Post-root pruning root rot

[Lazylightningny]

This has been a constant problem for me. Scenario: I have purchased a plant from Home Depot. It's healthy. Let's say for the sake of argument that it's a cotoneaster, but really this problem is for every type of tree. Let's say it's April. I prune the top, saw the root ball in half and prune the circling roots. Repot either into a cut-down nursery pot or pond basket. Doesn't much matter. Invariably, the pot will remain heavy for weeks, months, with root rot at the bottom. I've tried withholding water, over-watering (intending to wash out fungi). I've tried keeping them in the shade, and keeping them in the sun. I realize this depends on species and other factors, but it is a problem that plagues probably 70 % of my plants. When the problem is serious enough, I have to unpot them, prune the root rot as best as possible, and plant them directly into the ground for a year or two to regain strength.

What do you do?

 

[just.wing.it]

I bare root completely the first time around....it will either love the new substrate and reward me with vigorous growth, or die....or mope for a season then rebound.

 

[Lazylightningny]

I bare root completely the first time around....it will either love the new substrate and reward me with vigorous growth, or die....or mope for a season then rebound.

Thanks Wing. How long have you been doing bonsai seriously?

 

[just.wing.it]

4 years.
And I've had good luck with bare rooting yews, BC, elm, crape myrtle, ewp, maples, junipers too...
The one that I've had a less that 50% survival rate is Azalea...which sucks because I love them so much...

But I have 4 now that are getting somewhere!

Edit:
I think it's best to Half Bare Root for Mugo or juniper, for safety.

 

[just.wing.it]

@Lazylightningny
Hey I've always wondered about your name here on the site...is that a reference to this?

 

[Anthony]

When we re-pot on this side, we remove an inch all around sometimes
an inch and a half.
Trees can be 18 inches down to 1 inch. Please factor in sizes.
After cutting off, we then comb lightly for any encircling roots that
might have been missed.

New soil mix and a through soaking.

Placed in a bright light zone. Watering is by observation, normally
in the bright light/ no wind zone. Water is usually needed at the end of
7 days.
After a week, trees are placed back in sun, early in ther morning.
Watering then goes to twice or thrice a week. Observation.
By week three, watering is back to normal.

Things to note-

This is our winter period.
No rain.
Temperatures can be 66 deg.F or higher at night from as
early as 10 p.m. until 8 a,m. For January, February and a week or two in March.
Daytime can be high 80's to a max of 90 for 30 minutes to 10 minutes
during the day. That is deg.F.

Soil has compost [ holds 20 times weight in water ] at 1 to 3 parts.

No fertiliser for a month.

Doing this for 39 years.

One change to come -------- older books say bright light for 2 weeks.
Observed a local ficus ------- up rooted after 1 week of transplanting - no new roots.
up rooted after 2 weeks - roots galore.

Wonder which smart dummy changed the practice ---- probably the impatient.
Good Day
Anthony

 

[Solaris]

This has been a constant problem for me. Scenario: I have purchased a plant from Home Depot. It's healthy. Let's say for the sake of argument that it's a cotoneaster, but really this problem is for every type of tree. Let's say it's April. I prune the top, saw the root ball in half and prune the circling roots. Repot either into a cut-down nursery pot or pond basket. Doesn't much matter. Invariably, the pot will remain heavy for weeks, months, with root rot at the bottom. I've tried withholding water, over-watering (intending to wash out fungi). I've tried keeping them in the shade, and keeping them in the sun. I realize this depends on species and other factors, but it is a problem that plagues probably 70 % of my plants. When the problem is serious enough, I have to unpot them, prune the root rot as best as possible, and plant them directly into the ground for a year or two to regain strength.

What do you do?

How much of the top are you leaving when you prune?

What are you repotting into, substrate-wise? Are you putting the pots so that the substrate is in direct contact with the ground, so the water in the pot can trickle down?

 

[sorce]

Yes
soil?
Pics?
Nursery soil left?
Barerooted?

For me...in that scenario...
April is the culprit.
July...no problems.

Sorce

 

[Lazylightningny]

@Lazylightningny
Hey I've always wondered about your name here on the site...is that a reference to this?

Come on dude, you're flying the Steal Your Face colors. Where else would Lazy Lightning come from? Great Bobby Weir song.

 

[just.wing.it]

Come on dude, you're flying the Steal Your Face colors. Where else would Lazy Lightning come from? Great Bobby Weir song.

Hahaha!
Just curious!

 

[Lazylightningny]

4 years.

Reason I ask is that I've been doing this for 5 years, intense, like 50-60 plants per year, and it's still a problem. Not is all cases, but still in many. New nursery plants, pruned in the spring, root ball sawed in half, pot stays perpetually heavy.

No offense, but if any more experienced members have a viewpoint, I'd love to hear it.

@Solaris, yes when I feel the heavy pot is a problem, I cut off the bottom of the pot and place it on the ground to facilitate draining.

 

[0soyoung]

Sounds to me a lot like the nursery soil has collapsed. That is, the air filled porosity has gone to zero and that the exact same result would have occurred had you done nothing. Normally, garden center nursery stock will be planted in the ground soon after sale. Roots then grow into the surrounding soil so the soil in the pot doesn't matter (b&b mud is an extreme example).

If I am reading the OP correctly, @Lazylightningny, you are not providing a good medium for roots to grow outside of the original organic nursery soil by either potting up and back filling with substrate or partial/total removal of the old soil and replacement with substrate.

 

[ysrgrathe]

Bare root next spring, or half bare root for conifers. Never mix old and new media (other than HBR), it is asking for problems.

However, if you can't keep them alive until repotting season, either you are doing something wrong or you need to buy from a better nursery. I water bonsai multiple times a day, but if your trees are in bark they may need as little as once a week. Root rot = too wet.

 

[just.wing.it]

Reason I ask is that I've been doing this for 5 years, intense, like 50-60 plants per year, and it's still a problem. Not is all cases, but still in many. New nursery plants, pruned in the spring, root ball sawed in half, pot stays perpetually heavy.

No offense, but if any more experienced members have a viewpoint, I'd love to hear it.

@Solaris, yes when I feel the heavy pot is a problem, I cut off the bottom of the pot and place it on the ground to facilitate draining.

No offense taken, ever!
No worries.
But I speak truth.

 

[Stan Kengai]

This has been a constant problem for me. Scenario: I have purchased a plant from Home Depot. It's healthy. Let's say for the sake of argument that it's a cotoneaster, but really this problem is for every type of tree. Let's say it's April. I prune the top, saw the root ball in half and prune the circling roots. Repot either into a cut-down nursery pot or pond basket. Doesn't much matter. Invariably, the pot will remain heavy for weeks, months, with root rot at the bottom. I've tried withholding water, over-watering (intending to wash out fungi). I've tried keeping them in the shade, and keeping them in the sun. I realize this depends on species and other factors, but it is a problem that plagues probably 70 % of my plants. When the problem is serious enough, I have to unpot them, prune the root rot as best as possible, and plant them directly into the ground for a year or two to regain strength.

What do you do?

Are you using a "drainage layer" in the bottom of the pots? A big differential in soil particle size (like when drainage layer is in contact with small substrate or when larger substrate is in contact with nursery soil) can actually cause the smaller substrate to retain water and inhibit proper drainage. I don't use drainage layers (though I do not have any large trees) because I have seen first hand that roots do not tend to grow in them.

 

[Lazylightningny]

Sounds to me a lot like the nursery soil has collapsed. That is, the air filled porosity has gone to zero and that the exact same result would have occurred had you done nothing. Normally, garden center nursery stock will be planted in the ground soon after sale. Roots then grow into the surrounding soil so the soil in the pot doesn't matter (b&b mud is an extreme example).

If I am reading the OP correctly, @Lazylightningny, you are not providing a good medium for roots to grow outside of the original organic nursery soil by either potting up and back filling with substrate or partial/total removal of the old soil and replacement with substrate.

In most cases, I simply saw the root ball in half, remove the circling roots, and repot as is back into the nursery pot. In some cases I will remove a little more of the nursery soil and repot into a pond basket, backfilling the empty spaces with bonsai soil. In all these cases, I am leaving the original nursery soil.

That's not to say that I don't sometimes bare root. Plants that I do bare root tend to do well, but you can't just make a blanket statement to bare root all plants. As someone said here on BNut, "It depends." But maybe I don't have a good grasp yet of what it depends on.

 

[Lazylightningny]

Are you using a "drainage layer" in the bottom of the pots? A big differential in soil particle size (like when drainage layer is in contact with small substrate or when larger substrate is in contact with nursery soil) can actually cause the smaller substrate to retain water and inhibit proper drainage. I don't use drainage layers (though I do not have any large trees) because I have seen first hand that roots do not tend to grow in them.

I have done this on occasion and have seen the same effect you stated.

 

[Lazylightningny]

I bare root completely the first time around....it will either love the new substrate and reward me with vigorous growth, or die....or mope for a season then rebound.

Perhaps I need to get a little bolder with bare rooting, at least for deciduous and non-conifer evergreens.

 

[sorce]

But maybe I don't have a good grasp yet of what it depends on

Truth is ....

Everything has been bare rooted successfully by someone or another at some time....

Which means its not a death sentence in itself.

The "it depends" then are timing, health, timing, health, and timing and health.

Timing and amount for top pruning is also essential...

Where cutting off foliage during a waning moon, leaves energy and rebound lower than if cut during the waxing moon.

Over and over, though it may seem ok...these setbacks add up.
Improperly timed top cuts don't produce the neccesary roots to go with it.
I believe this is important to consider before and after repotting.

Sounds like not barerooting is more of a death sentence.

I would bare root everything during waning moons and see if your average doesn't change.

Sorce

 

[ysrgrathe]

That's not to say that I don't sometimes bare root. Plants that I do bare root tend to do well, but you can't just make a blanket statement to bare root all plants.

You can and should bare root all plants that are coming from nursery cans or field soil (at the appropriate time). Sawing a nursery soil root ball in half makes it drain worse, not better (due to perched water table). If you are nervous, half bare root: imagine a line dividing the pot in half horizontally, and then you remove ALL field soil from one side. This means that there is a vertical slice that is all new soil that all drains in the same way. I think you will find when you next repot that the bare rooted side has much better roots than the side you didn't touch!

As @sorce said -- you aren't doing this now, and it isn't working for you. I strongly suggest you follow what experts in the field do. (I don't claim to be one, but since I started following these practices my trees have grown much better).