What is the concern with heavy metals in soil?
If you’re looking to start a garden, this will be valuable information!
I read from one woman who has tested soil that potting soil is lower in heavy metals than backyard soil on average. Based on her testing, potting soil averages 100 ppb to 20,000 ppb lead. Backyard soil that is high in heavy metals can be a real threat to kids and is a source of lead poisoning.
What Does “Organic” Potting Soil Mean?
It can be harder than it seems get safe potting soil. I am learning that “organic” or ORMI certified soil criteria is NOT the same as organic food standards. It basically means nothing and may contain factory farmed poultry feathers or industrial compost, for example, or even trash. It just means compostable, not actually organic as in pesticide free.
Best Options for Buying Potting Soil:
The best case scenario is if you have a local organic food farm or nursery that sells compost or soil they have cultivated and you can ask if the inputs were grown without pesticides and has been tested for heavy metals.
If you need to buy bagged soil, I think Coast of Maine is the best choice (I have no affiliation). They have links to heavy metal testing. One of their products I saw said less than 100 ppb. A few were over 1,000 ppb.
Other brands that might be good as far as being organic are: Fox Farm, Espoma, Kellogg (this is likely least expensive), Sungro, Geo Organic. But I’d recommend looking deeper into both potential pesticides and heavy metals that may be residual in their soils. I have not contacted these companies to ask if they do heavy metals or other testing. Ace Hardware’s website links to safety data sheets, but those don’t state a level of heavy metals.
Do note that something like soil can vary considerably from batch to batch, but I do think it’s worthwhile to buy from brands that utilize sources and practices that are likely to minimize toxicants.
How to Make your Own Potting Soil Mixture:
You can also sort of create your own mix of potting soil with the following “recipes.”
1. 40% coir, 30% perlite, 30% vermiculite mix. Add fertilizer if needed.
2. From “Thezenandthehoney”:
10 Lbs Block Coconut Coir
10 Gallons Compost
Perlite 2 Gallons
Vermiculite 2 Gallons
4 Cups Natural Fertilizer Mix (see their site for more info)
Lead Testing Options for Soil or Water:
If you are interested in getting lead testing for soil or water, see links:
One of my readers shared that The University of MN tests soil with ICP (down to 2ppm iirc) for $20. And a recommendation was make sure yours is under 40 ppm for gardening.
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***Thank you for visiting Clean Green Toxicant Free! I started this site simply because I want to help people and share information. I dig deep and seek the most truly non-toxic products, without bias. I am not paid to write anything and I don’t sell anything.***
Another of my blog posts you might be interested in: Avoiding Pesticides and Utilizing Native Plants in Your Yard