Best way to sterilize coco coir?

zebracake

Member
So I've been growing without problems for the last 2 years and all of the sudden I can't get past the seedling stage because they damp off. I flushed the coco with 1ml per gallon of 35% peroxide and 2ppm of chlorine and still getting damp off. Should I just throw the coco out? I've never dealt with anything like this I had no idea weed could be this fragile.
 

zebracake

Member
referring to the concentrations on this website: https://coir.com/growing-medium/how-to-sterilize-coco-coir/

20ml/gal bleach
or
9ml/gal 35% peroxide

I let it sit in solution for a couple of hours stirring a bit. If the issue is contaminants that should take care of it.
Thanks. You know the percentage of chlorine in the bleach? I use pool shock with 68% chlorine but can do the math on liquid bleach. I'm also thinking about starting seeds in rockwool cubes rather than peat pellets. Does rockwool dry out quick enough to not get damp off? I think that's part of the problem with my coco it's not drying out quick enough.
 

ounevinsmoke

Well-Known Member
Thanks. You know the percentage of chlorine in the bleach? I use pool shock with 68% chlorine but can do the math on liquid bleach. I'm also thinking about starting seeds in rockwool cubes rather than peat pellets. Does rockwool dry out quick enough to not get damp off? I think that's part of the problem with my coco it's not drying out quick enough.
I never grew in coco and a rockwool cube may be your answer, but from my experience rockwool cubes can be oversaturated with water as well so you kind of have to get the saturation part down. I go with the rapid rooters because they dry a bit more evenly and hardly if ever become over saturated. Good luck with whatever you choose!
 

Billy the Mountain

Well-Known Member
It is possible to over-saturate a rockwool cube but it's also easily avoided.

Simply shake the cubes after soaking to remove the excess water as stated in the instructions.

I've had near 100% success using rockwool for seedlings and clones
 

zebracake

Member
It is possible to over-saturate a rockwool cube but it's also easily avoided.

Simply shake the cubes after soaking to remove the excess water as stated in the instructions.

I've had near 100% success using rockwool for seedlings and clones
Any size recommendation? I just ordered 1.5inch but I want them to be big enough for the root system to get big enough before transplanting.
 

austin98

Member
Thanks. You know the percentage of chlorine in the bleach? I use pool shock with 68% chlorine but can do the math on liquid bleach. I'm also thinking about starting seeds in rockwool cubes rather than peat pellets. Does rockwool dry out quick enough to not get damp off? I think that's part of the problem with my coco it's not drying out quick enough.
I used 7.5% sodium hypochlorite which is just standard disinfecting bleach from the store

I also just plant directly in the coco with some tap water. cuts out the middle man and avoids some potential problems, just make sure to rinse out the bleach or poolshock solution, buffer, and rinse again so it's not too hot for the babies
 

Wastei

Well-Known Member
So I've been growing without problems for the last 2 years and all of the sudden I can't get past the seedling stage because they damp off. I flushed the coco with 1ml per gallon of 35% peroxide and 2ppm of chlorine and still getting damp off. Should I just throw the coco out? I've never dealt with anything like this I had no idea weed could be this fragile.
Environment. Do you have a light fan blowing across the soil surface? That's how I sorted all my problems with damp/wilt of many years ago. Hope that helps, cheers!
 

zebracake

Member
Environment. Do you have a light fan blowing across the soil surface? That's how I sorted all my problems with damp/wilt of many years ago. Hope that helps, cheers!
Yeah I just tried my next batch of seeds in rockwool cubes and all of them died of damping off again. The cubes weigh 3.8g dry and 38g wet. I let them stay at 20g wet and I still got damping off the cubes barely seem wet at 20g. The bottom tips of the taproot are brown so based on my recent experiences I'm basically not allowed to water my seedlings even though that's what I've always done. 85F degrees 40% humidity, and 1ml per gallon of 35% peroxide and I put cinnamon around the base as an anti fungal. What's the most peroxide seeds can handle? My best guess at this point is that I have airborne fungus' constantly circulating throughout my house and there's nothing I can do about this. My next batch of seeds are germinating in 1% peroxide solution for 24 hours then transferring it to normal water to finish germinating then I'm going to start them in peat pellets on my patio outside in the shade. How soon can I put them in direct sunlight? This has gotta be the most bizarre thing I've ever dealt with. I've gone from starting seeds with 95% success rate for 2 years straight to not being able to start anything at all this shit is fuckin psychotic.
 

Rurumo

Well-Known Member
I'd get some Southern Ag Garden Friendly Fungicide and just drench your media with a solution of it prior to planting seeds. And give your seedlings fresh air, don't cover them with a dome or anything, as well as good air circulation.
 

zebracake

Member
I'd get some Southern Ag Garden Friendly Fungicide and just drench your media with a solution of it prior to planting seeds. And give your seedlings fresh air, don't cover them with a dome or anything, as well as good air circulation.
Sounds good thanks for quick reply. The humidity and temp is high where I live so no dome necessary. How much fungicide should I use for a seedling? I don't wanna overdo it and from what I'm reading it's used as a topical spray not a root drench.
 

Astral22

Well-Known Member
If you think you have airborne fungus, a UVC lamp + ozone could be a good investment to sterilize the room and equipment.
UVC bulbs with short wavelength at 185nm or less will create ozone. UVC will kill germs on surfaces, ozone will reach behind surfaces.

They're not too expensive either, and it's easy to calculate how much UVC you need.
For example, my lamp costed 60€. It's 60 watts, covers a 60m2 room over 1 hour. It has a remote control and a timer, so for example you can use 15mins for a 15m2 room. Just remove any plants, don't look at the light, and vent out the room for at least 1 hour after, don't breathe the ozone, toxic for lungs. And it smells bad, like burning metal wire.

Maybe even look at air purifiers. Some air purifiers come with UVC lamps which don't create ozone, above 185nm. But they will kill anything they suck in. Combined with a HEPA filter, it's pretty useful.

Clean out the AC unit as well while you're at it, not just the filters but needs to be taken apart and look for mold. Best to call a professional AC service.
Clean out any fans you have in your tent.
 
Last edited:

PadawanWarrior

Well-Known Member
Thanks. You know the percentage of chlorine in the bleach? I use pool shock with 68% chlorine but can do the math on liquid bleach. I'm also thinking about starting seeds in rockwool cubes rather than peat pellets. Does rockwool dry out quick enough to not get damp off? I think that's part of the problem with my coco it's not drying out quick enough.
The thing about bleach is it's sodium hypochlorite, so it's got salt in it.
 

PadawanWarrior

Well-Known Member
Pool Shock got just as much sodium as bleach since sodium hydroxide is used in both of the manufacturing processes. Pool Shock is 65% pure, rest is Sodium Carbonate, Sodium chloride etc.
The stuff I would use would be Calcium Hypochlorite. That's what most people use for plants. I've used a bunch of different shit in my hot tub.

 

PJ Diaz

Well-Known Member
The stuff I would use would be Calcium Hypochlorite. That's what most people use for plants. I've used a bunch of different shit in my hot tub.

I only use pool shock for cloning and general sterilization, and like you say it's Cal-Chlor based: https://hthpools.com/products/hth-pool-care-shock-advanced

Sounds good thanks for quick reply. The humidity and temp is high where I live so no dome necessary. How much fungicide should I use for a seedling? I don't wanna overdo it and from what I'm reading it's used as a topical spray not a root drench.
I use Southern Ag GFF in my coco feed at a rate of 1 ml to 5 gal solution.
 

Nrk.cdn

Well-Known Member
I like the bubbler for clones. Straight tap water in a coffee cup takes longer and works quite well.
 
Top