Problematic over-potting

[Darold Petty]

Recently I had the good fortune to acquire a well-grown Laccospadix, suckering form.  I needed one more to complete my landscape design for a corner of my garden.  The plant came to me in a "15 gallon" pot.  Although full and well grown, it seemed to be in too large a pot.  Palms from Southern California growers are often sold this way,  leading to the joke that one is "purchasing a small plant, with a lot of very expensive potting soil!"

  let's compare pot sizes.  The 15-gallon is not truly a  15 gallon by liquid volume, and measures 14 inches diameter by 17 inches tall.  (36cmx43cm).

The pot I prefer is a Pro-Cal #7 Tall, measuring 11.5 inches diameter by 14 inches tall. (29cmx36cm)  So, the smaller pot has 80% of the height but only 56% of the volume. 

This is important because a small root system in a large pot volume will have difficulty utilizing all the retained moisture, and even worse, if the medium does get really dry then some areas will remain completely dry and become truly hydrophobic,  causing future irrigation to run through only the moist areas.

When I tipped the palm out of the 15 gallon pot this was the case, and the worst example I have encountered.  Some of the medium was saturated, and a large volume within the rootball was hydrophobic. It was so dry, that it just drained away from the roots like pouring dry sand out of a container.  I re-potted the palm into the smaller pot, using mostly the dry medium, as it was easier to pack around the roots and more certain to fill completely without voids.  Then, I had the problem of effective wetting, for this I like to soak the entire pot in a much larger container so that the water level is the full height of the smaller pot.  I leave it to soak for 24 hours.

  Here are some images, the saturated medium was mostly along one side of  the 15 gallon pot  and the bottom several inches. The hydrophobic medium was much lighter in color.

  Many growers feel that a larger pot volume with more room for root extension will produce faster growth, I don't agree.  The larger volume does reduce the frequency of irrigation labor.  I like the smaller volume, and more incremental increases in pot volume.  This will also allow addition of fresh medium more frequently, counteracting the leaching of nutrients by the irrigation.

  This has worked really well for me.  I have purchased palms so oversized that the pots had to be cut off.  This is not an issue, as the subsequent roots erupt higher above the older ones, so a solid mass of roots doesn't negatively effect future root growth.   I have 'down-sized' plants of Chamaedorea, Howea, Chamaerops, and now Laccospadix with no losses.   However, I would not attempt this with genera known to have more sensitive roots, such as Brahea or Bismarkia.   This can also be a helpful technique if one cannot dig such a large hole as the palm was potted upon acquisition.

Just to be compulsive, I will leave this palm in my greenhouse for a few months before ground planting  I did this downsize three days ago, and the spear on the main stem has already increased an inch (2.54cm).  

 

[Las Palmas Norte]

Nice rescue. This topic rarely is discussed and is every bit as important as the top growth. It can also be the problem when diagnosing plant issues. Palm health requires an understanding below the soil level as well as above. Conversely, I've purchased palms that were so crowed in undersized pots that there was very little soil remaining in the pot.

[happypalms]

The correct pot size with palms is critical to good health. I have observed with 70mm round tubes are better for seedlings than 70mm square tubes. Long deep tubes for certain remote germinating palms or the tiny 50mm square or round tubes all make a difference for tiny seedlings to large ones. Knowing your seedlings is the key. A overgrown root bound palm performs better than a loose fitting roots when potted up correctly. 70mm tubes won’t grow in a 200mm container. I pot a lot of palms up basically into the next size up. 140mm into 200mm provided there is a root ball. All too often I see overpotted palms suffer basically from lack of oxygen being to wet the roots sour and it’s game over for the palm. 

[meridannight]

My experience is different. Overpotting is not an issue as long as you have a well-draining medium and water the plant properly. Dry pockets that you mentioned will be an issue if you let them develop, and have to be avoided. 

I always go 2-3 ''pot sizes'' or even more up when transplanting. No problems ever with any plant. I've potted seedlings from 100mm (4 in) to 300mm (12 in) diameter straight up. I also am of the opinion that larger pot size will speed growth, however it's not initially visible. Given more space most plants will put most of their energy into developing a root system, and on top the plant seems to have stalled. Which is actually not the case and once the roots have filled up the plant will get a boost in growth on top of the soil.

Everyone has his preference on this topic, and I highly doubt there is one ''right'' way to go about this. This is more a cultural thing. The way a grower is used to caring for his plants (e.g. watering) will affect whether the overpotting strategy is viable for him or not. And that's perfectly fine. If you get better results by incremental sizing up, that's okay. It works in your case, so no need to change it. I do think overpotting is more difficult for most growers to master, so that is probably the reason you will see a lot of arguments against it. 

I overpot 80-90% of my plants (I can't overpot everything due to space constraints). And I swear by it. I have never had a single plant -- not palms, nor agaves, nor aloes, nor philodendra, or anything else -- develop an inch of root rot. Root rot doesn't exist in my world, and I'm not even sure how you can get it (technically I know how, I've just never observed it developing on my plants). 

 

[TropicsEnjoyer]

On 4/6/2025 at 6:25 PM, meridannight said:

Root rot doesn't exist in my world, and I'm not even sure how you can get it

You are both very skilled and a bit lucky. In my opinion it is the careless mistakes that lead to disaster more often than not. Water a cactus one day and forget it’s outside, it gets rain the next, and the day after is cloudy, and boom your roots are mush. 

[meridannight]

14 hours ago, TropicsEnjoyer said:

You are both very skilled and a bit lucky. In my opinion it is the careless mistakes that lead to disaster more often than not. Water a cactus one day and forget it’s outside, it gets rain the next, and the day after is cloudy, and boom your roots are mush. 

I guess I am a little lucky as well. It'll probably happen sooner or later, that I'll run into root rot, but the way things are that's the least of my concerns when growing plants right now.  

I just use an extremely well draining medium. I mix all the substrates I use myself, and they are specific to the species I'm growing. It is suitable for the way I water my plants (small amounts but often), and the result is that for most species the medium stays just moist but not wet (except for the species that do want wet feet, for example). It probably wouldn't work so well when used by a grower with vastly different regimen of watering. And, like I said, it's species-specific. I would run into trouble a lot more often if I just went with a generic mix-for-all. Substrate is one of the most important aspects -- if not the most important -- when growing plants in containers. It can make it or break it. 



 

[Darold Petty]

"Dry pockets that you mentioned will be an issue if you let them develop, and have to be avoided. "
How do you recognize and avoid this problem ?

[meridannight]

8 hours ago, Darold Petty said:

"Dry pockets that you mentioned will be an issue if you let them develop, and have to be avoided. "
How do you recognize and avoid this problem ?

At the end of the day it comes down to a chunky and airy potting mix that drains water very well, and watering the plants in a way that they never really dry out completely.

The potting mix on your images (where the palm is out of the pot) is not one I would say is airy enough and I wouldn't use it. It does seem to have perlite or pebbles or something in it, but not enough in proportion to soil. Most nurseries/sellers use mixes like that because soil amendments can be expensive, and so they often only use them in minimal amounts in order to save on their costs. It's something nurseries can do, but private growers can't afford to do with their plants, especially with expensive and/or rare specimens.
 

 

 

[Darold Petty]

Thanks, that is a clear and helpful explanation.   

[happypalms]

Palms and pots and the soil used is critical to good health in palms. From my experiences with growing container palms air is the most important thing followed by drainage both in combination together. Too much air and it’s a dry mix, then without good drainage it’s a heavy mix. Certain palms require both types of mix’s how do we know what mix for what palm only through knowledge of knowing the palms you wish to grow, then you can use that knowledge to grow other types of palms, learning all the way continuesly. Certainly different soil mediums come into play when mixing them together once again learning from past experiences. Gravel or other rock based minerals in a cold temperature like winter are not good for soil temperatures running colder than a warmer mix of soil, like a light mix with good drainage. That’s where good drainage comes into affect in winter hence being able to grow more tropical varieties in a cooler environment. Cost and availability plays a big key factor into the type of soil mix that is prepared. But  when it comes to rare  palms there is no price to put on it so the grower will obtain the best mix available for the best results. Having a basic knowledge amount on palms grows into a bigger amount of knowledge over time we all learn how to grow what we like. It’s a balance of organic matter for feeding the plant and air and water. I use four ingredients for my mixture of potting soil pelite, coco coir and organic matter of choice, I use high quality potting mix for organic matter and volcanic crushed rock powder for minerals. The percentage you use for each amount varies from mixture to mixture depending on how heavy or light you want your mix. My is about 65% coco coir 20%  organic matter 15% perlite give or take a few percentages. And I still learn something new every day about palms!