Dan, I would say 'out the back under a 50% shadecloth'. You may have to experiment with the percentage of the shadecloth though. Otherwise, if you mention which part of Australia you live in, some Bromnuts in your area may advise you what they found working best!

Japie

Without knowing what the light intensity is in your area, Dan, I'd go for the shadecloth option, just because even light conditions all day are better for even growth than a big fluctuation in light levels. 50% shade is more than enough light for most broms where I live, but you'd have to test it out to see what kind of results it gives you. Keep in mind that if there are trees around, it will be less than 50% light. You can also tinker with fertilizer levels if they're still too green.