Sorry, I forgot to answer the questions. The Leucadendrons were in a greenhouse for the winter, but it did freeze in there a couple times. They can certainly take some frost but it's hard to say which ones might actually be semi-viable outdoors in our climate long-term. The Grevilleas, it really depends on which one - some of them are totally hardy, others not. The ones pictured in my second post are outdoors permanently in my garden and receive no protection, although it is only the second year for 'Poorinda Elegance'. Grevillea victoriae grows fairly fast - if you're lucky you might get a flower or two this year but I would say to expect a good show the following year.

In Holland you hae ideal conditions for growing cool climate banksias - sandy soil, relatively dry climate, etc. You will not grow warm climate banksias, or banksias that require an exceptionally dry climate. It's all a matter of selection - banksias require free-draining soil with not too much humidity. Read it up, select your species. Don't by any account use plastic covers over your seedlings - certain death! Tony ( My son lives in D.H. - I know the conditions - raised beds or pots might help - they don't grow well below sea level!!!)

Unless you are living in an area of savannah woodland I suspect a good diversity of native shrubs may have occurred on your site pre-clearing. There should be quite a few local natives, especially in your area (which I envy). I live on hard clay loam and have great success with Banksias and Grevilleas, but they're all species from areas with clay. I know quite a lot of the most popular WA plants come from deep sand so would doubtless kark it on clay. My past experience with Eucalyptus caesia (pretty much a shrub where I was in western Sydney at the time) shows it to be tolerant of clay, as is Grevillea biternata. Other WA species I am familiar with or have heard of taking well to clay include: Alygone huegelii Astartea fascicularis Boronia megastigma (well, maybe touch and go) Calothamnus quadrifidus Chorizema cordatum (if given a reasonable humus-rich topsoil) Eremophila - most seem to tolerate clay around here Hakea laurina, petiolaris Melaleuca coccinea (worth a try), diosmifolia, laterita Solanum aviculare (grows like lightning to about 2.5m) Some of the eastern natives (and are not too tree-like) that do well on clay in my experience include: Melaleuca parvistaminea, ericifolia, styphelioides Kunzea ambigua, parvifolia, ericoides Banksia marginata, ericifolia, spinulosa, robur, paludosa Grevillea hyrids of many sorts, aspleniifolia, juniperina Baeckia virgata Acacia species (most, especially feathery-leaved ones) Allocasuarina paludosa Atriplex nummularia Bauera rubioides Callistemon citrinus and cultivars Calytrix teragona Correa alba, reflexa cultivars Crowea all Dodonaea viscosa Prostranthera lasianthos, incisa, saxicola Philotheca myoporoides (used to be Eriostemon myoporoides) Indigofera australis Jacksonia scoparia Leptospermum, lots Myoporum montanum and various others Westringia longifolia, fruticosa Mind you, if you grow on limestone this list may be of sparse use. While most of these species are pretty hardy, some loathe high pH. Also, this list applies mainly to better drained clay (white or yellow to reddish) not soggy stagnant clay (grey). My personal preference would be your own local natives, you have so many real beauties.

I have quite successfully modified the growth habit of a few species. I have an Acacia pycnantha that I have successfully encouraged to grow with a clear trunk for 1.8m metres. Usually they have branches almost down to ground level. It was a simple matter of cutting off the lower most lateral branches right from when I first planted it as tube stock. Now it is about 4-5m tall and has not produced any lateral branches below the 2 metre mark for at least 2 years. It looks something like a mop top plant, though I do not bother shaping the crown. As long as you a vigilent with your pruning I don't really see why you could not encourage a similar growth habit with a Banksia spinulosa. Although it is more likely to be a case of 2-3 main trunks clear of lateral shoots rather than just one.