Collected english elm help.

[Dravic]

I had to emergency collect an english elm at the beginning of June that was growing between a kerbstone and driveway. Due to this the I could only save an extremely minimal amount of roots.

I thought it had no chance of survival in soil so I jerry rigged a dwc hydroponic setup consisting of a pond basket full of hydroton clay sat in a bucket of nutrient water and an air pump pinched from the fish tank which was placed in a shady spot in the garden.

After initially losing alot of its leaves it's now started pushing some new growth. A gentle poke around in the clay also revealed fresh root growth but I didn't want to dig too deep to avoid damaging any roots.

So my question is should I move it to a sunnier spot in the garden yet (forcast for the next week is sunshine and showers 18-20c) and also when should I pot it into proper soil?

 

[TomB]

I would leave it in the current pond basket and substrate, but take it out of the nutrient bucket. Stick a couple of bits of wood under the basket so the base isn’t in contact with the ground. Keep the substrate moist but not wet. Leave it in your shady spot. Give it a little weak fertiliser in a couple of weeks. Otherwise disturb it as little as possible. Repot next spring (probably April).

 

[Dravic]

Thanks for the reply, unfortunately I don't think (though I could be wrong) the hydroton will make a good substrate out of the hydro system, it has very little water retention and the particle size is large at 8-20mm. I'd be very worried about not only drying out but also frost freezing the roots when Autumn/winter arrive. Have you used hydroton as a bonsai substrate?

I've attached a couple of pics, the penny coin is about the size of a US Cent.

 

[TomB]

In the past I've used Leca pebbles about the same size, which is the same thing. It's OK for growing out stock. It actually retains water pretty well, within as well as between the pebbles. However if you're concerned at all, just put a layer of sphagnum moss or a finer substrate on top to retain the moisture. Any finer granular substrate like akadama or moler clay would work. You will do more harm than good trying to repot it now.
For an English elm in the UK, roots freezing over the winter should not present a problem.

 

[Dravic]

Ah ok cool thanks, it's good to know that I can keep it the hydroton as I really didn't want to repot this year, just thought I would have to. I have loads of moler clay here so I'll top dress it with a good layer of that.

What's your thinking behind taking it out of the hydro system now? My, admittedly noob, brain says loads of water, food and oxygen equals good conditions for recovery. I don't mean to be contrary I just like to know the why behind things.

 

[TomB]

I don't know of anyone who has successfully grown bonsai trees in a hydroponic system. It's fine for propagation but not long term. There's increasing recognition of the importance of the 'soil' microbiome (fungi, bacteria) for the health of trees. However I doubt it would do much harm to keep it going until autumn, if you wanted to.

 

[Dravic]

Ah I see, yeah the hydroponics was very much an oh shit panic solution rather than a long term solution. I'd imagine getting frozen solid over the winter wouldn't do it too much good.

I think what I'll do is keep it in the hydro system for the next month or so then do as you suggest towards the end of August or beginning of September when the worst of the hot weather here will have passed. Sound like a plan?

Would you at any point this year move it to a sunnier spot?

 

[TomB]

Maybe move it into the sun towards the end of August once the worst of the heat has passed and your new growth has hardened off.

 

[Dravic]

Cool, I think that covers all I wanted to know at the moment. Thank you very much for all your help. Very glad to know I can leave the repot til spring.