PET Potting Method

[isurus79]

Originally Posted by Subrosa

Pretty much a combination of semi-hydroponic culture and the layered substrate method.

Exactly!

Originally Posted by Subrosa

I can't see the purpose of EcoWeb cubes on the bottom though. I use stone for ballast, but as far drainage, aeration, or anything like that I don't see a need. By the time the roots of a Catasetinae get that long, they'd grow in a port a potty!

I think as long as the media at the bottom doesn't break down, that's all that matters. Having bark or something else down there would eventually turn to mush, but then again this group may like that! None of the Brazilians I've seen or spoken with have used a compostable media at the bottom, so I followed suite. Could be an interesting experiment though.

---------- Post added at 12:09 PM ---------- Previous post was at 11:58 AM ----------

Originally Posted by Ray

Nice work, Steve, and nice to put a face on an online contact.

Thanks! Ray, I bet you'd have a lot to add with a YouTube channel!

Originally Posted by Ray

For the first few minutes, I kept saying to myself, "Just break the damned pot, Steve!".

I hear that a lot! lol

Originally Posted by Ray

"Time release" fertilizer is a misnomer; the release rate is temperature-controlled - once wetted for the first time, fertilizer will exude continuously, faster when it's hotter and slower when it's colder, so be sure to purchase one that "sync's" with your growing conditions. Buy one intended for lawns (where it tends to be cooler) and use it in the house or greenhouse, and you might overdo it.

For plants like these that will be repotted pretty much annually, the slow-release fertilizers are quite good, but for a plant that might not be so well tied to a calendar, I'm not a fan.

George Hatfield told us Nutricote (made by Furikan) holds up in hot weather, while Osmocote melts rapidly and has killed his plants before. After 40 days of 100+ degree temps this year, I've still got lots of time release pellets on my plants!

My goal is to repot every 2-3 years, which will be dictated by growth rate.

[Ray]

Originally Posted by isurus79

George Hatfield told us Nutricote (made by Furikan) holds up in hot weather, while Osmocote melts rapidly and has killed his plants before. After 40 days of 100+ degree temps this year, I've still got lots of time release pellets on my plants!

My goal is to repot every 2-3 years, which will be dictated by growth rate.

Be careful - stating to use "Nutricote" is almost as non-specific as saying to use fertilizer, with no other guidance.

I'm afraid George was teaching more than he knew...
Check out THIS CHART at the manufacturer's website. The right-hand column is probably the most relevant.

Osmocote also makes a variety of formulas, many of which have shorter- or longer life spans.

[isurus79]

Originally Posted by Ray

Be careful - stating to use "Nutricote" is almost as non-specific as saying to use fertilizer, with no other guidance.

I'm afraid George was teaching more than he knew...
Check out THIS CHART at the manufacturer's website. The right-hand column is probably the most relevant.

Osmocote also makes a variety of formulas, many of which have shorter- or longer life spans.

Hmmmm... good to know! Thanks Ray!

[Ray]

You'll also note that the chart gives release times at 77°F in the greenhouse. If your average temperature is higher than that, the pellets will release nutrients faster, and become depleted sooner. The converse also applies.

George's experience with Osmocote was probably just a case of using a colder-formulated one under warmer conditions.

[MarinaDC]

Here is more info on Nutricote application and consumption by temperature zones. I use 180, but I am sure there are sheets like this one for every formulation.

https://www.arysta-na.com/Nutricote/...18-6-8_PIS.pdf

[isurus79]

Originally Posted by MarinaDC

Here is more info on Nutricote application and consumption by temperature zones. I use 180, but I am sure there are sheets like this one for every formulation.

https://www.arysta-na.com/Nutricote/...18-6-8_PIS.pdf

After fertilizing for decades with dissolving fertilizer, the time release fertilizer is new to me. Thanks to both of you for posting this stuff. I didn't realize the time release stuff has a lot of variables in the formula.

That said, I had amazing growth last summer with time release with MUCH less effort. I doubt I'll ever switch back to dissolving fertilizer.

[estación seca]

Steve, a U of AZ soil scientist lecturing to our local branch of the rare fruit growers told us no available formulations of time-release fertilizer pellets last more than a couple of weeks in our summer heat outdoors. He told us not to use them on outdoor plants in the summer. I don't know how often you get above 100 F / 38C. He said they're fine for winter annuals and vegetables, and for house plants.

He also told us 100% of ammonium sulfate applied to the soil in summer here is taken up by the plant, or converted to molecular nitrogen by soil microflora, within an hour.

[isurus79]

Originally Posted by estación seca

Steve, a U of AZ soil scientist lecturing to our local branch of the rare fruit growers told us no available formulations of time-release fertilizer pellets last more than a couple of weeks in our summer heat outdoors. He told us not to use them on outdoor plants in the summer. I don't know how often you get above 100 F / 38C. He said they're fine for winter annuals and vegetables, and for house plants.

He also told us 100% of ammonium sulfate applied to the soil in summer here is taken up by the plant, or converted to molecular nitrogen by soil microflora, within an hour.

We were above 100 degrees for 51 days this summer and the pellets worked very well. I've still got plenty in my pots right now.

[Subrosa]

How do these pellets work, from a physical standpoint? Do they dissolve, releasing nutrients, or are they a shell through which nutrients diffuse?

[Ray]

Originally Posted by isurus79

We were above 100 degrees for 51 days this summer and the pellets worked very well. I've still got plenty in my pots right now.

A couple of comments here:

Air temperature does not necessarily translate to pot temperature, especially if they're wet and evaporative cooling can occur.

Having the pellets present doesn't mean they are still releasing fertilizer, as they don't work by slowly dissolving.

Instead, they consist of a permeable polymer pellet containing water-soluble fertilizer. Once the pellet has absorbed water, fertilizer solution starts to ooze out. The rate at which it is released is determined by the porosity of the polymer, and as the polymer has a thermal expansion coefficient, the warmer the pellet, the larger the pores and the faster the fertilizer is released. Different release rates are controlled by modifying the polymer and its thickness.

Your remaining pellets might be just plastic shells.