I am growing a lot of my natives (50 or so) in 'pond pots' . During the summer I sit them on gravel beds and let the roots escape into the gravel bed . This technique is similar to RayM's ground growing in collanders . If I had seen his thread earlier I might of gone down that track .
You can tell when the tree has grown roots into the gravel bed by the rapid growth it starts to put on . I prune the roots that have escaped when I think it's getting to carried away . And at this time of the year I do all of the escaped roots whether they need it or not . My growing season is short in the mountains (this season the last frost was the second week of December and at the end of this week we are forecast to get down to 1 degree ) I need time for any new growth that happens with my pruning to harden off before the cold weather really kicks in .
During winter I put them in a cold glass house and
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When I chop the tops I like to leave some insurance ie extra branches till I see the new leader start to grow . I reckon I might have some trees worth showing in 5 years or so . These tree's are all seed , cuttings or bought tube stock . The Mel in the photo is tube stock with two seasons growth .
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. In spring when i chop this fella it back buds like crazy I rubbed everything I didn't want off and only kept the sacrifice branches on the base and a new leader plus the spare . The growth direction has now changed slightly because the spare bud was to one side but it's nice to think that nature is helping me create something 
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