this post was submitted on 08 May 2025
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Hydroponics

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A community dedicated to every form of hydroponics, a technique for growing plants without soil.

Everything regarding hydroponics is welcome here - from your houseplant in LECA to big scale commercial farming.

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I designed and printed these adapters, which fit into used glass bottles. I use them to grow lettuce, basil, and more.
I will publish the files very soon and also make a post about them :)

Right now, I'm trying different materials to use as substrate for holding the seeds, but most I tried sucked in one way or another.

  • LECA is too coarse, and the balls roll out.
  • Coco coir is washed out quickly when filling the bottles/ when raining, and rots in the nutrient solution
  • Polyester filling (used for pillows) is either completely soaked, or bone dry, but works reasonably well
  • PVA sponges become too hard when dry
  • Cotton/ other cellulose stuff (towel, etc.) decompose too quickly

Can you suggest me other materials that would be best suited for that purpose?

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[–] [email protected] 2 points 18 hours ago (1 children)

Spagnum or some other moss (preferably home grown). if you buy it make sure to get the stuff that is still slightly alive (dried not toasted else it will rot and not work very well.

Most "sustainable" sources aren't all that sustainable, but its my favourite substrate nonetheless, I'm currently trying to grow it myself (not very sucsesfully tho)

[–] [email protected] 2 points 18 hours ago* (last edited 17 hours ago)

Great suggestion! I totally forgot about that! Spongy, wicking, doesn't degrade fast, and the best thing: I'm also currently trying to grow it myself!

(Still learning tho.)

I collected many different samples from different places (forest, concrete, etc.) and see what thrives and what not

[–] [email protected] 2 points 1 day ago

Maybe perlite?

[–] [email protected] 3 points 1 day ago (1 children)

Use something coarse like ceramic balls. Drill some holes in your pieces level with the top of the substrate. Use pieces of wire or paperclips through the holes to hold the substrate in place.

[–] [email protected] 2 points 1 day ago

I already tried LECA, and too coarse stuff lets all the seeds fall through.

Also, I don't want to fiddle around too much

[–] [email protected] 2 points 1 day ago

Fine grade wood, or a rocky mix like used for cactus or bonsai?

[–] [email protected] 2 points 1 day ago (1 children)

Rock wool is good for hydroponics. It's not good to handle bare-handed or breathe in because it can splinter, but it won't have anything harmful in it that is unsafe for edible plants

[–] [email protected] 1 points 1 day ago

I would prefer something less hazardous and what's available everywhere maybe