Sterilizing soil in microwave?

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woofie Chewelah, WA(Zone 5a) Apr 04, 2009

I have seen references to using the microwave to sterilize soil for potting. I started to try it once, but chickened out, worried that I would end up exploding my microwave. Has anyone done this? Does it work? Is it safe?

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ecrane3 Dublin, CA(Zone 9a) Apr 04, 2009

Hopefully someone who's actually done it will have some advice, but I think the trick is it's got to be a bit wet while it's being microwaved. You can sterilize in your regular oven too and don't have to worry about exploding, but from what I've heard it doesn't smell too good while it's cooking.

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oldude New Iberia, LA Apr 04, 2009

I have not tried the microwave but I have poured boiling water over some container soils. If you have moisture in the soil it’s going to expand but I would think that it is pours enough that it would not hold any internal pressure. Actually a damp soil would transfer heat much better, but again I do not speak from experience.
Oldude

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woofie Chewelah, WA(Zone 5a) Apr 04, 2009

Thing I worry about is rocks in the soil. Even my supposedly "soil-less" mix has a few rocks in it. And, yeah, I've cooked it in the oven. It takes quite a while and it drives my DH out of the house. He's very understanding, but he does have his limits! Which is why I was kind of wondering about using the micro.

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ecrane3 Dublin, CA(Zone 9a) Apr 04, 2009

Here are some instructions for sterilizing in the microwave"
http://www.colostate.edu/Dept/CoopExt/4dmg/Soil/sterile.htm
http://www.hortmag.com/article/Sterilize_Soil/

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oldude New Iberia, LA Apr 05, 2009

ecrane3
I wonder if those weed seed pop like microwave pop corn? Just kidding but that should not be a problem if you use those plastic food covers that my wife fusses at me about not using.
Oldude

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ecrane3 Dublin, CA(Zone 9a) Apr 05, 2009

I don't think you heat them long enough to pop--I frequently microwave my birdseed to prevent it from germinating if the birdies drop some and none of that has ever popped. If you cooked it for long enough though some of it might!

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docgipe NORTH CENTRAL, PA(Zone 5a) Apr 05, 2009

I have an old second hand yard sale radar oven. It is out in my shed and serves well to brew up a coffee, heat up molasses in cold weather and cook off a pot full of soil on rare occasions. Any such cooking kills all the biology in the soil. If you do that much you may as well use a non-organic potting soil. I paid five bucks for my gardening special radar oven. LOL

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woofie Chewelah, WA(Zone 5a) Apr 05, 2009

Thanks, ecrane3. That's going to make it a bit easier to re-use some of the potting soil that sat out over the winter. That first article was very informative. Didn't realize you could cook soil for too long!

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