On a tangent to the original query: if you're game, you might try pleaching (grafting) your hedging plants--those of the same species. Normal hedges, where individual plants are planted quite closely together, compete with each other for nutrients as they grow. So if one plant sucks more water from the ground, it leaves less for its neighbour, which suffers. However, I've read that if the plants are grafted, they act more like one plant. If one gets more moisture, that moisture is circulated throughout the entire body of grafted plants and helps make them all stronger. Dunno if the theory works in practice, but it might be fun to try. (I intend to try it when my hedglings get large enough for their branches to cross.)

Hmmmm... looks like I'll be using a jackhammer a bit this weekend. I checked the location other two I planted on the weekend (the fourth is still in its bag) by driving a long starpicket into the ground - and there is at least a metre of topsoil available to them. Yes, we are reasonably close to the top of a ridge in hilly Lugarno in suburban Sydney, so the ground is naturally rocky in most places - having said that, there are some extremely large eucalypts around that seem to have no problem at all. Sigh - its hard to know when putting in the trees how big they will ultimately grow in their partly shaded position. It would be too bad if they never got to the minimum 3.5 metres that I need them to - but it would be a pain if they got much over 7 metres. I figured A.Smithii seemed to be the best choice - short of having a crystal ball. Is there anything I could do to try and predict their mature size - under the assumption that I can give them a good metre or so of topsoil? The size range on the web seems to be between 6 metres and 20 metres. I figure (and hope) that in a garden in Sydney, the norm is closer to 6.

Thought I would add our experience. In the week after Xmas 2010 ( temperatures in high 30s for the whole week) we decided to try and transplant 8 lilly pilly trees with trunks approx. 8 - 10cm thick, which had been kept pruned to about 2 metres in height and not sure of age. We didnt care if we ended up buying new plants but thought we would give it a go. We haphazardly pruned the trees back hard( one ended up with no leaves at all). We use a pick axe to dig a circle ( trench) out about 30cm all round from each trunk, soaked the soil with water and then used a pruning hack saw, pushing it down into the trench where ever we felt there was a thick root still holding on, then rocked tree back and forward until all roots snapped. The roots ended up shredded and totally bare of soil. The area we were moving them to was very dry with clay about 15cm down. We roughly broke up the clay in a circle just larger than the roots and added the only soil we had which was a sandy loam and some wetting crystals. We then stood the lilly pilly roots ontop of this and then mounded more sandy loam over the roots where ever they lay. We knew this would dry out too quickly so we used broken bark pieces (unused from wood pile) and piled this all over the sandy loam mound ( theory was to try and shade the sandy stuff). We installed a drip water system with a drip at base of each trunk ( We flatten the mound around the base of the trunk and pulled back the bark so water wouldnt just run straight off top of bark and down sides of mound). We watered the trees whenever we watered the vegies and every second day I sprayed the outside of the bark mounds ( theory - to keep them moist? ). We transplaned two murrayas ( spelling ?) at the same time in the same way. We decided to keep treating them like live plants until THEY showed us they were dead. Now... 1 month later, with more temps of over mid thirties ( even 40s) ALL of the plants have began showing new shoots up the branches with two even beginning to fruit again. The Murrayas showed new shoots within the first two weeks even though they were taken out last when we were totally fed up with trying to be NICE to the plants. As you can see... We didnt know what we were doing.. had no advice... and were not gentle. These trees just seem to live on and on. to anyone thinking about transplanting lilly pillies.. give it a go,.. you have nothing to lose.

I dunno, sometimes I type out a response/message press the right butoons, come back the next day and it hasn't worked. My fault or this sometimes unstable site? Anyway, I agree with Ted except I thought that black scale was 'hard' scale, not that it makes any difference the remedy is the same. My reference (Encyclopedea of Aus Gardening) says that native honey-eater birds usually keep the scales under control. Do you have any of those about, pennyw? B.