root pruning out of season

[shibui]

I have done some further experimentation with out of season repotting this spring.
These trident maples have self seeded into other pots and needed to come out to allow the legitimate resident room to grow.
First candidate:

bare root trident 2015 10 1.JPG

This time I decided to really test the boundaries so cut the roots quite hard -

bare root trident 2015 10 2.JPG

but I did not cut the top at all, just watered it in after potting. Note that at this time these tridents are in full growth mode.

bare root trident 2015 10 3.JPG

And to further push the test it went back out onto the benches in full sun.

All the leaves went brown within a few days and I seriously thought it was going to die

bare root trident 2015 10 shoots1.JPG

but.....
3 weeks later new shoots are appearing

bare root trident 2015 10 shoots3.JPG

[Truth]

Interesting! Trident Maples are very hardy so I guess they'll really hold up to any abuse you can give them. I'd be intrigued to see how hard you could push Japanese Maples by comparison. I'm guessing not very hard...

[Isitangus]

The good news is if it survives this, anything less harsh should "theoretically" be safe!


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[Truth]

The good news is if it survives this, anything less harsh should "theoretically" be safe!

The problem with broad comments like this, is that these particular trident maples shibui worked on were young seedlings, which are full of vigour and growth strong and fast. If you were to do this to a full sized, old bonsai, stunted in a shallow pot, it would lead to a much worse story, and likely a prompt death.

[shibui]

The problem with broad comments like this, is that these particular trident maples shibui worked on were young seedlings, which are full of vigour and growth strong and fast. If you were to do this to a full sized, old bonsai, stunted in a shallow pot, it would lead to a much worse story, and likely a prompt death.

Thanks for pointing that out Truth. I have mentioned these factors in other threads on the same subject but did not put these riders in this one.
This experiment should not be taken as directions to treat any or all bonsai like this, rather as a starting point for further thought and trials.
1. As Truth points out, young, healthy trees react quite differently to older and unhealthy trees. (note that we have had other posts where experienced growers repot established bonsai in summer and autumn so more may be possible)
2. Trident maples are known to be far more hardy than many other species. (Note that Bodhi has already posted that he repots English elm in summer as well and we have also seen posts that other expereienced growers repot cedars and some other species mid summer so it does appear that other species can be repotted out of season)
3. This works in my conditions in my climate under my supervision and is a very small sample size. The same results may not occur in other places at other times.

The real point of the excercise is to dispel the myth that repotting while there are leaves on a tree is an automatic death sentence and to start others thinking about possibilities. I'd be very happy to see more experimentation and results posted here to add to our (currently limited) collective knowledge.

[bodhidharma]

Interesting! Trident Maples are very hardy so I guess they'll really hold up to any abuse you can give them. I'd be intrigued to see how hard you could push Japanese Maples by comparison. I'm guessing not very hard...

Now here is the perfect opportunity to experiment and test the water's Truth. Trailblaze and see how far you can push a JM. I have repotted JM in late September with no problem.

[Truth]

Interesting! Trident Maples are very hardy so I guess they'll really hold up to any abuse you can give them. I'd be intrigued to see how hard you could push Japanese Maples by comparison. I'm guessing not very hard...

Now here is the perfect opportunity to experiment and test the water's Truth. Trailblaze and see how far you can push a JM. I have repotted JM in late September with no problem.

I don't wanna.... I only have a small number of trees as material, and I don't particularly want to potentially lose them haha. Already lost a deshojo due to an over-fertilising accident this season.

[Matt S]

I once asked an experienced member of our club when was the best time to rootprune. Her reply: "About three in the afternoon". Another popular answer was "When you have the time and your tools are nearby".

In our mild climate I think you can rootprune any time of the year (other than sensitive species) as long as you look after them appropriately afterwards (bit of seasol, keep out of the wind etc). I still do my deciduous repotting at the traditional time simply because I think the odds are slightly better at that time of year. However I think the traditional reason for rootpruning in late winter (and one that particularly applies to short northern hempisphere summers) is that you don't interrupt the growing season.

Great experiment Shibui. You've confirmed what I've long suspected, at least with robust species.

Matt.

[Sean M]

It's been hot here in Canberra with a nice downpour last night, but I have had to dig up some plants due to the impending sale of the family home. One trident maple about 3 or 4 years old, several Chinese elm seedlings and a privet about 2 - 3 years old. They have been relocated to the shady side of the house and given a drink of seasol. I think they should be ok. They are all tough species.

[melbrackstone]

I'm loving reading these threads that suggest that our plants are not as precocious and difficult as we've been lead to believe....we do, mostly, live in a quite benign climate situation, and as long as we're not blind sided by some crazy weather event, mostly we should be ok with these kinds of root prunes and repots.

I'm unlikely to put a heavily root pruned plant into a full day's sun in my summer/early autumn, but other than that, I reckon a healthy young plant should be able to cope with just about anything, and after seeing what's been posted here, I'm much more likely to try just about anything!

Thanks again everyone, inspiring work.

[Sean M]

So just an update, all the plants survived. Not condoning transplanting your $4000 bonsai's in the middle of summer/winter, but with good aftercare transplanting should be possible (with some species) outside the guidelines.

[shibui]

Thanks for your update Sean. Bit by bit we are adding data to the existing store of knowledge. It is great to see others thinking outside the establishment box and trying new things. Keep it up guys

[Steven]

Today I reported a Black Pine, 3 Melaleuca, a Casuarina, 2 Tridents, 2 Japanese Maples and some small dwarf cumquat.
Last year I studied with a couple of nurserymen in Japan. I was told not to root prune and trim foliage at the same time. Their advice was that the roots recover better if the foliage is drawing up nutrients.
I'll let you know how today's lot go in a few weeks.

Regards
Steven

[shibui]

Great to hear Steven. The idea that plants recover better when you don't trim the foliage has been gathering momentum for a few years but I've been scared to try it

Grant Bowie has reported successful autumn repotting of several species, including more mature bonsai maples so there may be even more still to explore.

[melbrackstone]

DSC_0316.JPG

I root-pruned these tridents and placed them into a group planting just before Christmas 2016. One or two of the smaller trunks were shifted slightly a month later....and the tops of the trees were pruned at that time too. It seems very happy!