Opening this year's new ROR tridents

[Shibui]

It is almost middle of winter down here so I've started opening the new root over rock plantings to see what I've got this time.
Some of you are aware that I've developed foil wrap as a means of getting reliable ROR.
Young seedlings with flexible roots are positioned on the rock then the roots are wrapped in alfoil. Advantages are: it can be moulded to the shape of uneven rocks; Roots do not usually grow through the foil; Soil outside provides some pressure to hold the roots close to the rock; Provides consistently moist conditions so roots will grow in the space between rock and foil.

After the initial wrap the ROR starters are planted together in boxes and kept in the nursery for the first summer to allow roots to strengthen and grow out the bottom of the wrap.

The following season I plant them in the ground to speed up growth and thickening
If you could guarantee good watering you could probably go straight to the ground but watering is a bit erratic here so they do better under the watering system for the first season.
For the last 3 years I've been trying to develop good shohin sized ROR. They'll grow way too much in the grow beds and swamp the rocks so these will be grown on in pots to restrict the growth a bit.
Here are a few of this year's crop.

Even with some experience things still don't always work as expected. Note the root in the second pic that was folded and now grows back under another root. That would have been much better if it went around behind the rock. Experience shows that the one going under will start to lift the other root away from the rock and may even push the rock out of the roots as there's no good roots on the right side now.

 

[Shibui]

A few more from the same box

You may have noticed some of these have wire marks on the trunk.
In an attempt to get away from boring straight trunks on there smaller ROR I wired some seedlings and twisted them the year before. I managed to get the wire off some but a few grew too quick and swallowed the wire. The shapes are good and I think the scars have given some of these trunks a little extra character. Time will tell if the marks grow out enough to be good.

 

[SeanS]

Another great crop of ROR tridents @Shibui!
Your foil technique is by far the best, it’s the only method I use now and the results speak for themselves season after season!

 

[Shibui]

Some more:
This one still has the wire embedded inside the trunk. Scarring has definitely increased trunk thickness but will it ever look good?



Here's the difference when the trunks are tall and straighter.

 

[Shibui]

Make sure they are well wrapped. Roots that break out usually grow faster than those inside and can completely wreck the arrangement if left too long.

Fortunately this one hasn't got too big yet. Hoping I can rewrap and get it to grow further down the rock next summer.


This is the sort of root structure I aim for. Roots wrapped right around the rock so the rock cannot move or fall out. Also an interesting shaped rock rather than a smooth round one.



And here's why I don't bother doing many Japanese maples ROR.

Same age, same conditions but the roots have hardly thickened in 1 year. JM ROR takes at least twice as long as trident maple.

 

[TimIAm]

Last year I started a couple of trees copying this method. They seem to be doing quite well judging by how thick the roots are from the base of the trees.

I'm interested to know why this time of year is best to dig them up? Just trying to get an understanding. I'm guessing you are not doing any root pruning just setting them up for Spring?

 

[Jrmcmich]

These look good…how old of seedlings do you typically use? I have some small bare roots I got this spring that I put In small pots to grow some this year amd wondering if these would be good to use next spring to try ROR? They are currently maybe 3-5 mm diameter so not too large but I did some small trimming of tap roots before potting up. I did notice the roots definitely had some thicker sections but still not big but can see how tridents roots thicken relatively fast. Here’s a picture of a typical one I have. Just be nice to know if these could work or if I would be better off with younger ones?

 

[MMJNICE]

Really impressed ,,,and Really good idea for root over rock plantings I've never seen that Approach before. I have a bunch of silver maples that I'm going to try this on. American silver maples grow roots almost as thick as trident maples and grow just as fast. so I think this would work well for them as well. Japanese maples don't seem to grow with much Vigor in Ohio either, for me at least. Well at least compared to silver maples they don't stack up with speed of growth and root Expansion. I love to experiment with silver maples and have a root over rock planting with one,,,but now wished i used your Method on them from the beginning. Definitely next time I will. Your method looks much easier and almost full prof

 

[Shibui]

I'm interested to know why this time of year is best to dig them up? Just trying to get an understanding. I'm guessing you are not doing any root pruning just setting them up for Spring?

Digging involves root pruning. Repotting also involves root pruning. Not sure what 'setting up for spring' is?
Time of year is relevant to your particular location. I know I can dig, root prune or repot any time from leaf drop through to leaf out in my location. With years of experience I do not subscribe to 'best time' for anything. There are much wider windows of opportunity than most growers are aware of. It is just a matter of testing the boundaries for your particular circumstances.
I noticed that plant nurseries had bare root stock for sale soon after leaf drop and questioned why I, as a bonsai grower, was limited to digging, repotting and root pruning 'at bud swell'. The answer is obviously that I'm not limited to such a narrow window. Now I know I can chop roots any time from leaf drop through to leaf out with many species.

how old of seedlings do you typically use? I have some small bare roots I got this spring that I put In small pots to grow some this year amd wondering if these would be good to use next spring to try ROR? They are currently maybe 3-5 mm diameter so not too large but I did some small trimming of tap roots before potting up. I did notice the roots definitely had some thicker sections but still not big but can see how tridents roots thicken relatively fast. Here’s a picture of a typical one I have. Just be nice to know if these could work or if I would be better off with younger ones?

I typically use 1 year old seedings but that's only because they have roots flexible enough to mould to the contours of the rocks I use. Note that the wired and twisted tridents are 2 years old (1 year seedlings wired and twisted the applied to the rock in year 2) but those were probably severely root pruned when wired and twisted so the roots are probably only 1 year old. If you can mould the roots to the contours of your rock then the tree is the correct age. If the roots will not bend to follow the rock it is too old. I can't judge suitable material just looking at the above ground section though I probably would not use such straight trunk material for ROR - see a couple of posts back. Stiff roots may mould onto rounded rocks but probably won't go so well on more interesting rocks with hollows and contours.
Experience shows that 1 rock and 1 tree is not the best solution. I always have many rocks and many seedling options to find the best root/rock/trunk combination to begin with. Not every root structure will fit every rock. Not every trunk will sit well on every rock. Each new element multiplies the complexity of the arrangement. Trunk/ branches is hard enough. Rock/trunk/branches probably multiplies the difficulty factor by 10. Rock/roots/trunk/branches is probably 100 times more difficult to achieve than simple trunk/branch combination.

I love to experiment with silver maples and have a root over rock planting with one,,,but now wished i used your Method on them from the beginning. Definitely next time I will. Your method looks much easier and almost full prof

Any species that has roots that thicken quick can be used By all means try other species. Some plants have well behaved roots. Ficus and Chinese elm roots grow down and stay where they are put so I can grow those ROR without the foil (though it does add a little extra security) Trident maples just love to grow lateral surface roots. Without the foil they abandon the roots wrapped on the rock and grow a whole new set of roots just under the soil surface. Any of these I plant just a fraction too deep will grow new roots over the top of the foil which ruins the whole plan. i guess your silver maples are similar to tridents so the foil will be very useful. Make sure you have enough layers to stop the roots getting out before you can dig and check. In my soils the foil starts to break down after 12 months so annual replacement is important here.

 

[DonielDoom]

Fascinating stuff. Inspiring!

Thank you for sharing such valuable experience! Great photos and write up on a clever technique. Color me excited to put some rocks in the dirt.

 

[Michael P]

Thank you for all the information!

I am growing some Ficus microcarpa cuttings in tube pots in preparation for "root over trunk". The idea is to imitate the growth habit of strangler figs. How important is it to bury the foil-wrapped "roots over trunk"? Could you leave the foil exposed over the surface of the soil in a pot? The dead trunks I am using are too large to bury conveniently and then bring inside for the winter.

 

[Shibui]

The ficus I grow have a different root growth. They don't seem so keen on developing new shallow lateral roots so Just wrapping the roots and burying them seems to be enough to make the roots grow where you want. If you can manage enough humidity you don't even need long roots. Just place the ficus where you want it and roots will grow down the rock (trunk) all by themselves.

The reason for burying the foil wrapped roots is to have the soil put pressure on the foil and therefore press the roots closer to the rock to avoid those unsightly spaces between rock and roots. If you can't bury them deep enough there is no problem having the foil exposed above ground level. If the rock (dead trunk) is reasonably rounded I sometimes wrap the foil with duct tape. Duct tape is quite elastic so if you stretch it as you wrap it will tighten and hold the foil and roots right close to the rock surface.

 

[Jrmcmich]

The ficus I grow have a different root growth. They don't seem so keen on developing new shallow lateral roots so Just wrapping the roots and burying them seems to be enough to make the roots grow where you want. If you can manage enough humidity you don't even need long roots. Just place the ficus where you want it and roots will grow down the rock (trunk) all by themselves.

The reason for burying the foil wrapped roots is to have the soil put pressure on the foil and therefore press the roots closer to the rock to avoid those unsightly spaces between rock and roots. If you can't bury them deep enough there is no problem having the foil exposed above ground level. If the rock (dead trunk) is reasonably rounded I sometimes wrap the foil with duct tape. Duct tape is quite elastic so if you stretch it as you wrap it will tighten and hold the foil and roots right close to the rock surface.

I feel like I have seen raffia wrapped around roots as well? Have you ever tried that over foil for pressure?

 

[SeanS]

I feel like I have seen raffia wrapped around roots as well? Have you ever tried that over foil for pressure?

Raffia will have some gaps and it will break down through the growing season allowing roots to escape and grow away from the rock. Also raffia can’t be pressed into the holes and indentations usually found on interesting rocks.

I’ll post this one again, this was created using Shibui’s foil method. At the time of the last photo it was 3 seasons from seed. I have many more to share which highlight the foil method but I won’t derail Shibui’s thread

 

[Jrmcmich]

Do you normally remove foil each spring before repotting when first developing the ROR? Makes sense on raffia…thanks for clarifying.

 

[Shibui]

I feel like I have seen raffia wrapped around roots as well? Have you ever tried that over foil for pressure?

Anything that is not a complete covering will allow roots to grow through. It may work OK for species that don't grow new roots easily but not so good for tridents. Also not sure how quickly raffia rots in the soil. Binding that doesn't rot will constrict the growing roots and leaves ugly horizontal bands as the roots thicken. I avoid any narrow binding because of the marks left on the developing roots.
Wider binding is OK. That's why I now use duct tape but it will only be useful when the rock is rounded. Good rocks have hollows and crevices and only something flexible like foil can mould to the hollow parts and keep roots in contact with the rock in low spots.

Do you normally remove foil each spring before repotting when first developing the ROR?

Definitely check each year. The rate tridents grow and thicken you only have 1 year to reposition any roots that aren't right. Al. foil also degrades in soil. After the first year roots start to push through as the foil gets thinner.

 

[Shibui]

Started to dig the field grown ROR tridents.


These trees are 1 year older than the trees shown previously. That means 1 year in the grow bed and the seedlings are now 3, sometimes 4 years old. They have been on the rocks now for 2 years.
You can see they are still wrapped in foil to help contain the roots close to the rocks.
These are the next size up from the little ones show earlier in this thread. If I plant those shohin sized ROR in the grow beds they tend to swamp the rock with rapidly thickening roots so only the larger ROR go into the ground here. These larger rocks are better suited to slightly larger trees with more, thicker roots.

 

[gooeytek]

Those are some very inspiring results! Is it just regular aluminum foil that you use?

 

[Orion_metalhead]

Looking amazing. Going to try this with this years batch of cuttings!

 

[Shibui]

Is it just regular aluminum foil that you use?

At one stage I got hold of a catering pack of foil which was not only a bulk pack but also appeared to be thicker and stronger. Currently using ordinary household foil from the supermarket. Try to get the thicker and stronger foil if you have an option. It is surprising how easily a small root will pierce the foil while I'm wrapping the roots. Needs to be thin and flexible enough to mould into all the hollows and cavities of your rock without breaking while still strong enough to hold the roots on the rock.
Standard rolls are wide enough to fold the foil in half to wrap with a double layer on all but the biggest rocks. I still wrap with around 2-3 layers of the doubled foil. In 12 months the outside layer is virtually dissolved so having several layers is worth the little extra foil.

Some more of the field grown trees out this afternoon but a bit too late for more photos.