Leaving Air Layers On?

[Gr8tfuldad]

I have a few air layers that have not produced an abundance of roots. First frost usually is somewhere between Halloween and mid November. With the narrowing window to harden them off, I’m wondering what is the better path. Take them now with low amount of roots or let it stay on the tree over the winter? I have never left an air layer on so I am not sure if there is risk in that as well. My initial thought is that they are highly freeze susceptible in the air, but maybe I’m not seeing the added benefit to leaving it? Thanks for your insight. The two that concern me the most is Sharpes Pygmy and Shishagarshara.

 

[pandacular]

I had a similar issue and posted about it in this thread. Didn't get much discussion about spring vs fall separation, but Jeremiah Lee recommended waiting. From other reading, some others suggested that a freshly separated layer is harder to protect than one left on the tree. I still plan to protect over the winter.

 

[KateM]

I wonder if you can put some bubble wrap around as frost protection? I have an airlayer that is not growing roots yet. Interested in this topic too.

 

[pandacular]

I would be surprised if bubble wrap does much for cold protection, but if folks have had success with it, I'd love to hear it! My plan was to just get a bigger pot and fill it with pine bark chips, similarly to how trees are often protected on the ground or in planter boxes.

 

[namnhi]

I don't recommend that as I have root rot over the winter on a couple I leave over the winter. If it has roots, I would remove it... as winter there really isn't much demand for water as the tree is in dormancy.

 

[pandacular]

I did some searching on the forums* and turned up a few useful threads, as well as this article by Harry Harrington. Quoted section below is from the article.

Protection for Airlayers

There seems to be general panic where the Winter and airlayers are concerned. The cold and frosts will not damage the airlayer itself. The airlayer itself is just a wound that will have callused over. You don’t pamper a wound from a recently removed branch during the Winter so why an airlayer?
Any new roots that are already growing from the airlayer will be more susceptible to extremes of cold in the same way as roots in a small bonsai pot are. However, they are insulated in sphagnum and plastic (you can add a layer or two of fleece or bubble wrap if you wish). If the new roots are damaged or dieback during the Winter, they will be replaced in Spring when the parent tree starts growing again.

New trees (produced by airlayers) should be separated at least 6 weeks before the first frosts, this allows the new roots enough time to grow and strengthen before Winter. If there are insufficient roots on an airlayer to separate it from the parent plant in the Autumn, leave it until the following Spring.

worth noting that Harrington is from south east England, so a different climate than New Jersey.

also worth noting that many, including our wonderful leatherback, disagree on the idea of leaving a layer on.

Finally, there is usually a big push of roots in mid fall, so I wouldn't make any decisions until you've gotten a clear picture of what you're working with.

*aside: searching using Google with "site:bonsainut.com" is MUCH better than the default search

 

[Gr8tfuldad]

I know had two air layers that did not root but calloused on my sharps Pygmy last year. I left them over the winter, opened in spring scraped callous and put rooting hormone . One broke bud and died the other made it a few more weeks and went the same direction.
I am thinking of leaving them a bit more and then separating. I will do my best to protect them over the winter.
I remember hearing Ryan Neal using 41 degrees as the magic number. What happens at 41? I ask because because I wasn’t certain if I should be protecting from 41 or 32? Thanks …

 

[BrightsideB]

I am keeping a couple on over winter on my shishigashira. I removed a couple late before and didn’t have good results the following year. But I didn’t protect them well from frost. Only the elite specimens survive my care lol!

 

[Dav4]

If you have some roots now, you'll have a fair bit more in a month. I'd remove the layers in late September.

 

[Gr8tfuldad]

If you have some roots now, you'll have a fair bit more in a month. I'd remove the layers in late September.

Is that a safe number? Eight weeks after separating for roots to harden off?

 

[Shibui]

Eight weeks after separating for roots to harden off?

What does roots harden off mean?
Sometimes we base our theories on poorly understood ideas.
All roots have young tips. That's the bit that does all the work. If root tips can survive winter why can't young roots from a layer? - given similar conditions/ protection

Trees here do not have to cope with the same cold as yours but I've regularly been surprised at how few roots a layer can survive with. I suspect that just the fact of separation makes the new tree put even more effort into developing enough roots to survive - but that's just another unfounded theory just based on a few observations so take it or not.

 

[Gr8tfuldad]

What does roots harden off mean?
Sometimes we base our theories on poorly understood ideas.
All roots have young tips. That's the bit that does all the work. If root tips can survive winter why can't young roots from a layer? - given similar conditions/ protection

Trees here do not have to cope with the same cold as yours but I've regularly been surprised at how few roots a layer can survive with. I suspect that just the fact of separation makes the new tree put even more effort into developing enough roots to survive - but that's just another unfounded theory just based on a few observations so take it or not.

As always your words carry much value. Thank you for contributing to the conversation.

 

[Dav4]

Is that a safe number? Eight weeks after separating for roots to harden off?

Where winters are cold, mid to late September is a great time to plant/transplant trees in the landscape because the summer heat has broken and heat stress isn't an issue. The same goes for layers- less heat means less stress for trees with marginal root systems. As long as the soil temperature is above 40 F, the root system will be active and continue to grow. 8 weeks post separation allows your layer to settle into the new pot and go dormant naturally. When the time is right for your climate- late November?- winterize the tree in a protected area with bark mulch covering the pot. The soil will likely freeze a few times before that, and maybe after as well, but the tree will be fine as long as the soil is protected from severe cold.

 

[PaulH]

I've often left air layers on over winter and usually have to re-cut the next year, However we seldom go below mid 20s F in winter.

 

[MSU JBoots]

I know had two air layers that did not root but calloused on my sharps Pygmy last year. I left them over the winter, opened in spring scraped callous and put rooting hormone . One broke bud and died the other made it a few more weeks and went the same direction.
I am thinking of leaving them a bit more and then separating. I will do my best to protect them over the winter.
I remember hearing Ryan Neal using 41 degrees as the magic number. What happens at 41? I ask because because I wasn’t certain if I should be protecting from 41 or 32? Thanks …

If I recall correctly he referenced that temperature for when metabolic processes slow way down and the tree enters dormancy if at or below that temp for long periods of time. I would have to look back at my notes but I think it was 25 deg or so when he really worried about protecting roots due to freezing.

As for the bubble wrap I have no experience. However, it won’t protect them from the cold as much as it would potentially buffer the layers from large swings in temp fluctuations. To that understanding is why I heel my trees in the soils for winter. The roots still freeze over the long Michigan winter but they stay frozen rather than freezing and thawing over and over again. At least that’s what I’ve learned.

 

[Gr8tfuldad]

Thank you everyone for your input on the subject. It has made my path clearer.