Grow mediums - science fair time

Southpac-hydroOctober 20, 2013

Yowke and Aloha,

I've been running my outdoor hydro setup for the last four months with some successes, some utter failures.

bumper crop of cucumbers, losing battle with spider gnats on the green beans, total strikeout with melons, nice meal of collard greens......having fun with blossom end rot with tomatoes now.

onto my the reason of my posting.

My kid is at the age where he wants to participate in the local science fair. i thought about building a solar hydroponic setup, but after reading the rules about scientific methods and experimentation, it seems that having a dad who can build stuff doesn't quite qualify as a good experiment, so back to the drawing board.

Since I live on an island, my thinking was to conduct and experiment with growing mediums "naturally" available, and how they would compare in growth rates....I'm still going to do the solar bit, WTH, coolness factor.

The practical "natural resource" options available are coconut husks, shells and coral skeletons (mind you, this is a elementary school project, not a PhD dissertation). I thought about sand, but dont see al way of keeping it in the net cup, and dont want to foul my system.

with this said, does any one have any experience with processing of coconut coir?

i assume steaming or boiling the medium would be step one.

any perceived issues using coral skeletons and shells?

thanks in advance for any input.


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What up Chuck? Lonnie from upper Michigan.
I Just wanted to say that I have a step-uncle in (Helio?) That's not spelled right is it?
I know nothing about coconuts. Kinda boring.
I always thought there must be a way to harness the tides power to grow something hydroponically. Now doesn't that sound more exiting.
Yeah, I'm somewhat of a jerk!

    Bookmark   October 20, 2013 at 8:50AM
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Me again Chuck. I meant a "small scale" tide experiment of course. I supplied the idea, you design it!
If you're having problems with spider-mites, you can order Predatory Mites over-night from California. Oh wait, I don't know about an Island delivery. They do work awesome though. go to garden pest control.

    Bookmark   October 20, 2013 at 9:04AM
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its 1:21 in the marshall islands...isnt it a bit early for margaritas in the states?

seriously, my budget is 20 bux for this experiment and im a good 300 yards from from the ocean side of the island....a bit closer to the lagoon side.

you can get tore up messing around with the waves on the ocean side, plus i think folks might have something to say about an extension cord running 300 yards across folks yards and streets.

as far as mites, meh the green beans didnt come in full and lush, i dont think im going to grow them again.

    Bookmark   October 20, 2013 at 9:20AM
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Wow! You're eight hrs. behind me. Go back to sleep dream weaver...

    Bookmark   October 20, 2013 at 9:38AM
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PupillaCharites(FL 9a)


I guess the purpose of the project can be to evaluate whether the lime-based shells and coral skeletons to check phosphorus availability.

Better yet, lava rock is a decent medium. Instead of fooling with the former calciferous marine life stuff that will probably slowly dissolve at hydroponic pH's, why not evaluate different types of localities of lava rock as media?

    Bookmark   October 20, 2013 at 1:31PM
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unfortunately,lava rock does not exist out here, unlike being abundant in the Hawaiian islands.... i might look at other fibers, such as palm fronds.

    Bookmark   October 20, 2013 at 6:51PM
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PupillaCharites(FL 9a)

Oops SP, I always thought bikinis were named after the bomb that blew the Volcano over there on Bikini Island ;-). BTW Did anyone ever like Jimmy Buffett music on that side of the world? Volcano

Shows my view is a little screwed up since I also imagine Hawaiian steel guitar music waving with the palms :(

OK, this is a longshot, but if you live in a bunch of atolls, the volcanos must be somewhere shallow. The longshot is maybe there are more deposits of interesting lava rock than anyone much has bothered to look for. Check out this book, and in advance, please don't jump on me for getting technical I- I didn't write the book and it might as well be Timbuktu from my vantage in Florida ... but they seem to talk aboput what might be quarries and maybe they are easier to find if anyone had a reason to look for them? Just thinking out loud, since I know you guys in the islands are always looking for stuff from the mainlands, there ought to be some stuff (besides lots more coconuts) that you have over us!

Google Scholar link of complicated old book with surveys of rocks from the Marshall Islands that looks promising at first glance but requires a teacher to make you read

Just trying to be helpful. Wish I could be in the South Pacific at the moment, but maybe I can afford some Kona coffee and a cheap CD...

    Bookmark   October 20, 2013 at 8:30PM
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Reaching back about 40 years to my own science project, I compared growth rates of radish seeds in various mediums. I used sand - fine, medium, and coarse and used the same nutrient solution on each one. I have no recollection of what the final result was. I do remember that I measured growth not only by height, but by total weight (after gently removing the plants from the grow medium).

    Bookmark   October 23, 2013 at 12:03PM
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If you're going to weigh them either weigh the whole container immediately after saturating the medium to get a baseline and do the same at each interval, or cut the plant off at the crown to weigh them, thus taking the medium out of that part all together.

    Bookmark   October 24, 2013 at 7:41AM
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