AusBonsai

Hi, just a question about re potting, when I re-pot a tree normally I would leave a bit of the original mix around the root ball, if you are going to go from using normal Bonsai potting mix to using Diatomite, would you still leave some of the original mix around the root ball. ??
James

I would completely bare root only deciduous and only on first repot

Good question James.

Some of my figs I have bare-rooted, but in general I roughly rake the roots out, trim them, put the trees back in the pots and top up with new mix - working the new mix into the roots with a chopstick. I've re-potted some of my figs in a Diatomite mix (50/50), but I didn't bare-root them.

Earlier this year I re-potted my three large Crape Myrtles and those I did bare-root - even to the extent of using a high pressure cleaner on them - I found they still had some of the original garden soil close up to the trunks and I couldn't get it out by just raking the roots. They also got re-potted into a 50/50 Diatomite mix and they never looked back.

I'm under the impression that Conifers - including Junipers have a symbiotic relationship with a fungus called Michorriza that basically converts the nitrogen into a form that the trees can absorb. I've always been told never to completely bare-root them because they need the Michorriza to survive, and if it is absolutely necessary to do so, then add some of the old mix in around the roots otherwise you stand a good chance of the tree dying.

thanks Guy, G'day Taffy, how you doing mate, thanks for your reply, are you coming down to our meeting next weekend ??
James

Hi James,
The practice of leaving a portion of old soil in with the new I think mainly concerns the pine family Pinacae (Pines, Cedars, Larch, Spruce, Fir etc.). Not sure about Junipers, I dont bare root them in any case, I may recall reading somewhere that there is a symbiotic fungus involved with Beech and Oaks as well.

Cheers,
Mojo

Pines ( I only have JBP) i leave some of the original substrate in with the new mix
Deciduous Junis and most natives, I bare root and replace with fresh soil. I just give the m a light shake and the diatomite mix falls out, but i do not wash them out. ( Unless the first repot into diatomite. then I will give the roots a good wash)

Ken

I would imagine that your diatomite is a very free draining medium. If this is introduced around a more compact medium which is left in place, the subsequent watering has the drawback of draining straight through the outside and not getting into the centre of the rootball. It is better, particularly with the deciduous varieties, to clear out the dense part as well. By all means keep back some of the previous medium for symbiotic purposes for Pines etc. but mix it with the new material rather than leaving a compact centre. I hope that your pines are already in a very gritty medium as they should be.