, driveways, walls etc. As a very experienced garden designer, I have seen too many instances of considerable structural problems caused by this plant family. Beware.

georgi02 "follow some simple guidelines, the ones that people frequently aren't told when buying wall gardens and you end up finding out the hard way" Plant walls are fashionable and seem ideal for small spaces but it would be good if the stores that sell the bits and pieces told people it's not just a trendy decor item, it needs some gardening expertise. mutcherson, is there any space between that deck and the fence? IMO the most successful low-maintenance gardening is the right choice of plant growing in the ground. As soon as you start messing around with unusual plants, unusual containers, unusual locations, you start having additional challenges. But I reckon if you want it's worth having another try with a wall using georgi02 's instructions. Succulents are easy to grow from cuttings and forgiving of lack of water. When you take cuttings of succulents you are supposed to put them aside for a while before potting them and I have found pieces I forgot I cut weeks earlier and managed to grow them. I have had some problems with succulents but that was because of frost so you you won't have that challenge.

horizontal anything is a no, the gap would have to be so small it might as well be solid. yes the vertical cable might pass but you are not allowed to be able to squeeze them together as then the gap distance is non complying, The safest one is the solid section PCA pool fence, or glass, or solid, to 1200 mm in Queensland, no greater than 100 mm off ground, and gaps not able to be manipulated, and to stop that you have to have horizontal section in the cable type, which then do not comply, cut metal screens if complying is OK. I would question the void, and if you know the reason for the void, than solutions will be able to be worked out, now we are asking why? Pools in adjoining yards are acceptable with pool fencing complying on both sides, no void is required. so the void sound a bit iffy, unless it is something to do with storm water, or a building requirement, so ask the question why. Pool fencing can be awesome.