No one have an informed view on this?

It's very hard to know when you haven't told us what your normal soil is like and where you are (gives us some idea of climate and rainfall.
What kind of soil/subsoil/rock etc is under that foot-thick layer of sand? Well-drained or not?
What on earth is "Bailey's soil conditioner" and what is is supposed to do? "Conditioning" is not a very helpful term. Why would you normally add it to soil?
Sheep manure sounds a bit strong for the natives you're planting, except perhaps for the lillypilly. You'd want to be rather sparing with it, and not put it within a foot or so of the roots.
Some plants don't like cement bits, because they make the soil a bit alkaline - but it does depend on how much of it there is in the soil.
Do you pre-soak your water crystals?
That's a tough-looking selection of plants you've planned. Why not just go ahead and see what happens - then let us all know. (The lillypilly will appreciate plenty of mulch, on such a thin soil)
Cheers,
Trish

Thanks for the reply Trish.

I guess I was assuming that Perth gardeners would be replying, and that there was no need to elaborate on soil conditions, but I should have made my locale clear.

So, it's a typical sandy grey soil area (Floreat Park), but as explained, this is not natural soil. It's leftover yellow builders' sand on the surface down to about 20cm or a bit more, before the 'natural' soil level starts.

Bailey's soil conditioner is a local brand that is made especially for our conditions, and is the choice of most native garden specialists. Yes, you add it to our generally impoverished local soil.

Yes, I pre-soak my water crystals - but I already know a lot about raising natives, and was not after advice on this. It's only this atypical yellow sand that had me concerned.

Sheep manure is fine for all the plants I have selected - tried and true, used it myself with success for years (but only in small quantities with natives).

And yes, I will be using 'enviromulch' (green tree prunings) on the lillypillies and throughout - again, well experienced with applying this in native gardens.

In the absence of advice to the contrary, I will assume that the yellow builders' sand is not intrinsically hostile and mix in some soil conditioner, use a pH testing kit to get a pH between 6 and 7, and all should be fine.

This doesn't appear to be a very well patronised BB these days, or perhaps it's just that there is not much interest in this situation - but yeah, I will report back progress in a few months.

Glad to hear from you, Innyanga. I really wrote because I was sorry to see you had had no replies - but as a gardener on a snuffy red clay soil, I'm most definitely in no position to be able to give you any useful advice at all!
We do get some good results here for some plants - generally the natives of granite areas - with river sand on top of our natural soil. But that's to do with a well-drained surface layer acting as a mulch for water retention deeper down, and is quite a different story.
I am interested to hear of your success with sheep manure.
Trish

Appreciate your response, Trish! Yes, our soils do sound pretty different! Doubtless both fine for different plants.

Re sheep manure for natives: this was a new idea for me when I first encountered it a few years ago at a native plant specialist nursery. One of the staff, who spoke at some length about her own native garden, said she always put a bit of well "matured" sheep manure in with her native planting mix, and had found that the plants generally thrived.

She reasoned that in their natural bush settings, plants inevitably came into contact with animal manures (eg: from kangaroos and other native mammals), and that there was no reason not to provide them with nutrients from similar sources in domestic settings. Sheep, of course, is one of the mildest of the animal manures, as well as having a good range of nutrients to make available as it breaks down. So, we tried it.

True to this lady's word, it's been fine. Guess we can file the "no animal manure for natives" truism with the old myth about natives not responding well to pruning! That said, I only use sheep sparingly, and wouldn't use any other type of animal manure on natives.

Cheers!

The plants you've named are all pretty hardy. All natives as you probably know love good drainage, so the sand would be ok if it's river sand, not beach sand, though I guess builders wouldn't use beach sand. No cement, of course, too limey. I grow my natives on fairly well drained red volcanic soil, some do better than others, however, a year or so ago I purchased nursey soil for natives - more sandier than their 'premium garden mix' - and all natives I've planted there: chamelaucium; grevillia; leptospermum; eremophilas; hibbertia, etc, etc., are all doing well.

I would like to add one more point that many of the most popular native plants sold in nurseries will not grow well in a clay soil. So one will be much more successful choosing plants for heavy soils rather than trying to change the soils for plants which prefer lighter soils.

Here is a link that might be useful: Bio Active Peat