Modifying Raybo's 3-2-1 SWC Mix, substitute for Pine Fines

[ruet]

I'd like to mimic Raybo's mix for Self-Watering Containers (and his results!) but pine fines are hard to come by for me here in Spain.

Raybo's SWC mix is:
3 parts Potting Mix (as I understand it, this is just pH-adjusted peat)
2 parts Pine fines
1 part Perlite

I can get the Peat and the Perlite no problem. The best candidate I can think of to replace the pine fines is LECA (aka Hydroton, aka Expanded clay balls) which are cheap and abundant in the 10-20mm range (1/3 to 3/4 inch). Anyone have experience with the stuff? Could I swap LECA for Pine bark 1-1, to make a mix which is:

3 parts pH adjusted Peat (will add dolomitic lime or diluted hydrated lime slurry [no sediment] to increase pH)
2 parts LECA (10-20mm)
1 Part Perlite

Any and all suggestions are much appreciated. My tomatoes are in 18oz cups and are itching to make the move to their final homes within the next couple of weeks, weather permitting.

[rnewste]

ruet,

I am not familiar with the LECA, but is sounds like these may work as a substitute for the Bark Fines. The goal is to try to maintain a light, aerated grow media, where air can reach the root system, while at the same time, moisture can wick up from the water reservoir. Kind of a balancing act, but the 3:2:1 Combo Mix achieves this objective. Also, you may need a Wetting Agent for the peat.

Worst case, if there is insufficient wicking and you start to see your plants wilt, you will need to top water until the roots reach further down into the grow media. You may also want to use a 3:1:1 ratio in a few containers to trial. Keep us posted.

Raybo

[ruet]

Thank you kindly Raybo!

I've started 2 of each variety I wanted to try this year, with the exception of Cowlick's Brandywine which just didn't want to germinate for me more than once (it apparently doesn't do terribly well in high heat anyway...)
One each of 3-1-1 / 3-2-1 sounds perfect. Will do my best to document their progress every so often, Raybo style.

[dice]

I think hydroton may actually work better than bark
fines. It will not break down at all, so there will be no
loss of whatever large pore air space it contributes
over a season. It is not a high-carbon material like pine
or fir bark, so soil bacteria trying to digest it will not
use up nitrogen from whatever fertilizer has been added.

It should be equivalent to replacing the bark fines in
the 3-2-1 mix with turface.

The only issue with hydroton in a mix for a self-watering
container would be lack of wicking, but the peat or coir or
potting mix portion should still handle that adequately.
(Feel free to replace any of the peat with coir, which does not
need a wetting agent.)

[rnewste]

dice,

Thanks for the input on Hydroton. I am just not familiar with it however, my son owns a Hydroponics Shop in Santa Fe and I will ask him about it (as well as a "family" discount).

I agree that the Bark Fines do break down over the course of the growing season. What I recommend in the Guide is to replace 1 cubic foot of the old 3:2:1 Combo Mix at the beginning of the next Season with a modified ratio of 2:3:1. This added Bark Fines mixed in with the rest of the old Mix will help bring the total back into the original 3:2:1 ratio each new Season.

The Hydroton would eliminate the need to do this. Now....ANOTHER MythBusters Project for next year!!

Raybo

[sprtsguy76]

The only thing thats scares me about this product in a swc is the size, I haven't seen anything smaller than 1/2 inch. Do they make a smaller hydroton like maybe 1/4 inch or maybe even better 1/8 inch? I just dont see 1/2 inch peices working that well to help to fully hydrate a tomato plant. JMO

Damon

[rnewste]

Are these the Hydroton balls that you guys are talking about?



Raybo

[rnewste]

I just confirmed with my son that these are indeed Hydroton balls (Above photo from his Shop where he is growing tomatoes as a demo). He says that they come in only one size (sorry Damon).

He sells the 75 Litre bag for $39.00, so they are not cheap. Says he sells about 5 bags per week.

Raybo

[dice]

They do look kind of big there. Those net pots look like about
6-8" in diameter. I see a lot of ads for hydroton that say
"8-16 mm size range". There is one orchid place listing
something called "small hydroton" as an ingredient of their
custom orchid mixes, but I do not know what that means
exactly, and I do not see any other "for sale" ads for it.

Still, 8-16 mm particles would probably work ok as the "-2-" part
in a 3-2-1 self-watering container mix that was half normal
potting mix.

[ruet]

Hi folks,

LECA/Hydroton is available here in Spain (somewhere...) in the 3-8mm range (1/4in-3/4in, roughly) right down to the dust size (0-4mm). I'm still looking for a source for the smaller size, but a 50L bag for the 10mm stuff costs a whopping 4 bucks and is available pretty much everywhere.

Must keep searching...

[dice]

3-8mm size sounds like a winner. One post somewhere said
"3/8 inch average size" for hydroton particles. 50liters is about
13.2 gallons (picture 2 and a half 5 gallon buckets to get a
quick idea of how much volume that is).

It costs several times that much for the same stuff here
in the US:
http://www.horticulturesource.com/pr...oducts_id=1315
http://www.homeharvest.com/hydroponicmediumleca.htm
(Maybe we are paying international shipping to import that
brand name here? Back in the early '90s there was a 5%
tariff on expanded mineral products, too.)

It is good that it is neutral pH. Apparently it is used as a
construction material in some applications (drainage,
insulation, etc). In bulk it would probably be cheaper from
construction materials suppliers than from horticulture
suppliers, but I do not remember seeing LECA products
on the shelf at big box hardware stores (while browsing
the concrete, sand, mortars, etc).

[amideutch]

The Leca/hydroton aggregate is used for growing house plants hydroponically and is available at most gardening stores here in Germany. I use it for this rubber tree/plant in my upstairs room. They will wick to a certain extent and are ph neutral. Ive been growing this plant for about eight years. Ami