Root Trimming
Root Trimming
This past year I have been introduced to the concept of root trimming particularly when repotting. Apparently, the practice is standard procedure for Asian cactus growers and indeed is who I learned of it from. There's lots of good videos on youtube about it particularly of a Thai grower named Mr. Baso. Some of his videos even have English subs.
20 years ago, when I first started growing cacti, there's no way I'd ever trim roots and never even heard of the procedure. I've rather made an about face on that and began root trimming. So, far all I've done is Ariocarpus and Astrophytum. This week I'll be doing some trichocereus.
I've tried search CactiGuide for root trimming info and obviously people here know of the process and some practice it but there's not a lot of info about it. This is the best and most recent thread I've found regarding root trimming: viewtopic.php?t=47144&hilit=root+trimming
As I'm a recent convert, I'd like to start a discussion on root trimming as I know there's quite a wide variety of opinions and practices here. What I've learned of root trimming is that its best to do it near the end of winter dormancy when you do your repotting in preparation for spring. However, you can do root trimming at any time of year but not without consequences. Those consequences aren't necessarily anything negative deserving of fear and avoidance. It just means the cacti's growth may slow down for a bit while it redirects growth to the roots or such like. That's why its best to do near the end of winter dormancy. At least that's how I understand it.
Why would anyone trim roots? There are a lot of different reasons from what I've learned. The one reason that really got me to accept the practice is how it takes advantage of how and why plants grow feeder roots. Basically, as feeder roots deplete all the nutrients in their vicinity, they die off. The plant then extends new roots to seek out fresh nutrients to absorb. So, each time you trim the roots, you are basically resetting the the root system to grow new feeder roots. Remember, plants don't just absorb nutrients along their entire lengths; they only absorb nutrients through their feeder roots, and feeder roots are rather temporary. So, this is a cyclical process that plants do anyways. Root trimming makes the process more efficient particularly when done whilst repotting the plants before the plants revive from winter dormancy. I hope that makes sense. It was this understanding that really convinced me to adopt the practice. I had never really thought of how the plants' feeder roots will die off and regenerate. There's a lot of other reasons for root trimming such as prevention and treatment of root rot.
How does one go about root trimming? I find that understanding why root trimming ought to be done indicates a template for how to do it. And its simple but depends on the plant type. That is, does it have a tap root or not. Plants with tap roots such as lophophoras can have their roots trimmed down to the tap root. Plants without tap roots get their roots trimmed down to their primary roots. The primary roots are the thick ones coming out of the bottom of the cactus plant. Basically you are trimming off the feeder roots and secondary roots, leaving behind the primary roots. So, don't trim off the primary roots or tap root. Everything else can go. You'll need to be the judge of how short you trim the primary roots as that depends on plant size and the pot you intend on putting it in. Again, there are very good videos on youtube that demonstrate root trimming; a lot of the videos I saw involved astrophytum and lophophora.
Some growers will pot up their plants the same day as root trimming; some wait a couple days "for the roots to heal". I don't think it matters. Those who do go ahead and pot up their plants after root trimming do so with dry potting soil and wait a week or two before watering. The key is that you are potting the plant into dry soil. Either way, you wait a week or two before watering.
I hope this discussion helps de-mystify root trimming for people; I really hope I'm not just bonkers wrong about root trimming. Consider this an introduction to the practice as this is by no means exhaustive on the subject. Please share your thoughts and experiences. I'm sure many of you know a lot more about it than I do. I'd really like to hear about people's experience with root trimming on specific kinds of plants, how you do it and why. For example: I really wasn't sure what to do with my ariocarpus. Sure it has a big tap root, but the primary roots were rather thin and delicate. I wasn't sure if I should trim down to the tap roots or only trim down to the primary roots. I chose the safe route and trimmed down to the primary roots. I'm just a beginner after all.
BTW: I found toe-nail clippers like this to do an excellent job of trimming roots: https://www.walmart.com/ip/Easy-Grip-To ... /437959691
20 years ago, when I first started growing cacti, there's no way I'd ever trim roots and never even heard of the procedure. I've rather made an about face on that and began root trimming. So, far all I've done is Ariocarpus and Astrophytum. This week I'll be doing some trichocereus.
I've tried search CactiGuide for root trimming info and obviously people here know of the process and some practice it but there's not a lot of info about it. This is the best and most recent thread I've found regarding root trimming: viewtopic.php?t=47144&hilit=root+trimming
As I'm a recent convert, I'd like to start a discussion on root trimming as I know there's quite a wide variety of opinions and practices here. What I've learned of root trimming is that its best to do it near the end of winter dormancy when you do your repotting in preparation for spring. However, you can do root trimming at any time of year but not without consequences. Those consequences aren't necessarily anything negative deserving of fear and avoidance. It just means the cacti's growth may slow down for a bit while it redirects growth to the roots or such like. That's why its best to do near the end of winter dormancy. At least that's how I understand it.
Why would anyone trim roots? There are a lot of different reasons from what I've learned. The one reason that really got me to accept the practice is how it takes advantage of how and why plants grow feeder roots. Basically, as feeder roots deplete all the nutrients in their vicinity, they die off. The plant then extends new roots to seek out fresh nutrients to absorb. So, each time you trim the roots, you are basically resetting the the root system to grow new feeder roots. Remember, plants don't just absorb nutrients along their entire lengths; they only absorb nutrients through their feeder roots, and feeder roots are rather temporary. So, this is a cyclical process that plants do anyways. Root trimming makes the process more efficient particularly when done whilst repotting the plants before the plants revive from winter dormancy. I hope that makes sense. It was this understanding that really convinced me to adopt the practice. I had never really thought of how the plants' feeder roots will die off and regenerate. There's a lot of other reasons for root trimming such as prevention and treatment of root rot.
How does one go about root trimming? I find that understanding why root trimming ought to be done indicates a template for how to do it. And its simple but depends on the plant type. That is, does it have a tap root or not. Plants with tap roots such as lophophoras can have their roots trimmed down to the tap root. Plants without tap roots get their roots trimmed down to their primary roots. The primary roots are the thick ones coming out of the bottom of the cactus plant. Basically you are trimming off the feeder roots and secondary roots, leaving behind the primary roots. So, don't trim off the primary roots or tap root. Everything else can go. You'll need to be the judge of how short you trim the primary roots as that depends on plant size and the pot you intend on putting it in. Again, there are very good videos on youtube that demonstrate root trimming; a lot of the videos I saw involved astrophytum and lophophora.
Some growers will pot up their plants the same day as root trimming; some wait a couple days "for the roots to heal". I don't think it matters. Those who do go ahead and pot up their plants after root trimming do so with dry potting soil and wait a week or two before watering. The key is that you are potting the plant into dry soil. Either way, you wait a week or two before watering.
I hope this discussion helps de-mystify root trimming for people; I really hope I'm not just bonkers wrong about root trimming. Consider this an introduction to the practice as this is by no means exhaustive on the subject. Please share your thoughts and experiences. I'm sure many of you know a lot more about it than I do. I'd really like to hear about people's experience with root trimming on specific kinds of plants, how you do it and why. For example: I really wasn't sure what to do with my ariocarpus. Sure it has a big tap root, but the primary roots were rather thin and delicate. I wasn't sure if I should trim down to the tap roots or only trim down to the primary roots. I chose the safe route and trimmed down to the primary roots. I'm just a beginner after all.
BTW: I found toe-nail clippers like this to do an excellent job of trimming roots: https://www.walmart.com/ip/Easy-Grip-To ... /437959691
- Steve Johnson
- Posts: 4766
- Joined: Thu Nov 03, 2011 4:44 am
- Location: Los Angeles, CA (Zone 10b)
Re: Root Trimming
Interesting and important topic, so here's an item for your consideration:
https://succulentalley.com/cactus-root-systems/
While the article is a good introduction to different types of cactus root systems, I'll point out a couple of problems with it. For example...
There are some cacti in my collection that need to have their roots trimmed. Not sure when I'll be able to do it, although I wouldn't in the summer heat of August and September. Not in the dead of winter either (emphasis on the word "dead"), but the fall here in SoCal isn't a bad time since the cacti are dormant and they're starting their fall-winter dry spell as there are plenty of warm (sometimes hot days) in October and November.
My approach is to trim the roots back just enough to leave a margin of about 3/4" between the root ends and the sides and bottom of the pot. If it would mean cutting into a tap root, no way -- I'll need a deeper pot. I don't see anything wrong with trimming the lower part of a primary root, but some good judgment is required there (better if we can avoid it). If the diameter of the above-ground part of the base exceeds the diameter of the pot, you'll need a wider pot. (A few such cacti are in my collection -- a problem, but it's a nice problem to have!) With that said, some cactus species enjoy being crowded in their pots -- I have a few of those cacti too.
https://succulentalley.com/cactus-root-systems/
While the article is a good introduction to different types of cactus root systems, I'll point out a couple of problems with it. For example...
- "If you want your cacti to grow to their full size, it is recommended to use deep and wide pots that can accommodate their extensive root systems."
- "Hair roots on cacti have a short lifespan, usually lasting only a few hours or days. Fine roots also have a limited time before they shed in dry conditions and regrow if needed. Cutting into this natural root cycle should only be considered as a last resort and requires careful consideration."
There are some cacti in my collection that need to have their roots trimmed. Not sure when I'll be able to do it, although I wouldn't in the summer heat of August and September. Not in the dead of winter either (emphasis on the word "dead"), but the fall here in SoCal isn't a bad time since the cacti are dormant and they're starting their fall-winter dry spell as there are plenty of warm (sometimes hot days) in October and November.
My approach is to trim the roots back just enough to leave a margin of about 3/4" between the root ends and the sides and bottom of the pot. If it would mean cutting into a tap root, no way -- I'll need a deeper pot. I don't see anything wrong with trimming the lower part of a primary root, but some good judgment is required there (better if we can avoid it). If the diameter of the above-ground part of the base exceeds the diameter of the pot, you'll need a wider pot. (A few such cacti are in my collection -- a problem, but it's a nice problem to have!) With that said, some cactus species enjoy being crowded in their pots -- I have a few of those cacti too.
If you just want photos without all the blather, please visit my Flickr gallery.
My location: Los Angeles, CA (Zone 10b)
My location: Los Angeles, CA (Zone 10b)
- greenknight
- Posts: 4878
- Joined: Tue Apr 30, 2013 4:18 am
- Location: SW Washington State zone 8b
Re: Root Trimming
I usually lose enough roots in the repotting process that no further root pruning is called for. If there are any roots left that are too long for the pot then I trim them as Steve describes - you don't want the roots to be wadded up.
Spence
Re: Root Trimming
greenknight wrote: ↑Tue Jun 04, 2024 5:51 am I usually lose enough roots in the repotting process that no further root pruning is called for. If there are any roots left that are too long for the pot then I trim them as Steve describes - you don't want the roots to be wadded up.
I do exactly the same thing.
I've read that Astrophytum hybrid growers prefer to cut off fleshy taproots from A. asterias cultivars after which the plants will regrow fibrous roots that are less susceptible to rot, and therefore can be watered more often.
Re: Root Trimming
There are exceptions however. On my experience Uebelmannia and Discocactus do not like their roots touched.
Re: Root Trimming
Yes very simplistic. It really doesn't take into account of cacti with long tap roots. I use tall, narrow pots for those.Steve Johnson wrote: ↑Tue Jun 04, 2024 5:27 am Interesting and important topic, so here's an item for your consideration:
https://succulentalley.com/cactus-root-systems/
While the article is a good introduction to different types of cactus root systems, I'll point out a couple of problems with it. For example...That's a simplistic statement. "Deep" and "wide" are relative terms anyway, so IMO not all that useful.
- "If you want your cacti to grow to their full size, it is recommended to use deep and wide pots that can accommodate their extensive root systems."
Its like they are trying to contradict themselves. This is another example where two humans can take the exact same data and come to completely opposite conclusions. Oh the humanity...Steve Johnson wrote: ↑Tue Jun 04, 2024 5:27 am
- "Hair roots on cacti have a short lifespan, usually lasting only a few hours or days. Fine roots also have a limited time before they shed in dry conditions and regrow if needed. Cutting into this natural root cycle should only be considered as a last resort and requires careful consideration."
This sloughing off of root hairs is what I've heard others say is why root trimming is a good idea. It gets all that dead material out of the pot. So, you trim the roots down to the primary roots which manually helps the plant to get rid of its dead parts so that they aren't left decomposing in the pot and potentially contributing to root rot. This is one way in which root trimming is a preventative measure. Same data; opposite conclusions.
That's good to know. Thank you. Learning about root trimming has been a game changer for me. But as nikoledm indicates above, root trimming may not be appropriate for all cacti. That's why I'm asking people to share their experience. If there are cacti that they believe root trimming is not appropriate, I'd like more information. Which plants those are and what led them to their conclusion. We need to know what happened and anything else relevant.Steve Johnson wrote: ↑Tue Jun 04, 2024 5:27 am AirWreck, everything you said is generally sound and it busts the myth.
You make a good point that I hadn't thought of: trimming roots as the plants are going into winter dormancy, assuming that is indeed the point you are making here. And it does make sense to me as it seems it would take advantage of the plant being in relative active growth albeit winding down in preparation for winter dormancy and so ought to be able to heal up its roots prior to entering winter dormancy. Can anyone else confirm that it really works like this? Because there's a chance that trimming the roots prior to dormancy may deny the plant the nutrients it has in its roots to use during dormancy; but I guess how exactly you trim the roots would matter. Otoh, trimming roots prior to dormancy would remove infected roots from being able to do in the plant during dormancy. What do I know? So many variables to consider.Steve Johnson wrote: ↑Tue Jun 04, 2024 5:27 am There are some cacti in my collection that need to have their roots trimmed. Not sure when I'll be able to do it, although I wouldn't in the summer heat of August and September. Not in the dead of winter either (emphasis on the word "dead"), but the fall here in SoCal isn't a bad time since the cacti are dormant and they're starting their fall-winter dry spell as there are plenty of warm (sometimes hot days) in October and November.
We all want to be sure about things before doing irreversible procedures with our plants and I know that's why so many people are hesitant to attempt root trimming. Like Mr. Baso said in one of his videos on root trimming, essentially, "you can trim roots at any time but not without consequences. You have to be sure that the consequences are acceptable to you." Well, learning what these consequences might be as well as the why's and how to's is why I wanted to initiate this conversation. Sometimes, these consequences may be small potatoes, other times not.
- Steve Johnson
- Posts: 4766
- Joined: Thu Nov 03, 2011 4:44 am
- Location: Los Angeles, CA (Zone 10b)
Re: Root Trimming
Let's not forget about fall...
Cactus dormancy isn't like an on-off switch, so transitioning into and out of it takes some time. Many hobbyists look at daytime highs instead of overnight lows to determine the transitions, but it's the overnights that tell the real story. Rule of thumb -- when overnight lows are consistently below 50 in the fall, cacti are beginning their dormant period. Here in SoCal, they may not be fully dormant in October, but they are in November. If I do any root-trimming in fall, November is probably the best time -- the idea here is that they'll sleep through any "transplant shock" that might be a problem if I did it in summer. When overnight lows ramp up and start fluctuating between the upper 40s and low 50s, the cacti are transitioning out of dormancy as their roots slowly wake up. Depending on the year in my part of LA, it could be late February, March or early April. When the overnight lows are consistently above the lows 50s, they're fully awake. If I miss the opportunity for some root-trimming in November, I'll wait until spring. By the way -- some people might get freaked out by the term "transplant shock", but it sounds worse than it really is.
As nikoledm said, there are exceptions to the general rule that cactus roots can be trimmed. Uebelmannia and Discocatus were mentioned, so I'd put Melocactus on that list too. (I'm talking only about root-trimming -- while I can't speak re. Uebelmannia, the idea that Discocactus and Melocactus won't tolerate repotting is a myth. If you don't believe me, see this: https://www.cactiguide.com/forum/viewtopic.php?t=33959.) Another exception -- don't trim the roots of old cacti. "Old" is a relative term, but if we know the average lifespans of the species we're growing, we'll know when our cacti are getting too old to take a chance on trimming their roots.
If you just want photos without all the blather, please visit my Flickr gallery.
My location: Los Angeles, CA (Zone 10b)
My location: Los Angeles, CA (Zone 10b)
Re: Root Trimming
The trimming of cacti roots was a common practice in the country where I was borne.
The basic rule was as follows:
1. Cut tap roots of asterias
2. Do not cut tap roots of Aricarpus species
1. Asterias grow slowly but it will be changed to a reasnable speed if you fed water well in hot summer but this practice will be a cause of tap roots rotting. If the asterias do not have tap roots, the roots rotting problem will be minimized.
I cut tap roots of 2 years old seedlings and rerooting. Tap roots will never regrow, fine roots only.
Cut roots every year in Feburary and set for rerooting of young asterias in March in Tokyo. The rooting medium is akadama in there. I also cut tap roots of other Astrophytum species such as myriostigma.
2. The rule was do not cut tap roots of Ariocarpus because tap roots would never regrow but I found recently they cut tap roots of ariocarpus also. They said I should start to cut tap roots when seedlings were 3 years old.
The small scale of test is under going but it seems working well.
I understand our members live in different places and I am not sure this practice work in your place or not.
The basic rule was as follows:
1. Cut tap roots of asterias
2. Do not cut tap roots of Aricarpus species
1. Asterias grow slowly but it will be changed to a reasnable speed if you fed water well in hot summer but this practice will be a cause of tap roots rotting. If the asterias do not have tap roots, the roots rotting problem will be minimized.
I cut tap roots of 2 years old seedlings and rerooting. Tap roots will never regrow, fine roots only.
Cut roots every year in Feburary and set for rerooting of young asterias in March in Tokyo. The rooting medium is akadama in there. I also cut tap roots of other Astrophytum species such as myriostigma.
2. The rule was do not cut tap roots of Ariocarpus because tap roots would never regrow but I found recently they cut tap roots of ariocarpus also. They said I should start to cut tap roots when seedlings were 3 years old.
The small scale of test is under going but it seems working well.
I understand our members live in different places and I am not sure this practice work in your place or not.
My favorite cacti photos are in Flickr https://www.flickr.com/photos/146109677@N06/albums/
Re: Root Trimming
Steve, again thanks for sharing that link about cactus roots. I realize I've been calling napiform roots as tap roots when technically the two are different forms of roots. That webpage doesn't seem to say "don't cut napiform roots'; however, I wouldn't recommend it. Sometimes though it is necessary when rot has extended up into it. But I've seen some Thai growers really shave down the napiform roots of lophophoras and some ariocarpus (A. kotschoubeyanus mostly) when repotting.
Re: Root Trimming
Update: Before I had originally posted this thread, I had trimmed the roots of an A. myriostigma. Well, that plant is doing well and has already presented some very good growth. So, this gives you some idea of a time frame between repotting/root trimming and signs of new growth: 2 months. Nice huh?
I wish I had taken pictures of how I trimmed the roots but, really, there's some very good videos on youtube regarding root trimming. I suggest watching those.
I wish I had taken pictures of how I trimmed the roots but, really, there's some very good videos on youtube regarding root trimming. I suggest watching those.
- jerrytheplater
- Posts: 1253
- Joined: Mon Mar 22, 2021 7:38 pm
- Location: Bloomingdale, NJ (USDA Zone 6b)
- Contact:
Re: Root Trimming
I posted a video of an Indonesian grower of Malagasy Euphorbia repotting his mother plants and doing massive root pruning back on Dec 26, 2022. viewtopic.php?t=47560 . Still a good one to watch.
Jerry Smith
Bloomingdale, NJ
45 inches (114 cm) rain equivalent per year, approx. evenly spread per month
2012 USDA Hardiness Zone 6b: -5F to OF (-20C to -18C) min.
Bloomingdale, NJ
45 inches (114 cm) rain equivalent per year, approx. evenly spread per month
2012 USDA Hardiness Zone 6b: -5F to OF (-20C to -18C) min.
Re: Root Trimming
Yeah, it can be surprising to see how far back they will prune. When I was first watching these videos, I'd be saying "wait you're not done yet and you're cutting even more off? At what point do you stop cutting?" After having done it myself now, I'm a convert.
Here's one link to a video of Mr. Baso doing root trimming on a Lophophora: https://www.youtube.com/watch?v=A3bSrZi8V0U
He has more videos. Some include English subs. All are worth watching. This guy grows some incredible plants, mostly ariocarpus and lophophoras.
Here's one link to a video of Mr. Baso doing root trimming on a Lophophora: https://www.youtube.com/watch?v=A3bSrZi8V0U
He has more videos. Some include English subs. All are worth watching. This guy grows some incredible plants, mostly ariocarpus and lophophoras.
Re: Root Trimming
I've inadvertently done a side by side experiment. Last spring, I was in the process of repotting two window boxes of cacti when I was learning about root trimming. Each box had about a dozen cacti: mostly L. decipiens (Mesa Garden seed) and A. agavoides. One box I repotted before I learned about root trimming and so those plants did not have their roots trimmed. The other box was repotted after learning about root trimming and did have their roots trimmed. Both boxes are about the same size and depth. They were both given the same soil, under the same light, watered same days. Really identical care; side by side. The only difference was one was root trimmed. The non-root trimmed plants started growing sooner and faster than the root trimmed ones. However, last month the roots of the non-root trimmed plants began to rot whilst the root trimmed plants are growing very nicely. Last weekend, I dug up all the plants with rotting roots and am letting them dry out and heal before I trim their roots and repot them. I'm also going to put them in a shallower pot as their roots were never very deep.
I wasn't really sure at first if the plants were presenting root rot or if there was a bug infestation causing them to become soft as I was finding what appears to be thrips on the plants that were not root trimmed. I suspect the thrips were attracted to the non-root trimmed plants because they could smell the rot. I have yet to find thrips on the root trimmed plants but I dusted them with diatomaceous earth anyway.
I'm definitely a firm believer in root trimming.
I wasn't really sure at first if the plants were presenting root rot or if there was a bug infestation causing them to become soft as I was finding what appears to be thrips on the plants that were not root trimmed. I suspect the thrips were attracted to the non-root trimmed plants because they could smell the rot. I have yet to find thrips on the root trimmed plants but I dusted them with diatomaceous earth anyway.
I'm definitely a firm believer in root trimming.
- Steve Johnson
- Posts: 4766
- Joined: Thu Nov 03, 2011 4:44 am
- Location: Los Angeles, CA (Zone 10b)
Re: Root Trimming
I didn't realize how important occasional root-trimming is, but man, I see what happens when cacti stay rootbound too long. In fact it's now obvious that I have a bunch that are way overdue, so I have my work cut out for me.
If you just want photos without all the blather, please visit my Flickr gallery.
My location: Los Angeles, CA (Zone 10b)
My location: Los Angeles, CA (Zone 10b)
Re: Root Trimming
I just finished trimming the roots on all these plants. There wasn't a lot of actual cutting to do. Most of the feeder roots dried up to a crisp and just crumbled away when I brushed them with a small paint brush. The feeder roots that didn't present rot did not dry up and crumble; there were few of these. The napiform root, what I call the tap root, remained healthy on all the plants; so I suppose I uprooted them all in time. These plants may need a year or two to grow a new set of roots and resume growing but they ought to be better off for it considering how well the root trimmed plants are doing since having their roots trimmed last spring.
During all this, I found continued evidence of rust fungus on the tap root of a couple of the plants. I've been fighting this nemesis for 20 years since my plants were infected by a pine tree that over-hung the patio of an apartment that I was renting. So, I'm sure that this episode of root rot was not 100% because of the soil and how I was watering them and all that. They really needed those old infected roots to be trimmed away and I didn't do that last spring. Well, its done now and there are fresh new roots to come next year. I'm also going to be putting them in a shallower pot. These plants weren't putting their roots down as deeply as I assumed they would. And I'll see if I can provide pictures. I have technology challenges with that; so no promises.
During all this, I found continued evidence of rust fungus on the tap root of a couple of the plants. I've been fighting this nemesis for 20 years since my plants were infected by a pine tree that over-hung the patio of an apartment that I was renting. So, I'm sure that this episode of root rot was not 100% because of the soil and how I was watering them and all that. They really needed those old infected roots to be trimmed away and I didn't do that last spring. Well, its done now and there are fresh new roots to come next year. I'm also going to be putting them in a shallower pot. These plants weren't putting their roots down as deeply as I assumed they would. And I'll see if I can provide pictures. I have technology challenges with that; so no promises.