Juniper - how to progress after repotting

[Ozz80]

A month ago, I have repotted a pfitzeriana, a horizontalis to bonsai training pots and a nana to a larger pot with inorganic soil from their initial nursery pots. All have been bare rooted 50%. I also removed 20 - 30 % of the roots from pfitzeriana in order to fit to the training pot. I only cut some of the large and crossing roots from the other two. They all have dense foliage and have been stable after repotting Nana has a trunk thickness of 2.5 centimeters ( about an inch) at the base and I assume it needs at least 5 - 10 years of further trunk development. I am planning to start styling the other two meanwhile.

As long as everything goes well and plants keep healthy;

- Can I start lightly (half a dose maybe) feeding them this month? (I use osmocote exact 8-9 months for my other plants. )
- Can I thin them in this month or late summer / early autumn? (cutting inner growth and unhealthy / very thin branches, removing dead foliage, trimming downward shoots on the branches) without removing more than 5 - 10% percent of the foliage
- For doing major work on the branches of pfitzeriana and horizontalis, should I wait for 2 years, bareroot other remaining half with the nursery soil and repot and then wait for another year to style, or can I start styling next year in autumn?
- As far as I understand, making very small but deep wounds till the cambium tissue per half a centimeter with the tip of a scissor every month creates faster thickening at the base. Is there a downside of this method? Can I start doing this on the nana juniper next spring?

 

[Shibui]

Fertiliser no problem. I mix osmocote with the new soil mix so all my trees get fert right from repotting.

Thinning 5%-10% any time is no problem, even trimming this much at repotting does no harm. Retaining some long, vigorous shoots seems to assist with recovery after root reduction.

Usually no need to wait 2 years post repot to do further work but the tree does need to regain health after repot. That may take 3 months, 6 months, a year. All depends how severe the root reduction at repot, conditions after repot, time of year, etc. Take note of new growth to ascertain tree health and vigour rather than relying on the calendar. Further styling may be possible in autumn following spring repot but if the tree has not started to grow longer, vigorous new shoots best to defer planned work until you can see healthy growth.`

Wounding the bark can cause local thickening but not as fast as most of us would like. Be prepared to repeat this over and over for 3-5 years to make visible difference

 

[bwaynef]

- Can I start lightly (half a dose maybe) feeding them this month? (I use osmocote exact 8-9 months for my other plants. )
- Can I thin them in this month or late summer / early autumn? (cutting inner growth and unhealthy / very thin branches, removing dead foliage, trimming downward shoots on the branches) without removing more than 5 - 10% percent of the foliage
- For doing major work on the branches of pfitzeriana and horizontalis, should I wait for 2 years, bareroot other remaining half with the nursery soil and repot and then wait for another year to style, or can I start styling next year in autumn?
- As far as I understand, making very small but deep wounds till the cambium tissue per half a centimeter with the tip of a scissor every month creates faster thickening at the base. Is there a downside of this method? Can I start doing this on the nana juniper next spring?

-I'd begin fertilizing them.
-I'd thin them at your earliest convenience. I haven't found a bad time to do the thinning that you reference. The earlier you do it, the earlier buds can begin to develop due to the invigoration of the remaining foliage and additional light.
-If the trees respond like I think they will to the above 2 steps, I think it is possible that you could work them this fall. Then let them grow as normal next year (cleaning again, as necessary, and working again in the fall) before repotting in spring of '27.
-I've never attempted wholesale thickening of junipers by what amounts to scarring. I've never seen results that I consider convincing.

 

[Ozz80]

Thanks for the replies!