I've read in a few places that it's a good idea to sterilize your soil-less mix before starting seeds, and it seemed like a good idea.
The directions I saw said 6 minutes in the microwave would do it, but of course I had to improvise. I thought, well, I sterilize canning jars and so forth for 10 minutes, so wouldn't that be better? Well, the soil is in the microwave, and I'm on the phone with the mechanic, when I smell smoke.... I dash around the kitchen, sniffing, phone to my ear, and I track the source to a little tendril of smoke emerging from the microwave. Egad! I turn off the microwave and peer inside, and I see tiny coals among the soil particles. Egad!! Fortunately, the tupperware container isn't melting or anything, and I slap the lid on to deprive my little fire of oxygen. I quickly finish my business with the mechanic, who is probably wondering why I seem suddenly distracted, and I take the container of soil outside to cool down. Egad!!! Who knew??!?!! Well, no harm done, and I'm pretty sure my mix is sterile now!
I though I would pass this story along as a word of warning not to exceed that recommended 6 minutes in the microwave!!
Fire in the hole! Caution about sterilizing potting soil
Also, keep an eye on the turkey oven bags if you use them to sterilize. Had a nice little cookout in my kitchen the other night! Ah, what we will do for our gardens ;)
J
Good to know it's not just me.... LOL
I've dampened the soil mix for use, but it still smells a little smokey (imagine that). Anybody see problems with using it anyway in my containers for winter sowing?
I put mine in the reg. oven on 300 for 1 hr, you can do a nice large pan at a time
I posted this over on the propagation forum, too. It seems heating the soil over 200 degrees can release toxins into the soil!
I have soil heating in the oven now, with a thermometer probe to measure temperature, but upon further googling I've decided to take it out and just rely on the use of hydrogen peroxide water for wetting. I'm not trying to prevent damping off, which has never been a problem for me, and this isn't previously used soil. I'm just trying to prevent fungus gnats, which are really just a nuissance rather than an actual problem, and maybe the hydrogen peroxide will discourage them. I may try again sterilizing soil to use for indoor starts, but I think I'm likely to do more harm than good with the winter sowing I'm trying at the moment...
Thanks for the input!
I used to do the microwave thing but my mom HATED the smell of cooking dirt and forbid me to ever do it again! Lol. Now I just use boiling water.
Funny story though, good thing everything turned out okay!
Hey, I like the boiling water idea.... seems like a fine alternative. The soil may not come out really sterile, but it ought to be close enough to discourage most things that might be in it. Thanks!!
My DH thought it was pretty funny, too.... He asked me what had happened as soon as he walked in last night. I guess I didn't have the back door open long enough! I was pretty amused at the whole thing... at least, I started laughing once I realized the smoke smell didn't have a more serious source!
I bake my starter mix (soiless) in turkey bags at 200F or so. I seal the bags with twisties, lay them sideways on a cookie sheet and flatten them out a bit. I use my meat thermometer to punch a few vent holes in the bags, then leave the thermometer in one of the bags to keep track of the internal temp. When the temp reaches 180F, I leave them in the oven for another half hour. I can reuse the bags quite a few times.
I haven't heard anything about releasing toxins if the mix overheats. My understanding was that hotter temps can kill nutrients, but in the case of starter mix, nutrients are not an issue. I always bake my soiless starter because I re-use it year after year. I have 5 gallon buckets of it in the basement! LOL!
"...rely on the use of hydrogen peroxide water for wetting."
SO what's the deal on this Hydrogen Peroxide water for wetting. Newbie here.
This message was edited Feb 17, 2005 1:22 PM
critterologist ROTFLOL I'm glad you warned me... I would have done the exact same thing. It's just lucky that I'm behind in my chores or I would have been the one who did it and you would be laughing with me!!!
Thanks for the "heads up".
Judy
Heya, Steve!
There have been several threads on using hydrogen peroxide solution for soaking seeds, watering seedlings, misting plants, etc. I'm using it instead of plain water for starting seeds in damp paper towel this year, and I also used it to dampen my seed starting mix. The recipe I've seen is to add 2 oz. of hydrogen peroxide (the 3% solution you can get at the pharmacy) to 1 gallon of water (that's 1 Tbsp. per quart, or a little less than 1 tsp. per cup). I can't comment on whether it really "super-charges" the water in any way, but it makes sense that it would help reduce fungus problems such as damping off.
Here's the link for using it to start daylily seeds: http://daylily6.tripod.com/Step_1.html
I wonder why soiless mix needs to be heated.
Any explanation? What are you supposed to be killing?
This message was edited Feb 17, 2005 9:32 PM
"damping off" is sort of a generic term for sudden death of young seedlings due to a variety of causes, most of which seem to be fungal in nature. Sterilizing the soil should cut down on that significantly by killing the fungus spores. Also, it'll kill eggs of those annoying little gnats and other "baddies," and it should kill any weed seeds that might have sneaked into the mix.
Sterilizing is especially important if you're re-using your soil-less mix. I'm not re-using, but I've had this bag of mix since last spring, so I'm playing it safe. Actually, even freshly-purchased mix can have problems, but I haven't encountered anything worse than gnats and a couple of weed sprouts myself.
Thanks, crit, for Hydrogen Peroxide info. Your answer gives me another question:
"for starting seeds in damp paper towel this year" ---- What's THAT about.
I like to start some seeds this way, especially peppers, and I think it helps with germination. Basically, you wet a piece of paper towel & wring it out a little so it's nice & moist, not dripping. Place your seeds on the wet paper towel. I like to fold it over once or twice (you can still check on the seeds by holding it up to the light) before placing it in a ziplock baggie. Be sure to mark the baggie with the seed variety and the date, as it's easier to lose track than you'd think! When the seeds start to sprout, they can go into their pots, or sometimes I like to put them closer together in a little seed-starting tray filled with wet soil-less mix and transplant them after they get a set of "true leaves" (the second set after the ones that form initially). Occasionally, a sprout will send its little root down into the paper towel & be hard to lift away without damaging it, so if this happens just cut out the little bit of paper towel and plant it right with the seed. Some people avoid this by starting seeds in damp sand (in a covered container) instead.
The other trick I've heard recently is to soak seeds in chamomile tea, weak regular tea (second cup from same bag), or the hydrogen peroxide solution mentioned earlier. Opinions vary on how long to soak, maybe a couple of hours to overnight for pepper seeds, days or even weeks for some seeds with tough, thick coats. This may boost your germination percentage, but for most seeds it doesn't seem vital to success. I'm getting some daylily seeds, and I asked the trader about the method outlined in the link above. She said she tried it one year, and she thought it worked about as well as just sticking the seeds into damp starter mix.
I also get coffee filters at the local dollar General and use them instead of the paper towel. I place the seeds on a damp filter. Fold it over and place either on the fridge or inside it depending if it needs to be cold treated or not. After cold treatment is over they go on the top of the firidge. The filters are as cheap as the towels and are less likely to have roots grow through them.
I like either method and start my seeds like this in the winter time and then place them in pots of soil to grow and even place some of them outside in enclosed pots inside a twist tie gallon baggie, also cheap at dollar general stores.
That's a good idea, Windy. One of things I don't like about the paper towels is that delicate germinating seeds get stuck to the toweling. I'll have to give the filters a try.
Great thread . Thanks for the info. Patti
Cant you just buy sterilized soil Jill................. we can over here!!
ROTFLOLOLOL!!!
When I read this thread's title I thought you found a new way of sparking things up Jill...I didn't realize it was the old thread. he he he
Reminds me of the story of a family friend who heard that his golf balls would go farther if warmed in the microwave....Yeah......they explode.
LMAO.......................................... he really did that?????????????????????????????????
I've read that even "sterilized soil" can be less sterile than you'd think, and certainly if you open up a bag of sterile soil and let it sit around for a few days, its sterility is compromised (although it's probably at least free of viable weed seeds). If I'm dealing with relatively small quantities of potting mix, as for seedling trays, I just run it through the microwave -- no big deal to do, and it also comes through the process nicely moistened.
Yes,Mr C...he did. As they say..."sometimes common sense isn't all that common."
Years ago, when my aunt got her first microwave, I spun her a tale about making the perfect 3 minute soft-boiled egg in 33 seconds... She had the egg in the microwave, but I couldn't be that mean, so I stopped her before she pressed the "start" button. LOL My SIL heard this story over the holiday when the subject of microwaves came up and laughed, said, oh you should've told her that it'll work as long as you remember to poke a little pinhole in the egg! (Just in case somebody takes me seriously... an egg with a pinhole in its shell will still explode in the microwave.)
Egad, she says! Critter, your post made me laugh.
Good information. Thank you! (from the queen of microwave "explosions")
LOL!! How did I miss this and I thought I was the only one! I still use the microwave but I wet down the soil a good bit before I cook it. ROTFL!
Caren
Yes, I moisten the starter mix in the turkey roast bag before I put it in the oven. It actually heats up faster that way.
The oven is definitely better if you need to sterilize larger quantities of potting mix -- but baking the soil in the oven does seem to create an odor!
I had no idea soil-less mix burned so easily until the fire department had to be called to an apartment I was living in 10 years ago....had left an empty container of mix outside on the balcony...without thinking thew a cigarette on top, went back in the apartment and in five minutes the flames were shooting up to the top of the balcony...have never forgotten that lesson.
Yikes! I can see where dry fluffy peatmoss would pretty much be excellent tinder... I hope that lesson didn't leave you literally scortched.
I haven't really noticed a bad smell from baking the starter mix. If I leave it in too long, it does smell a bit chemical. I try to maintain an internal temp of 180F for 1/2 hr. When I really start planting seeds, I'll sterilize two big turkey bags of starter at a time, and I do that every couple days. I have buckets of it downstairs I re-use, and I also buy the 3.5 cubic foot bales, as well.
A Note on Hydrogen Peroxide:
The recipe above for seed soaking or watering seems qite dilute. I am going to try an experiment with this:
1) potted seed using water only.
2) potted seed using dilution of 1TSP/Quart of water
3) potted seed using 25% Hydrogen Peroxide
4) potted seed using 50% Hydrogen Peroxide
Additionally:
Did you know that Hydrogen Peroxide is nothing more than water with 1 extra Oxygen molecule attached.
Being so it can very easily find a stray Hydrogen molecule to attach itself to in the air, thus rendering your
Hydrogen Peroxide (H30) as mere water (H20). Therefore keep your hydrogen peroxide in a tightly closed
container in the refrigerator as it will be less reactive at a lower temperature. In other words, if your making solutions
and not using it to water emmediately, then cap your container.
I generally fill gallon containers with tap water and let them sit for a few days with no lids so the chlorine will
escape.
Q: Does anyone know if distilled water is better than tap water or are the minerals in the tap water benificial to
the plant growth.
1. When you mention 25% hydrogen peroxide and 50% hydrogen peroxide, do you mean dilutions of the standard bottles you find on the shelf at the pharmacy? True solutions of 25% and higher hydrogen peroxide can be very dangerous.
2. Don't forget that hydrogen peroxide is also a bleach.
Regards,
Bobby the Chemist
I think filtered water would be better than distilled.... seems like soaking seeds in truly distilled water would create an osmotic imbalance that could rupture cells and damage the seeds (sort of the opposite of what happens when you salt a slug).... if you water with distilled water, the water has to pass through some potting soil, so that would probably be OK.
What's the meaning of "egad"?
"Egad" is British English for a bad kind of 'Wow'
I used tapwater and don't seem to have problems, but we have well-water... minerals, but not chlorine.
Johnsonjrbm,
Yes I mean 25% AND 50% of the drugstore variety of Hydrogen Peroxide!
It's only an experiment and all I have to lose is a few seeds...
Brian
No offense intended. It's just that every once in a long while I come across someone who's acquired some lab-grade material, and thinks that if one aspirin kills the pain, a thousand must be even better... As a former Safety Manager I tend to err on the side of caution :-).
Please post follow-ups on your trials...