AusBonsai

Hey guys, I am trying to air-layer my hawthorn. This is the third attempt, but each time it has developed big lumpy callouses after putting out only a few roots. Is there a way to fix this or just keep trying? Each time i cut off all the callous and start again. I am very careful to remove all the cambium (or so i thought) but the last two timesa large strip of callous connecting the bark down the tree has developed, as well as all around the top of the layer. So what can i do? Thankyou!

You can try and add a larger gap in the air layer so it does not heal as quick, I always wrap some string around the trunk and use that as the width of the air layer.

It might be better to try the Tourniquet Method if you google Air Layering Tourniquet Method you should get some more information.

I would leave the top callous in place otherwise the tree has to make it all over again. My experience has been that some deciduous trees are very reluctant to root and would rather bridge. I would make the lower ring lower to widen the gap. On some lems and celtis I have found I also put 2 wire torniquets in the gap and that can stop the bridging. Sometimes a lack of roots can mean the layer has dried out.

Thankyou guys, I will try adding a wire tourniquet or two. The gap is already one and a half to two times the diamteter of the trunk, as i had to extend it upwards to get rid of the callous. So Bougy, are the callouses needed for the tree to produce roots then? They are huge and very lumpy, and I've noticed the appearance of roots stops after this callous develops.

Usually the roots will form directly below the callous - it is an advantage in air layering as you get a nice basal flare straight away. If I have to rescrape I always just do the gap and maybe a bit of the bottom ring. If it has started to callous I leave it in place. Make sure it doesn't dry out - especially in summer. Have you used the cling wrap or split pot method ? And what medium are you using ?

Ok then, i will leave the callous then, I had no idea the roots came from it! Thanks, I wrap wet towels around the air-layer to keep it cool and moist, and i make small holes in the plastic so it seeps through. If it does dry out i use a drink bottle to squirt water in. I am using a zip-lock bag, i find the plastic is less likely to disintegrate after weather exposure, and tie it in place using string. The medium is spagnum moss.

Layering a Hawthorn is very difficult and i have had many attempts. For a weed they are very fussy about producing roots from where you want them. They will develop a bulb at the layer point and can live for 12-24 months on that alone. i am into my 5th attempt and i am trying it from a different angle this time. Sever the layer with its growth after 6 months or so and feed it with root promoting products such as Seasol, aminogro etc and leave it alone for 2-3 years. I have done this and my layer is still alive. It is also growing which is a positive sign. If you have ever dug Hawthorn you will find they hardly have a root system, instead they have long extended supple roots that take up the nourishment.

Thanks for that Bodhi, i will definitely leave on the bulb/callous then, if thats what it lives off. I would love to know how your technique turns out in the end, if it succeeds i may give it a go as well eventually really don't want to lose the top of the tree, as thats the nicest part for training as a bonsai!