Lead in soils, soilless mixes, worm composting

Yes, this is the catch-all soil post!  I have too much gardening to do for separate posts.

First, I wanted to point you to a brand new blog by Howard County MG Yung Cheng with a nice post on soils focusing on lead levels.  And that reminds me to do a soil test for the new part of my vegetable garden… thank you!

Next, after my disappointing experiences last year using a coir fiber-based mix for seed starting, I wanted to do more experimentation, comparing Miracle-Gro products sold at big-box stores.  First, I transplanted eggplant seedlings into peat pots, half using the peat-based potting mix, and half using a new product called Expand-N-Gro, a concentrate of coir fiber and fertilizer to which you add water.

A week after transplanting, all the seedlings are doing equally well.  I would say the coir fiber product works fine as a potting soil.

The other experiment was growing tithonia (Mexican sunflower) from seed, using my egg carton method.  Half the seeds were put in Miracle-Gro seed starting mix (on the left) and half in the Expand-N-Gro (on the right).  You can see the difference.  The seed starting mix seedlings are all doing fine; the coir fiber side produced one viable though smaller seedling, one tiny shrunken one, one that’s pretty much dead, and three total duds.

So, based on these results, I would not try using Expand-N-Gro to start seeds.  The product is not marketed as a seed starting mix, so the experiment may be a little unfair, but since I had similar bad results last year using my own mix of coir fiber, rice hulls, and worm castings, I am personally off the stuff until reaching the transplantation stage at least.  I heard from one commenter last year who’d had a bad experience with the Jiffy Starts that use coir fiber rather than peat moss.  There are a lot of coir fiber mixes out there now, and I’d love to hear from anyone who’s had good or bad results with them.

Finally, if you’re interested in following my adventures as a novice vermicomposter, you can check out my Aunt Erica’s Worm Farm tag on my Rogue Eggplant blog.  I promise to have a new update soon on efforts to put down the Worm Rebel Alliance.

12 Comments on “Lead in soils, soilless mixes, worm composting

  1. Always great see the results of, side-by-side comparisons. With lots of new products out there it's hard for any of us, let alone newbies, to know what to buy and use.

    I like to use transplant mixes (light and porous bu not as finely milled as seed starting mixes). Some name brands are Pro-Mix, Metro Mix, Organic Mechanics, and Fafard. These mixes work for ALL vegetable seeds and most flower and herb seeds.


  2. This year, I used some coir fiber for seed starting, as well as regular seed starting mix. Here is my experience: seedlings started in coir fiber did not do nearly as well as their siblings in other seed starting material. No comparison.


  3. Glad to see the results. I used Miracle Grow seed starting mix and have trasplanted the starters into Miracle Grow potting soil. Everything looks good.


  4. But what do you think about the environmental impacts of using Peat moss, being a non-sustainable resource?


  5. That's why I was checking out alternatives to begin with – though it is a complicated subject, and coir fiber isn't entirely innocent in this regard due to long-distance travel. I'd rather use locally-produced compost for soil amendments than either of the above, but by itself compost isn't the right substance for seed-starting. Let's all keep experimenting and trying out the new choices the market presents.


  6. Have you tried Vermiculite? Seems to be the new 'IN' thing at the moment. It's organic and it's a mineral. I haven't tried it yet, but I'm about to start mixing it with my compost/soil as it holds water really well. They use it in Hydroponics too.
    There are different grades and the finer grade is better for seed raising, courser for mixing in the veggie patch. (Otherwise it gets waterloggered) 🙂
    That's just the info I've researched, not by personal experience. Just thought I'd share or if you have tried it yourself, what's your take on it?


  7. I haven't tried it by itself. It's a component in many potting soils and has been for years. If you research more you'll see reports about asbestos contamination in vermiculite, but apparently that was just a problem with one mine some time ago, and what's on the market now should be safe. Nevertheless, it's best to keep the stuff wetted down while working with it because it makes dust which isn't great to breathe in.

    If you try it for seed-starting, report back! I will look for the finer grade and give it a try too.


  8. I've been using the coir fiber bought from Burpee for 2 years now and have had great success with it for starting tomatos and peppers.


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