I believe these trees grow quite quick, anyone know how long to reach this height?

There are several variables. In your picture the wall and the paved parking area would inhibit the growth,

so those trees could have been there for twenty years. The trees in the middle grow faster as they are competing for sunlight.

If planted as saplings 30 to 50 cm tall, in well drained fertile soil, with good water supply they could grow to that height in as little as 8 to 10 years. Longer if overshadowed by tall bamboo as are some of my trees.

Agreed. I planted five of these about 18months ago to break the afternoon sun. They were a bit slow to start with but have grown about two metres in the last 12months. They just seem to be spurting up quickly now and they love water .

Agreed. I planted five of these about 18months ago to break the afternoon sun. They were a bit slow to start with but have grown about two metres in the last 12months. They just seem to be spurting up quickly now and they love water .

The only thing I would advice you, is to initially plant these tree a bit closer together than a shown in the picture. That way, from a fairly early age, these trees will actually form a "green-barrier", without the large gaps in-between. I have always put these guys @ 2 meter intervals: works great ! !