Root behavior in porous vs. nonporous pots

Discuss repotting, soil, lighting, fertilizing, watering, etc. in this category.
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One Windowsill
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Re: Root behavior in porous vs. nonporous pots

Post by One Windowsill »

Surely silver is more appropriate for the South West Native American cultures?

I am convinced square pots are best for the roots.
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Steve Johnson
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Re: Root behavior in porous vs. nonporous pots

Post by Steve Johnson »

Hi Steve-0,

Before you commit to the designs of the pottery you'll take the time and effort to execute, there's something you'll need to be aware of...

Cacti growing in the ground have a free run of the roots, but cacti in pots do not. Since the pots act as a barrier to the drainage that would take place in open ground, what we need is free drainage of a mix that also provides enough water for the growth of our plants. Assuming that we have the right mix, there's something we need to avoid -- overpotting, defined as a soil mass in the pot which exceeds the ability of the roots to take up water as the mix dries out. Think of this as a "wicking" effect, and overpotted cacti lose their roots because they can't "wick up" most or all of the water being retained in the mix. If you size the pot properly to the plant, overpotting won't be a problem. The sizing "rule of thumb" is a margin of 1/2"-3/4" around the diameter of the root ball or base of the plant (whichever is widest), and 1/2"-3/4" below the longest root. Here are a few examples:

Cactus A has a root ball diameter of 2", and the diameter of the stem's base is 3". The inside diameter at the top of the pot should be no more than 4 1/2". Cactus B has a root ball diameter of 4", and the diameter of the stem's base is 3 1/2". The inside diameter at the top of the pot should be no more than 5 1/2". You can make the pot as thick as you want, so outside diameter isn't important. Cactus C has a length of 2 1/4" going from the stem's "soil line" to the tip of the longest root. The inside depth should be no more than 3", although you can increase that to make room for gravel top dressing if you so desire. We don't need to be overly precise about sizing, but some common-sense judgment is required -- putting a tiny cactus into a big pot makes no sense. IMO there's nothing wrong with underpotting a little bit.

Cactus A might be overpotted in a cylindrical pot, but it'll be fine in a tapered pot similar to the glazed ceramic pot you saw in my first post. Cactus B's roots might get jammed in with a tapered pot, but a cylindrical pot would be perfect. Now, my friend, I have some good news and bad news for you. First, the bad news:

Image
Image

Both of these pot designs are completely unsuitable for growing cacti because your mix would contain too much soil mass. The good news is that you can custom-make cylindrical and/or tapered pots to accommodate the roots of your cacti. The pots need to be functional first, and it would be helpful if you can see your cacti in their bare-root state as you determine the correct inside diameters and depths of pots you'll be making. If your plants grow well over time and need bigger pots, you're set! Here's something else that may be helpful...

A few years ago, I went to Desert Creations in Northridge CA, and asked their potter-in-residence about making a few glazed ceramic pots for me. Unfortunately he left DC before I had a chance to place the order, but he told me that ceramic shrinks about 20% in the firing process. Keep that in mind as you make pots in the sizes you need -- I'd hate to have you go to all that trouble and find out your pots are too small!
If you just want photos without all the blather, please visit my Flickr gallery.
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Jangaudi
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Re: Root behavior in porous vs. nonporous pots

Post by Jangaudi »

Agree with everything here, but I do find some larger and special pots attractive, and I guess one could counteract the overpotting issue by adding some large rocks on the side ? Or alternatively just sink your pot into a pebble filled larger pot.
DaveW
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Re: Root behavior in porous vs. nonporous pots

Post by DaveW »

Alternatively just stick the plant in a regular plastic pot inside your fancy glazed one. :D Hope your fancy pot also has a drainage hole?

Always remember the plant is the most important thing and its needs, the pot is merely its container. Once the fancy pot becomes more important than what it contains the plant will probably suffer.

Unlike in the UK, in the US the container is often worth more than the plant it contains and is aimed to influence the judge who should be judging the plant and not the value of the container. A fancy pot or container should not influence the judge anymore than if it was in a basic clay or plastic pot.
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Steve-0
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Re: Root behavior in porous vs. nonporous pots

Post by Steve-0 »

Thanks, guys for the replies and advice.

As per my earlier post with the Southwest pot image = Something like this with the shape adjusted to be more suited for plants. ie - wider neck, drain holes, flat bottom, glazed insides for waterproofing.

This particular image was shown for the design...not as a shape to put a cactus into. Sorry if it was misinterpreted that I plan to shove cacti down into the necks of this shape pots. But with a plastic pot containing the soil mix and cactus pretty much anything would work...even a cowboy boot. Not mine but I Just had to throw that out there. Obviously, the boot pot needs a drain hole... which may be there unseen.

And don't even Google "Cactus in a Cowboy boot"....there's a ton of them. lol...
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boot pot.jpg
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Steve-0
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Re: Root behavior in porous vs. nonporous pots

Post by Steve-0 »

These are samples of store thrift bought practice pots...lots of plain janes out there needing a little dressing up. Those little 3 inch squares of plastic jammed side by side with cactus don't do much for me...Different strokes. Looks too Walmart or even Altman Plants, Big Box store plant trays to me. I get it... when there a lack of space in one's home or greenhouse and also in the mass production green houses. I'm kind of an artsy, eclectic person.

Sorry, Steve J if this side track into pots is derailing your VERY informative thread.
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Whitewashed clay pot orig. SW style design added with terracotta red wash.
Whitewashed clay pot orig. SW style design added with terracotta red wash.
IMG_20210110_165736612.jpg (96.31 KiB) Viewed 12623 times
Bisque fired Orchid pot. Drilled drain holes, SW style black on white design added.
Bisque fired Orchid pot. Drilled drain holes, SW style black on white design added.
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Thrift store purchase...personalized.
Thrift store purchase...personalized.
POT3.jpg (50.48 KiB) Viewed 12623 times
Easter edible arrangement pot - thrift store. And after.
Easter edible arrangement pot - thrift store. And after.
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Shane
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Re: Root behavior in porous vs. nonporous pots

Post by Shane »

Wow, lots of interesting stuff in this thread!
One Windowsill wrote: Tue Jan 12, 2021 12:08 am Perhaps you should look into an external glaze with a high infra-red reflectance to keep the roots cool
[...]
Complex inorganic green pigments having a high near infrared solar reflectance have been synthesized[...]
Interestingly, clothing dye is pretty NIR reflective too, even dark colors like black (or dark green). I had a NIR camera I used to play around with. I doubt cloth dye would do well at kiln temperatures though...
DaveW wrote: Mon Jan 11, 2021 11:21 am I don't know about the USA, but in the colder UK many clay or terracotta pots are now sold as frost proof. The old clay pots if left out in winter used to laminate or shale since the water in the pot walls froze and expanded, thus ruining the pot. Modern terracotta pots here therefore are now fired at much higher temperatures and are therefore as non porous as ceramic or plastic ones
At least in the US (IMO), high fired pots exist but are still less common than the porous low fired variety. I have a collection of terra cotta pots I found in alleys and the like and before I plant anything in them I splash some water on them to check the porosity. There's a range of porosity, but most are fairly porous. I'm not sure what I'm going to do with all the porous ones, they're pretty much worthless. I've shellacked some of them but it's more work than I'd really like to do
One Windowsill wrote: Tue Jan 12, 2021 5:48 pm I am convinced square pots are best for the roots.
I am intrigued. What leads you to believe this? (side note: I'm transitioning to square pots to save space)

For me, it's hard to imagine what this hobby was like in the old days before plastic pots. They're abundant, durable, nonporous, lightweight and dirt cheap. They're the perfect pot. Pots are something I really don't have to think about ever, and I'm grateful for that. I do get some people like pots, and there's nothing wrong with that as a hobby either. But only the plants are my hobby

I have a funny story about pots actually. At a meeting of my local CSS, an older member explained that some people think that a plant's flowers shouldn't effect a judge's evaluation of a plant in a show, since "It's a plant show not a flower show". I wonder what "some people" would think of all those fancy pots people show their plants in
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Fishhook cacti are like cats, they only like to be petted in one direction
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Steve Johnson
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Re: Root behavior in porous vs. nonporous pots

Post by Steve Johnson »

Steve-0 wrote: Wed Jan 13, 2021 4:54 pmSorry, Steve J if this side track into pots is derailing your VERY informative thread.
No worries, Steve-0, and I like what you're doing with those thrift store pots! I've seen too many mass-produced terracotta pots over the years, and they're boring. Plastic pots look cheap, and not exactly durable with constant UV exposure outside. Once I made the move to glazed ceramic, my aesthetic sense led me to select pots that compliment the plant. Such being the case, I think DaveW might appreciate the following comment...

I have absolutely zero interest in exhibiting my cacti at shows, and I could never understand why judges factor the pots into the points system they use for the cacti and succulents they're judging. How many time I've heard this -- "nice plant, but the pot is beautiful!" If the plants are upstaged by the pots, IMO it's a pretty badly misplaced sense of priority. Not sure how prevalent this is at US shows in general, but based on the ones I've been to here in the greater Los Angeles area, the pots seem to be way too important in the overall presentation. If you have good taste (and I think you do), you'll choose your pots well with the understanding that your cacti are the priority as you stage the show you get to see every day.
If you just want photos without all the blather, please visit my Flickr gallery.
My location: Los Angeles, CA (Zone 10b)
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Steve-0
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Re: Root behavior in porous vs. nonporous pots

Post by Steve-0 »

Steve, my sentiments exactly. Here's one of my Christmas cactus purchases from Miles @ Mile2Go...in a new home.
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Ferocactus wislizeni from Miles2Go
Ferocactus wislizeni from Miles2Go
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Shane
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Re: Root behavior in porous vs. nonporous pots

Post by Shane »

Steve-0 wrote: Thu Jan 14, 2021 3:48 pm Here's one of my Christmas cactus purchases from Miles @ Mile2Go...in a new home.
Are those shark vertebrae on your bracelet?
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One Windowsill
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Re: Root behavior in porous vs. nonporous pots

Post by One Windowsill »

Shane wrote: Thu Jan 14, 2021 2:28 am
One Windowsill wrote: Tue Jan 12, 2021 5:48 pm I am convinced square pots are best for the roots.
I am intrigued. What leads you to believe this? (side note: I'm transitioning to square pots to save space)
Whenever I repot plants from round pots there is usually a thick circle of roots at the bottom of the pot that just go round and round. In square pots they tend to go in different directions when they hit the corner so many go back into the body of the soil. Even if they are a mass, they seem to be less packed together.
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Steve-0
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Re: Root behavior in porous vs. nonporous pots

Post by Steve-0 »

Shane wrote: Thu Jan 14, 2021 4:31 pm
Steve-0 wrote: Thu Jan 14, 2021 3:48 pm Here's one of my Christmas cactus purchases from Miles @ Mile2Go...in a new home.
Are those shark vertebrae on your bracelet?
Hey Shane, they're actually Alaskan Salmon vertebrae....but good eye. These came out of the South end of a North bound bear on Prince of Wales Island, Alaska. I fish there annually for the past 21 years and can answer that question in the affirmative that bears do indeed poop in the woods. And NO! I did not dig through bear scat to retrieve these bones.

The bear caught and ate the Salmon, pooped out the non digestible bones ( the vertebrae ) just as you see them. The ribs were dissolved off of the discs. Anyway...being in a temperate rain forest with 12 feet of precip annually... the rain washed away the poo and left the bones in a nice group minus the poop. I took a quick break from fishing and looked down to see and collect these bones. They already had a hole through them to string on the bracelet.

The jade beads come from the Cassiar mine in British Columbia, Canada.
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Alaska Salmon vertebrae and BC jade mala.
Alaska Salmon vertebrae and BC jade mala.
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Shane
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Re: Root behavior in porous vs. nonporous pots

Post by Shane »

One Windowsill wrote: Thu Jan 14, 2021 6:11 pm Whenever I repot plants from round pots there is usually a thick circle of roots at the bottom of the pot that just go round and round. In square pots they tend to go in different directions when they hit the corner so many go back into the body of the soil. Even if they are a mass, they seem to be less packed together.
Hmm very interesting. Think you're onto something here. What's your experience with Square pots with rounded corners?

I'd like to learn more about this and think I'll do an experiment. I'll plant a bunch of uprooted Aloe cuttings in different pots then later dig them up and see how the roots look. I'm choosing Aloe because they get root bound easily (seems like the roots take like 2 laps around the pot then head straight out of the bottom ](*,) ), and because people give away lots of Aloe they trimmed back in their yard at my local CSS (so I can get lots of cuttings of the same plant). (Note that in person meetings are suspended indefinitely so I probably won't be able to do this for a while)
Los Angeles, California (USA)
Zone 10b (yearly minimum temperature 1-5° C)

Fishhook cacti are like cats, they only like to be petted in one direction
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Shane
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Re: Root behavior in porous vs. nonporous pots

Post by Shane »

Steve-0 wrote: Thu Jan 14, 2021 8:07 pm Hey Shane, they're actually Alaskan Salmon vertebrae....but good eye. These came out of the South end of a North bound bear on Prince of Wales Island, Alaska. I fish there annually for the past 21 years and can answer that question in the affirmative that bears do indeed poop in the woods. And NO! I did not dig through bear scat to retrieve these bones.

The bear caught and ate the Salmon, pooped out the non digestible bones ( the vertebrae ) just as you see them. The ribs were dissolved off of the discs. Anyway...being in a temperate rain forest with 12 feet of precip annually... the rain washed away the poo and left the bones in a nice group minus the poop. I took a quick break from fishing and looked down to see and collect these bones. They already had a hole through them to string on the bracelet.

The jade beads come from the Cassiar mine in British Columbia, Canada.
That's pretty cool. I used to find fossil shark vertebrae sometimes when I lived on the east coast. I suppose salmon verts are bony rather than cartilagous so they'd be better than (non-fossilized) shark bones for a bracelet anyway
Los Angeles, California (USA)
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Fishhook cacti are like cats, they only like to be petted in one direction
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Re: Root behavior in porous vs. nonporous pots

Post by mikethecactusguy »

Hi Steve
This topic has now proven itself correct. I have a tendency to use reclaimed terra pots that used to house store bought Orchids. Over the weekend I had noticed a plant leaning and decided to check it. When I unpotted it, the roots were stuck to the side of the pot and the soil was drying from the center out. This was one of these recycled cabo shaped orchid pots. I tested it and found it very porous. I'm guessing it was a cheap low fire pot.
This is the first time I have had this happen. I guess I need to check all the "cabo" pots to make sure I am not having the same issue.
Mike M
Mike The Cactus Guy
Enjoying the Spines
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