What is it about me and Juniper roots?

laen ssor

I have this problem with developing a nice rootball on junipers. I have read and tried just about everything and I can't seem to get it right.
I have tried taking off half the old root mass from nursery plants, disentangling the remaining roots and planting them into good free draining soil. What I end up with is lots of fine roots at the tips and the entire middle of the old root mass turns black and die. Then I remove some of that, sparingly and trim back the new growth just a tad to ensure there is enough to sustain the plant and what happens? The new root growth extends but the inside still remains dead with no new growth. So what I end up with is an ever increasing mess of stringy roots that at this rate won't even make into a bonsai training pot.

Then I have tried cutting wedges into the initial root mass and replacing those areas with good soil. The old roots extend and the areas I removed the old dead compacted soil remain dead with no new roots. Same situation.

So what do I need to do to encourage new healthy roots close in to the trunk?

None of my junipers are showing signs of distress, they all have healthy new growth and are doing fine. I just can't get the roots to cooperate.

Mind you I don't have any problems with any of the other species I work with. My trident maples have nice rootballs, my hornbeam, boxwood, elms, and my sequoia are developing nice healthy rootballs. So what gives with junipers?

If I don't get help here I am calling Dr. Phil!

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cato42

...I might suggest you call Alex Haley. Ooh, except he's dead. Never mind.

The only real suggestion I've got is to be less aggressive at any one time in cutting back the central root mass; perhaps you're cutting it too far back? I'm not at all sure of this, but it sounds plausible, I think. I've always been fairly timid with roots, though, never taking off quite as much as I think perhaps I could, as I'm reluctant to kill the trees, inadvertently or not.

Well, good luck. If you discern what the problem and solution are, please post for us, I'd like to know.

Good question.

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Vance Wood

How long are you waiting before you cut into the root ball again? Junipers should not be disturbed in cycles closer than three years. They sometimes can be slow to develop good roots and if you are distrubing them every year they don't have a chance.

Bart Thomas(deceased)

Valuable answer, Vance. Funny this should come up....

I am working on the cascade shown in the Which do you prefer? thread, and was thinking similar thoughts.

When I got the tree, it was severely root bound in a nursery pot. Because it had been though a lot of stress, I simply teased the outer roots and put it in a larger pot with bonsai soil, jabbing some holes in the surface with chopsticks to help water penetrate.

Last year (after my first winter with it), I put it in its present pot, removing two "pie slices" with a saw, as the root ball was nearly impenetrable.

This year, I needed to shift its pot position (I was making potting angle changes.) and, when I took it out of the pot, I noticed that the formerly pot bound sectors had loosened up nicely. I also noticed little new root growth in the areas of the pie slices.

You have confirmed my decision to leave the roots alone this year, except for the "slip" potting. Once in place, I'll leave it alone for the next three years.

laen ssor

Vance,

I was repotting every two years but maybe I should go another year before touching them.

The thing is, when I did repot there was nice healthy growth at the ends of the existing roots but nothing further back. If I let them go will they continually extend or will new growth eventually start in closer to the trunk?

If I do need to let them grow 3 years between repotting what should be my plan of attach to get the growth in close to the trunk?

I appreciate your help.

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Newt

The first thing I do with junipers from the nursery is to take a saw or kitchen knife and cut the bottom 1/2 right off. Then loosen the surface soil, find the nebari and loosen the soil/roots around the entire root ball, top and bottom. Then take out the wedges or remove half of the remaining soil. If you don't cut the ends, you will never get roots in near the trunk, just make sure you leave some fine feeder roots, kind of like chasing the foliage back on a juniper or ficus too little branch. Then in three years the half that you removed the soil from should be left alone and bare root the other side, cutting the tips as much as possible while leaving some fine roots, remove all long roots. Long roots are useless in a bonsai pot, in nature they are used for ancorage which is accomplished with wire or twine in bonsai. If the long roots keep getting cut off you are only left with feeder roots.

Remember junipers are very tough and can take aggressive root reduction (as long as the top has been reduced as well).

Newt

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Vance Wood

Newt has summed it up pretty well, I endorss his methods on this one, and it is pretty much what I do. If you do not cut the ends there will be no development in the middle.

I think you are tending to treat your Junipers like you treat your other stock. Junipers have to have a recovery period of a season and a period of development, another season, and then they can be played around with again. I have noticed with my Shimpakus that they tend to look a little less than stellar the first season after repotting. The next season they go for the cheap seats and are back to normal.