Best colanders for tree development?

[Forestcat]

I have some 3 year old junipers that I am digging out of a grow bed in order to put into colanders for further development. For other projects so far, I have tried a plastic kitchen colander with relatively small holes, tie-pots (with knobs around the outside that you can theoretically tie branches to), an asian plastic colander (small) with lots of small slit holes, pond baskets and fish baskets (used by fish mongers) with the same slits only much larger for some tall Japanese maple cultivars. I am considering S/S metal colanders this time around because I'd like to put less plastic into the world. The junipers are too small for large Anderson flats or wood grow boxes. Any thoughts?

 

[Brian Van Fleet]

I like the terra cotta colendars with a single hole in the bottom.
Of course you could always start with all 3 junipers in a single Anderson flat for a few years too. I have that going on right now.