I think I've found the plant to happily occupy my trio of wall pots. If happiness is a flower, then my Vriesia bromeliads are happy here, as two of the three potted bromeliads, which I only planted here a few months ago as little baby 'pups', are already in flower.
This area gets zero direct sunshine, but stacks of filtered sun via the polycarbonate roofing of the pergola overhead, and the shadecloth on the western side. In summer it can get very hot and humid here, but it's sheltered from all cool southerly and westerly winds. It's a spot that suits the tropical/subtropical broms to a tee. Never sunny, never cold, occasionally stinking hot and humid – just like its South American home!
I had tried New Guinea impatiens in these pots, but they were so thirsty that the slightest inattention to watering led to instant wilting, and a wilting plant is just such a pathetic, sad thing to come across regularly that I pulled them out in disgust. Then the pots lay empty for part of the summer, as I pondered what to plant there. It was only when I decided to repot my bromeliads, and had too many 'pups' (baby broms) and not enough pots on hand to put them in, that I (thick as a brick) finally thought of the wall pots. It turns out that I should have had them in wall pots all along. In the wild broms don't grow in soil. They mostly cling onto tree branches or, sometimes, rocks. And so the small amount of soil in a narrow wall pot isn't a problem for them at all. The potting mix I use is the one our magazine suggests: 50:50 orchid bark and ordinary potting mix. Seems to work OK!As for care, they're dead easy. They do like to have some water in their little central 'cup', but it doesn't have to be constantly full or topped up. During our cooler temperate winters they like to be kept on the dry side, and during summer they like things on the moist and humid side. I sprinkle some slow-release fertiliser around them, and that's it. I guess I'm watering them about twice a week now, in autumn, and it'll be down to once a week in winter. Overwatering in winter is a really good way to kill them (a bit like indoor tropical plants, come to think of it.)As I mentioned earlier, these wall-potted plants were planted as 'pups', new plants which spring up from the sides of the parent, from the base of the plant. I waited until the pups were about one-third the size of the parent plant, then cut them off with a knife, trying to take some roots with each pup. After sending up its litter of pups the parent plant dies off (I'm not sure if that bit is true to all broms or not, but it's true for the few broms I have, Vriesias and Neoregelias.) And so an occasional routine around here is unpotting, dividing up, and repotting the pups (but if you don't get around to this, it doesn't matter, the pot will just be chockers with pups growing into adults). Each time I do my repotting the number of plants has steadily grown. Hardly any die, so the way I keep the numbers of potted plants down is simply to give some away. So if you see a bromeliad and are tempted, or someone who already owns some offers you a freebie, take it. Find a sheltered spot away from too much direct sun, such as a wall under a balcony or pergola, install some wall pots, and give amazing tropical bromeliads a go. There's only a zillion to choose from, so you'll probably find a couple of dozen that you'll adore.