Should I repot?

Hi everyone

I have recently posted in the forum Q & A 106 (00:33:17 - Gold coast juniper / Continuing work). Ryan’s advice was if coming into fall/early winter I am to leave the foliage alone but pot the tree in a bonsai container. However we are actually right in the middle of winter
Should I still repot and protect the tree from frost or leave the tree till spring and do more styling or do nothing until fall 2022?
Thank you in advance

I would wait until the normal spring repotting season now that you are in mid-winter. Of course the timing depends upon your seasonal temperatures.

I second that, wait 'till spring if possible.

Do not repot mid winter. There’s a reason why you repot in spring (and sometimes fall). You need two things for a successful repotting: metabolic activity and mild weather.

Spring is when the tree gets out of dormancy and the growth (auxin/cytokynin) cycle starts. It usually starts with root growth, as fine roots will inevitably become frost damaged and need healing, then the auxin moves to the branches where it drives foliar growth.

This presents an opportunity for repotting, as when your tree is actively growing roots, it will easily form a callus where you cut the roots and then grow new roots.

Fall is another possible period for repotting, because in the fall, with the loss of foliage, the tree focuses on vascular growth and that includes growing the root system. Weather conditions are also milder than in summer or winter, so the tree could still survive the operation.

However, repotting in the fall is riskier, because there’s only a brief window where that metabolic activity and vascular growth occurs, and your tree could be left with an underdeveloped root system and go into winter dormancy underprepared.

In winter, there are just so many things that could go wrong. The tree is already dormant, which means that it will most likely not form a callus, and in turn will not grow new roots. To add to that problem, its roots will have open wounds which can take in water and rot.

Now NZ winters are milder, but I’m sure it’s still not a smart choice to repot a fully dormant tree, for the reason I just mentioned. It’s not just about the cold and frost damage. Dormancy and the lack of metabolic activity is the real hindrance here.

That all makes perfect sense thank you
So come spring I should wait for the first flush of foliage growth to harden off right?
And going from a large nursery container to a bonsai pot what is the best soil mix for the best success?
Also ld like an opinion on which pot would suit the tree best

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No no. So, I don’t really do conifers (except for larch), so I’m not sure how obvious buds are on junipers, but with deciduous, you’d usually repot when buds start to swell. With junipers, I’d imagine you could repot a bit earlier than, but don’t quote me on that.

When I’m talking about spring and winter, I don’t really mean regular calendar spring and calendar winter. Actual spring starts earlier than the calendar season we call spring (climate change and all).

According to the “gardening calendar”, winter ends in February and spring starts in March (northern hemisphere, obviously). So the period from around March 1st to March 21st is what people usually mean when they say “repot in late winter/early spring” (again North hemisphere, so translate that to your own time period).

Again coming back to junipers, people have said that you can repot in February (last month of winter north), as long as the lowest temperature day has passed (you can see a day-by-day weather forecast for the month), and I’ve had success repotting a juniper that way too.

About the pot, I think all of those are too large, but the first one is best.

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Great thanks again. I was not sure how much of a reduction to give to roots going to the first bonsai pot and I still have plenty of time to find a smaller pot. August is the last calendar month of winter here and plants do tend to start growing before spring here also. I have an Ume plum in the garden in full bloom ( I intend to air layer this season)

As for the soil mix I have found I think the only supplier of akadama here so bought a few bags
Also have pumice , lava and pine bark

What ratio would you recommend ?

I can’t speak to soil mixes, as I don’t use typical bonsai soil material (there’s nothing readily available here in Macedonia).

However on the pot, on your first repot, you should reduce down to your final pot size, according to Ryan. That way you start refining the root system at the earliest possible stage.

Ryan also suggests to not bare-root junipers, but young ones like yours should be able to take it.

Thanks again. I will try and find a soil stream or thread and again the final pot size makes perfect sense too I will repost here when I have the repot done
Your assistance is much appreciated

For repotting time on junipers the changing color of the foliage from the yellowish, purplish to a more vibrant green is a good indicator that it’s time to make a move, it’s waking up. If unsure check the roots for whitening tips. You could remove one third or a bit more of the root mass with no problems, if you’re not exactly sure on what you are doing leave a bit more to be on the safer side.
I usually start with material like this, grown in a deep nursery container, guessing garden in soil, by lifting it out removing the top of the soil 'till I hit the roots, then I take a sharp knife and I cut from third to half of the bottom part of the root/soil mass, then comes the fun part with chopsticks.
A 1-1-1 ratio would work well for soil mix depending on how warm/wet it gets, water quality and so on. Check out the stream for soil recommendations.
And yeah those pots are way to big.
A usual size reference is pot lenght= 3/4 of the trees hight and for depth, that should be equalish to the thickest part of the nebari.
These are just rough guides that you could deviate from, so don’t take it literally :yum:

Thank you @Kenez that is a big help. Would you recommend a smaller version of any of the pots shown?

I’md probably go with the first one

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On the current large juniper stream, Ryan stated that 2-1-1 can work well for junipers, perhaps with refence to slightly drier climates. He also suggested leaving the 1/16" (i.e. sub 1/8" (3 mm) out for the initial and perhaps the 2nd and 3rd repots. This was for collected junipers where there is field soil to remove over a period of time. However, my experience with nursery stock is that the interior of their soil can be just as fine and compacted as in a collected tree.

As a side note, I have observed that in small size akadama I have gotten the 1/16 - 1/8" (1 - 3 mm) is about 25-30% of the amount of 1/8 - 1/4" (3 - 6 mm). As a result, I am using that ratio for all of the ingredients when making soil with the 1/16" left in.