How to avoid juvenile foliage?

[Nick121]

Any tips or techniques in avoiding juvenile foliage working with junipers?

I have this Chinese Juniper (Montana Moss), pretty healthy with plenty of new growth, but the new growth are juveniles (needles instead of scales). From scales turning to needles.



I say all the new growth are needles.

A bit of plant work history....

I did everything at one go, which means... Cleaning (dead foliage, foliage growing down, etc.), Pruning (weak branches, branches i dont need), and wiring. All at the same day.

Since its my first bonsai, I probably removed a lot of plant material and stress the plant to a point of it reverting to juvenile? How do you work with your shimpaku or similar scale junipers? Do you prune and style your shimpaku in stages (perhaps across several season)? Lastly, how long would it take for the juveniles to revert back to scale foliage?

Thanks for any tips

 

[Colorado]

Yes junipers will do this as a stress response. For some varieties, it can be common after heavy work. I am dealing with this on a shimpaku also.

I don’t think there is much you can do about it, other than wait for it to revert back and then prune off the juvenile. Interested to hear if some of the more experienced members have any tricks for dealing with juvenile foliage.

@Brian Van Fleet @Adair M any suggestions?

 

[Brian Van Fleet]

Some varieties will often have some juvenile foliage, not sure about yours. Avoid pruning too much foliage off at a time, do not take more than 25-30% at one time until you find the right balance that won’t prompt juvenile foliage. Don’t pinch tips.

 

[Nick121]

Some varieties will often have some juvenile foliage, not sure about yours. Avoid pruning too much foliage off at a time, do not take more than 25-30% at one time until you find the right balance that won’t prompt juvenile foliage. Don’t pinch tips.

I think the "avoid pruning too much foliage" part is the part I missed when I started. I didnt realize that juniper would revert to juvenile when stressed. Lesson learned

So how do you work say an overgrown Shimpaku from a nursery when most of the foliage have to be remove? Montana Moss is similar in this sense, its pretty dense from raw material, just like a Shimpaku. Do you do your pruning and styling in stages?

What Im thinking is to get another Montana Moss.

1. Remove no more than 20% of plant material, which probably barely cover the clean up part, never mind the styling part atm.
2. Wire what I can, without removing foliage beyond the 20% mark
3. Continue clean up and maybe style a bit next season, removing no more 20% of plant material.
4. Repeat step 3 until final shape/style is achieve

Is this a sensible approach for such juniper?

Thank you

 

[Brian Van Fleet]

So how do you work say an overgrown Shimpaku from a nursery when most of the foliage have to be remove?

Start slow, and be methodical, branch by branch. Remove weak and yellowing foliage, and stuff growing from crotches of branches. Trim whorls of interior shoots back to pairs. Shorten strong runners by trimming them back to a new tip. That represents a likely 25%. When the tree recovers in a few months, it should be better balanced and ready for more work. Here is a post illustrating the process:

Itoigawa Shimpaku summer work

I last wired this one 2 years ago, and the wire was digging in. It had also gotten fairly dense, and as is the case, weak areas got weaker, and strong areas got stronger. So this work was to remove…

nebaribonsai.wordpress.com

Initial stylings where you end up removing more will likely result in juvenile foliage for a while, so that’s when you keep it healthy and let it grow strong, and then repeat the steps in the previous paragraph.

 

[Nick121]

It makes sense now. Thank you Brian

 

[Scorpius]

Thank you for that as well Brian. A picture says a thousand words.

 

[Crazy Diamond]

J. chinensis have a ton of cultivars and they are very heterogeneous, the high end japanese cultivars are very stable only producing needles when the plants are highly stressed. Then are the hundreds of garden cultivars; some are stable others will produce needles with pinching, some of them always will have a mix of scales and needles no matter what you do, and other only have needle foliage like the J. chinensis "Stricta"