Microwaves Can Sterilize Potting Soil: Careful wtih that fluffing!

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Microwaves Can Sterilize Potting Soil

By Gymgirl
August 29, 2011

Use an old microwave oven to sterilize seed starting mix! Wet the mix evenly, and nuke it for 20 minutes. Quickly fluff it up to release the steam, and cover with a clean bucket lid for 10 minutes. Re-fluff and cover until just warm.

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Name: Critter (Jill)
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critterologist
Aug 28, 2011 6:26 PM CST
Fluffing to release steam sounds like a good way to get burned; please be careful!

It works fine to cover loosely, microwave until it steams up pretty well (10-20 minutes depending on your microwave and on how much you're doing), then put the cover on tightly -- it will continue to steam and will cool down gradually. If it's steamy for at least 10 minutes altogether, the soil will be sterilized.
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Name: Holly
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HollyAnnS
Aug 28, 2011 6:53 PM CST
Thanks, I hadn't heard this tip before.
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Name: Patricia
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patrob
Aug 28, 2011 7:05 PM CST
I don't do any fluffing and just let the mix cool on its own. Works great.
Name: Renée
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KyWoods
Aug 28, 2011 7:51 PM CST
Ya know, I've been wondering if you could use a microwave for that. Thanks!
Name: Evan
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eclayne
Aug 28, 2011 8:03 PM CST

Plants Admin

Nice tip, thanks.
Evan
Name: woofie
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woofie
Aug 28, 2011 8:48 PM CST
You can also use a ziplock bag. Just make sure there aren't any rocks in the soil you're sterilizing!
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Name: Linda
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Gymgirl
Aug 28, 2011 10:50 PM CST
Critt's right about being careful! There's a lot of steam built up.

The only reason I fluff in the first place is to get the sterilized potting mix cooled down in a hurry, 'cause I'm usually ready to sow seeds right away!

Linda
Name: Karen
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kqcrna
Aug 29, 2011 5:58 AM CST
I use a covered casserole.

Beware, this process does make your house stink! I take it right from the microwave to outside to cool, try to minimize the stench in the house. The microwave will be stinky, too. I clean it afterward with an antibacterial cleaner, then let the door stand open for a while.

Karen
Name: Linda
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Gymgirl
Aug 29, 2011 7:47 AM CST
I've noticed the earthy smell only lasts as long as the mix is hot and steamy. As soon as it cools down, no more earthy smell...you'd never know it was there...
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Name: Renée
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KyWoods
Aug 29, 2011 10:27 AM CST
Hmm, wonder if you could do this on the grill....??
Name: Connie
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pardalinum
Aug 29, 2011 11:37 AM CST
I've been doing this for some time. It's when you use regular garden soil that it really stinks up the house and continues to linger. Commercial potting mixes and seed starting mixes, not so bad.
Name: Linda
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Gymgirl
Aug 29, 2011 11:47 AM CST
I'd like to ask what the occasions would be for sterilizing regular garden soil? Confused
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fiwit
Aug 29, 2011 12:03 PM CST
Gymgirl said:I'd like to ask what the occasions would be for sterilizing regular garden soil? Confused


When you can't afford to buy the fancy stuff? Shrug!
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Name: Connie
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pardalinum
Aug 29, 2011 12:25 PM CST
I have mixed regular soil (around here, it's a clay) with potting mix to provide a better mix for some of my plants and seedlings, especially lily seedlings. Most potting mixes available here have way to much peat in them or way too much ground up bark. I think by mixing in some of my garden soil it holds nutrients better.
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Sheila_FW
Aug 29, 2011 12:51 PM CST
Sounds like a good use for a garage sale microwave to put in the shop!
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kqcrna
Aug 29, 2011 12:56 PM CST
I just use my kitchen microwave Shrug!

Karen
Name: Linda
SE Houston, Tx. (Hobby) (Zone 9a)
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Gymgirl
Aug 29, 2011 1:19 PM CST
I did too, until I found a much LARGER used one, for almost free! Hurray!
Name: Critter (Jill)
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critterologist
Aug 29, 2011 1:34 PM CST
I got that "stink" when I sterilized potting mix in the oven, but the microwave seems fine... maybe because I use a covered tupperware-type container? Of course, the first time I tried there was an awful stench, because I didn't realize I needed to wet the mix thoroughly, and it caught on fire! Little glowing smoky coals! LOL
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Name: Karen
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kqcrna
Aug 29, 2011 1:50 PM CST
Obviously playing with dirt is not for the faint of heart!

Critter, I agree, cooking in the oven in much worse for the stench factor, but I definitely get it with the microwave, too. Just not quite as bad.

Karen
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dahlianut
Aug 29, 2011 3:54 PM CST
OMG dear critter about the fire :O That's a good point though. Peat is EXTREMELY flamable and alot of mixes contain a high content of peat so everyone please be carefull and play safe Group hug

Good tip gymgirl Thumbs up

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