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What would be the best "substrate" for these Kratky bottle plugs to hold seeds or cuttings in place?
(slrpnk.net)
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?
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
I would prefer something less hazardous and what's available everywhere maybe