From

Location

Message

Date Posted

Appalachian Mtns.

Just what is meant when growers say they use "sterile" potting mix?

No matter what it may say on the package there is no such thing as sterile soil unless it just came straight out of an autoclave.
With that being said, what's the difference between "sterile" and typical potting mix?

Open for discussion....

4/23/2003 6:17:06 AM

Ctpumpkin@optonline.net

Weed free. In theory the heating kills pathogenic fungi. It probably does kill some causal pathogens. But since spores are airborne, this probably doesn't last long enough to even get the material bagged.
I know folks who bag mulches & soils. I've asked if they are willing to accept any liability in making sterility claims. Blank stares. I've even found Yellow Nutsedge contamination of "sterile" Peat based materials.
The value of the natural gas required to heat a soil medium to "sterile" exceeds the fair market value of the finished soil. So I don't put much stock in this theory.
A truly sterile soil wouls also be lacking in beneficial fungi & bacteria. So pathogenic organisms would be better positioned to cause trouble if they're allowed to innoculate the soil unchecked. Because it's impossible to monitor the demographic residency status of your soil medium without large lab expenses, it's not a bad idea to innoculate soils with beneficial organisms yourself at planting. It can't hurt at any rate.

Steve

4/23/2003 6:44:08 AM

Cornwall UK.(50N 5W)300ft.

"sterilized soil" generally means pasteurized.
apart from killing weeds pests and diseases,organic matter in the soil gets broken down by heat and the good bit is ammonifying bacteria survive at 180f they then have no competition and multiply causing a natural flood of Nitrogen.
It may not be totally sterile but it works for me.

4/23/2003 10:02:38 AM