Slip potting into Bonsai soil.

[Ironbeaver]

Earlier this summer, I slip potted some newly acquired trees into larger, more suitable pots filled with bonsai soil. I didn't remove much of the old soil, just gave the rootball a slight massage and the loosest stuff fell off. To what extent will the potting soil around the old roots wash away/down to the bottom of the pots?

 

[Paradox]

It is impossible to answer that question. It depends on how root bound the tree was, how many of those roots were fine and tightly packed, what the old soil was and how compacted it is.

In my experience, you dont lose much but the details I mentioned above are probably different for each of my trees let alone yours.

 

[Ironbeaver]

These were rooted cuttings in 2 inch pots, put into 4 inch pots. Looks like they were in standard potting mix, not completely root bound. The surface area, mostly around the root base has washed "clean" I was just curious what I might find further down.

 

[Adair M]

Iron beaver, I cannot speak to your specific question without having been there when the potting was done. But I will address the issue of slip potting into bonsai soil.

First off, what I consider to be proper bonsai soil is a 100 percent inorganic mix of akadama, pumice, and lava. This is a very open mix. (Please, folks, let's not turn this thread into another soil debate. There are too many of those threads already).

Now, from what you described, your trees are probably in a nursery mix. Which has a lot of organic material in it. Probably makes a fairly dense root ball. Of soil. You may or may not have a lot of circling roots.

If you were to bury that into a pot of bonsai soil, without doing anything, you probably won't get any roots to grow into the bonsai mix. At least not very quickly. The two soil types are so radically different. The open bonsai soil is so open, the roots think they've hit air. And don't grow out into it. The water retention properties are radically different, too. Water passes straight thru the bonsai soil, and the nursery mix acts more like a sponge.

What will happen over time is you will water, and most of the water will pass through the bonsai soil so quickly that the old nursery soil doesn't get a chance to absorb much. Water seeks the path of least resistance as it goes to the bottom of the pot.

But most of the roots are in the nursery mix! Which will start to dry out from the inside out. So, what happens is your old roots get dehydrated, and new roots don't grow into the bonsai soil where the water is.

I suspect this happens to a lot of people. They get poor results, and blame the good bonsai soil. Erroneously.

Slip potting should only be a temporary "solution". If you MUST slip pot, use similiar soil to the original soil when you up pot.

The better solution is to REPLACE the old soil with new soil. You do this at the proper time to repot during the year. For deciduous trees, you can completely bare root them, wash away all the old soil and replace with good bonsai soil. For conifers, we cannot be as aggressive, so we use the "half bare root" technique. The following year, or maybe two, we do the other half. (I have described the half bare root technique in many other threads).

I hope this gives you some guideance.

 

[ColinFraser]

I have a couple of experiences that back up what @Adair M said - specifically with rootbound nursery stock in my case. Early on, I slipped several neglected 'Island of Misfit Trees' purchases out of their pots and into large tubs, surrounding the compacted rootball (mostly organics) with inorganic mix. After a slow and painful decline, I pulled the dead trunks out to see what was up. No roots in the surrounding mix at all.

Your cuttings may be a different situation though . . .

 

[Cypress187]

From my experience (killing tree's) you shouldn't count on washing anything to anywhere, you should have it in the right soil to begin with

 

[MaverickLancer]

I'd be careful about slip potting rootbound nursery plants. If they're really rootbound, you can get extreme cases of what Adair talked about. If you really must, it may be a good idea to soak the tree above the soil line to get water into the base if your tree is still in active growth. I did that once a week as a supplement to regular watering, but my soil was essentially a densely compacted clay by the time I inherited it.

 

[M. Frary]

When I slip pot rootbound plants up to a larger pot or when planting one in the ground,I just cut straight down 4 sides of the roots with a knife. Not deep,just enough to cut some of the outside roots.

 

[Adair M]

When I slip pot rootbound plants up to a larger pot or when planting one in the ground,I just cut straight down 4 sides of the roots with a knife. Not deep,just enough to cut some of the outside roots.

That's not really a slip potting, Mike.

But since we're talking about variations;

A good idea would be to tease out some fine roots 1/4 to 1/2 inch out of the sides of the rootball. Make it fuzzy on the sides. Then, when the new soil is back filled, the fine roots are already in the new open soil. They don't have to move out of the old soil into the new. They're already in it. And they'll find water when you water. This way they'll populate the new open soil fairly quickly.

But, that's not "slip potting" either.

 

[M. Frary]

Any way it's done you should score,cut,pull out or rough up the outside roots to encourage them to grow into the new soil.

 

[Stickroot]

Iron beaver, I cannot speak to your specific question without having been there when the potting was done. But I will address the issue of slip potting into bonsai soil.

First off, what I consider to be proper bonsai soil is a 100 percent inorganic mix of akadama, pumice, and lava. This is a very open mix. (Please, folks, let's not turn this thread into another soil debate. There are too many of those threads already).

Now, from what you described, your trees are probably in a nursery mix. Which has a lot of organic material in it. Probably makes a fairly dense root ball. Of soil. You may or may not have a lot of circling roots.

If you were to bury that into a pot of bonsai soil, without doing anything, you probably won't get any roots to grow into the bonsai mix. At least not very quickly. The two soil types are so radically different. The open bonsai soil is so open, the roots think they've hit air. And don't grow out into it. The water retention properties are radically different, too. Water passes straight thru the bonsai soil, and the nursery mix acts more like a sponge.

What will happen over time is you will water, and most of the water will pass through the bonsai soil so quickly that the old nursery soil doesn't get a chance to absorb much. Water seeks the path of least resistance as it goes to the bottom of the pot.

But most of the roots are in the nursery mix! Which will start to dry out from the inside out. So, what happens is your old roots get dehydrated, and new roots don't grow into the bonsai soil where the water is.

I suspect this happens to a lot of people. They get poor results, and blame the good bonsai soil. Erroneously.

Slip potting should only be a temporary "solution". If you MUST slip pot, use similiar soil to the original soil when you up pot.

The better solution is to REPLACE the old soil with new soil. You do this at the proper time to repot during the year. For deciduous trees, you can completely bare root them, wash away all the old soil and replace with good bonsai soil. For conifers, we cannot be as aggressive, so we use the "half bare root" technique. The following year, or maybe two, we do the other half. (I have described the half bare root technique in many other threads).

I hope this gives you some guideance.

This is the EXACT reason I developed my soil.
Oops I did it, sorry.
Over out.
MYCORRHIZAE!

 

[M. Frary]

MYCORRHIZAE

In everything? I've never used it myself. Heard about it. It's a naturally occurring fungus. My trees do fine without me adding it to the soil.

 

[Ironbeaver]

I plan on giving the roots a proper clean-out in the spring, the pots they were in were just too small (they were tipping over). Now, I have gotten a bunch of growth, the trunks have thickened. I've also been diligent in watering the old root ball so that it's not drying out. As I said before, the rootballs were small (literally a handful) I'm just curious about "what's going on in there?" Maybe I should have put at least one in a clear container to see if the roots are making it to the edge.

 

[ColinFraser]

In everything? I've never used it myself. Heard about it. It's a naturally occurring fungus. My trees do fine without me adding it to the soil.

Yep, just like you don't have to add moss to a shady spot, nitrifying bacteria and algae to an aquarium, or flora to your own gut - you can buy all of those, but they'll also just show up on their own.

 

[gjantzer]

Yep, just like you don't have to add moss to a shady spot, nitrifying bacteria and algae to an aquarium, or flora to your own gut - you can buy all of those, but they'll also just show up on their own.

Are you suggesting that adding Mycorrhizal fungi has no benefit because it will happen naturally?

 

[Vance Wood]

The big problem is the extent of the difference between the two soil mediums. If the two soils are close in structure slip potting should not be a problem, if as Adair has pointed out the one is heavily organic like many nursery soils slipped into a highly inorganic mix there is always the risk of root rot. One part gets too wet while the other stays too dry, the roots don't know what to do and rot in the confusion.

 

[ColinFraser]

Are you suggesting that adding Mycorrhizal fungi has no benefit because it will happen naturally?

Nop.