What are the LECA or other S/H media options available, anyway??

[Discus]

It depends how friendly the store is, I guess. Some might actually be the kind of people that would be "oh, you want to optimise your growing, sure you can have a cup of this for free/minimal cost"...

I agree buying a 50l sack for a cupful of material is a little excessive...

I'm currently running a little experiment to see how well some hydroton wicks inside one of these, which I received 3 of as a wedding gift.

Not sure what I'll put in them, as pretty much all the orchids I reckon would put up with that have root systems that will never cram inside there. I have some Nepenthes that might manage, however...

[rosemadder]

Originally Posted by Discus

It depends how friendly the store is, I guess. Some might actually be the kind of people that would be "oh, you want to optimise your growing, sure you can have a cup of this for free/minimal cost"...

I'm sure that would be pretty easy at a place selling it in bulk, but most I've seen seem to have it in the big bags, and it's unlikely they'd want to ruin the packaging to hand out just a little bit.

Originally Posted by Discus

I'm currently running a little experiment to see how well some hydroton wicks inside one of these, which I received 3 of as a wedding gift.

Ooh! Awesome. I've been wondering about that, myself! Let us know how it goes.

I'd really like to just put various things in different containers and simply measure how high the moisture travels.

You're right, Hydroton doesn't seem to wick all that far-- although, it's been enough to support plants considerably larger than my mini little orchids. I've got a plumeria cutting happily sprouting in the stuff in an 8" or 10" pot (I didn't even look up plumeria instructions, I just stuck it in there!), and an even bigger pot for a small rubber tree that doesn't seem to be doing too badly so far. I used it for a spider plant, some english ivy (I have two, one is still in soil and the one in S/H is growing two or three times as fast), a freshly sprouting Gloriosa Lily root, maidenhair ferns, and a rabbit's foot fern too. I am on the hunt for a material more irregular in shape so it doesn't shift around so much, for sure. But I digress...

[DTEguy]

I think faster wicking substrate might not be better, but I am not completely sure and would like to discuss about it.

Lets take hydroton for example--since I now have some experience with it. It is true that Hydroton doesn't wick fast enough for the upper layer to be consistently moist but it does wick far--about one inch of upper drier layer in my condition and doesn't change much with narrower/taller pots.

However, what exactly is the advantage of a moist upper layer if the roots will eventually grow deeper?

-Some might argue that it will help new roots receive moisture sooner, true. But I haven't seen new root tips dry out.

-Nutrition delivery should not be an issue either since fertilizer ions will diffuse if it's moist.


A fast wicking substrate however can create potential problems such as:

1) too moist for the rhizomes and possible rots

2) salt accumulation. Greater exposure to air on the top and drying occurs on one single horizontal level; right at the base of your plant and rhizomes.

3) Greater capability to hold salt/fertilizer.
- Assuming that different LECA is made of roughly from the same material. The one that is wicking faster is most likely because it can transfer more solution from the inside pores/channels. Why does one wick more than others? Finer pores? More numbers?

I don't think fertilizer can be flush out from these pores in one shot and will require soaking.

But, if it's easier to go in, it's easier to come out....vice versa

4) If point #3 is true, then faster wicking means less air inside substrate; which explains why hydroton is more floaty than most. Inside air might be important in the long run if you cramped out the space in between with roots.

[Ray]

You need to keep in mind that your overall growing conditions play a HUGE role in determining the effectiveness of any potting medium.

The wicking rate of any type of LECA (or other inert medium) is a fixed factor. How rapidly the water evaporates is the variable, and not only does it vary environment-to-environment, but it can change with the weather and seasons.

Ideally, in semi-hydroponics, you want the medium to stay constantly and uniformly wet throughout the pot. As long as the medium stays wet, the fertilizer salts will stay in solution; if too much of the solvent (water) evaporates, out drops the solute - the fertilizer - in the form of mineral deposits that are difficult to redissolve.

So basically, if the LECA wicks better, and/or if the conditions are such that evaporation is slow, you need to water less frequently to maintain the medium in a "pristine" state for a longer time period.


Ray Barkalow
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[rosemadder]

Floaty LECA is most likely caused by interior air pockets that are sealed and never absorb any water. Dead spaces.

More wicking may also mean that more of the spaces in the medium are filled with water. A wetter pebble may actually have considerably less total surface area and potentially less evaporation.

The overall wetness could also be a big factor for the plants, depending on their tolerance for it.

I'm also curious about zeolite, that draws in water quite well and has a VERY high CEC-- maybe even too high. It's a great addition to aquarium substrate. Anybody tried it for S/H?

[DTEguy]

I agree with the possibilities of what you mentioned.

But the air pockets are most likely not sealed, as they sink immediately when you boil them.

[rosemadder]

They do?? Wow, interesting!

[Discus]

Hmm, I shall have to try the "boil it to sink it" method sometime Thanks for the tip DTEguy.

Re: Zeolites, they're only good in aquariums for a short time, (at least as an ammonia reduction agent) as they "fill up" and then start to release it (or bacteria start to "feed" on it), which then spikes your nitrite (and then ultimately nitrate). Not sure how they'd perform in plant culture, but I imagine there will be papers out there...

[DTEguy]

Originally Posted by Discus

Hmm, I shall have to try the "boil it to sink it" method sometime Thanks for the tip DTEguy

We want the air tho! :P..I boiled for intial cleaning to leach salts.
Boil and let it sit to sink. I think the negative pressure will suck water in as it cools slightly.
The air will return as you use it.

It will also sink if you let it soak for a long time.

I guess my point is, less wicking = More air.... At least for LECA

[rosemadder]

I had some hydroton sitting in water for something like a month, and only a littile of it ever sank.

Originally Posted by Discus

Re: Zeolites, they're only good in aquariums for a short time, (at least as an ammonia reduction agent) as they "fill up" and then start to release it (or bacteria start to "feed" on it), which then spikes your nitrite (and then ultimately nitrate). Not sure how they'd perform in plant culture, but I imagine there will be papers out there...

I do planted tanks, and I don't use zeolite for chemical filtration. Yeah, it picks up ammonia-- and plenty of other things-- and hangs onto it where roots can eat it. I will keep an eye out for some in the suitable size range.