Sterilizing potting soil

[Jobe]

Ok, my dillema is in the other thread, this thread is damage control.

I always here the word potting soil, but i believe, for searc "terrarium vermiculite", one result with sterilized potting soil/vermiculite mix...dang!

I think i may have jumped on the 'Sterilised' part.

Now then, whats the best method for sterilizing potting soil :?
Only non-chemical way i can figure is boiling it in a pot or nuking it in the microwave oven...

F1! F1! F1!

 

[JacenBeers]

I usually mist the soil and then put it in the microwave for 15-20 seconds. This usually does the trick. If I saw anything living in the soil before the microwave it was no longer there afterwards. Make sureyou give it time to cool before allowing your spider to touch it.

 

[MrT]

You could bake it in the oven for 4 or 5 hours @ 350 - 400 degs.

That should do it..

E.T

 

[Wade]

Microwaving probably kills off some stuff, but sterilization? Not quite! I have seen ants still moving about on leaf litter that had been in the microwave for 20 minutes!!! Code Monkey wrote pretty extensively about sterilizing recently, but I forget which thread it was. Good stuff, though.

I used to routinly nuke all substrate in the microwave, but no longer do so. I noticed that substrates seemed to be more prone to molding after being micro'd! I suspect that there's natural microrganisms in many substrates that help keep mold under control, but if you kill 'em...I may at some point go back to nuking it if I see any problems, but right now it's a tedious task I'd rather avoid!

One way to help limit the introduction of pests is to keep it simple. Like many here, I favor peat alone (dry cages) or peat mixed with vermiculite (moist cages). Although peat may support a few types of pests, it's nothing comared to what may be in the potting soil (which is a mix of many differen organic materials). The manufacturing process of vermiculite involves VERY high heat, wich does sterilize it. Of course, once you bring it home and start putting live animals on it, it ceases to be sterile.

I have occasionally used the freezer to help control pests when using substrate I've collected, such as leaf litter. Since I only use that for millipedes and beetle larvae, it doesn't have much relevance to tarantulas.

Wade

 

[Code Monkey]

Originally posted by Wade
Microwaving probably kills off some stuff, but sterilization? Not quite! I have seen ants still moving about on leaf litter that had been in the microwave for 20 minutes!!! Code Monkey wrote pretty extensively about sterilizing recently, but I forget which thread it was. Good stuff, though.

I'll just repeat it here again - there are three things you can do to "sterilise" soil, peat, compost, etc (only one of which is actually sterile).

One, the microwave method. Here, you need to really moisten the substrate and probably keep another container of water in the microwave just in case you dry it out. You'll need to microwave at least 3 minutes, and preferably about 8 on high. This isn't truly sterile, but does kill mites and most molds and other things. The catch to microwave sterilisation is that you must heat the entire volume of substrate and as anyone who has microwave large amounts of food knows, that's very difficult.

Two, the oven pasteurisation method. Here you soak the substrate in some deep baking pans and cook at 160 degrees for at least two hours *after* the substrate reaches 160 in the center. Not sterile, but same idea as the microwave method. It's not necessary to bake at higher temps like Mr. T suggests.
(this is from Stamets).

Three, the pressure cooker. Load the substrate into quart jars or something and pressure cook for 45 to 60 minutes at 15 psi. This truly is sterile and basic lab protocol for sterilising solid media, albeit with an autoclave versus pressure cooker.

If you really feel the need to sterilise your substrate, I'd go with the oven method - your home will smell like cooked dirt, but, there you go, it's effective and it works for the sort of application you need.
I personally don't sterilise anything because I believe it is best to have a good, thorough fauna of critters and fungi in there that are typically ubiquitous. Substrate is not sterile, all killing off everything does is hit the reset button - you're more likely to get a pathogenic fungi or arthropod in a recently sterilised substrate than you are with a normal fauna where the intruder would have to compete for its niche.

You apparently had some sort of nematode infestation from what you described. Much like most mites, it's probably harmless (there are nematodes in all soil), but you've got to do what you think is best.

 

[Jobe]

Thanks ppl

great info C_M, will look into it. My mom used to do baking during the holidays and we used to use these huge 3'+ diameter clear top ovens. If i get it from here for this im sure she wouldnt mind...


Yeah, those little white things did look a little harmless, but so did the C.Crawshayi when i first got it home...untill he continueously attacked the chopsticks i used to move things in his KK...
hee hee...mean little bugger...Jobe like