Pesticides and/or Herbicides Residual Herbicides

Residual Herbicides in Compost Part 2: On Grow Mix, Potting Mix, Compost, Manure, & Mulch

If you are just joining me and have not read the first part, please read through Part 1 to gain a more complete picture of what is being discussed.


As I mentioned at the end of Part 1, my friend was ready to throw in the towel and not buy anymore potting soil and/or grow mix, compost or mulch.

And I must admit that in this day and age it is difficult to find products suitable for organic gardening, but they are out there.

Below are 3 points I think you will find helpful:

  • OMRI Listed – A Visible Indication of Product Suitability –   Organic Materials Review Institute is a non-profit organization that evaluates products for the organic industry. If the product you are looking at is marked “OMRI Listed” it has been reviewed and is consistent with the requirements of the National Organic Standard.

“OMRI Listed” is indeed a excellent indication of product suitability, but remember something very important when you are buying anything It is always our responsibility to do our homework. As long as we are doing the very best we can do after doing all we can do —-we can then walk forward with confidence.

  • NOP is Not Without Flaws and Inconsistencies –   As with anything, remember that our National Organic Program is not without flaws and inconsistencies.  Nothing seems to be 100% and that is more reason for us to do our homework.
  • Where You Buy Can Be Important –   If you live in a rural area as I do, its almost next to impossible to go to your local feed and seed store and buy something off-the-shelf, of quality that you feel safe about using in your organic garden.  There are always exceptions to the rule, but most of the time you are not going to find the best products in remote areas.

Since I am about 1 to 2 hours from a large city, my trips to the city are carefully planned and when I buy gardening supplies, I try to buy enough to take me through at least a year if not more.

When I was selling lots of starts and potted perennials years ago,  I tried to order grow mix and potting soil directly from the manufacturer but at that time I was so far off the main road they would not deliver.

One more thing to remember when buying any garden product at any place: Clerks — especially when it comes to organic gardening — are not knowledge enough to give you any credible information.  Take what they say with a grain of salt.  I am sure that somewhere on this planet there is an exception to that, but I have never encountered it. Do your homework ahead of time.

Set forth below are my experiences, opinions and suggestions on various products and mulches. Maybe you will share the same opinion and may you will not.  The intent here is to hopefully add to the information you already have. Sometimes having the benefit of someone elses experiences helps us to make a more informed decision about what we want to do.

Pre-packaged Mixes: Grow Mix and Potting Soil:

Only 4 top products are mentioned below.  These are the ones with which I am most familar.

*1 – One of the products that I have used for many years is Premier Horticulture’s Pro-Mix®BX. I buy it in the 3.8 Cubic compressed bale. (INSERTED 2012 – I  NO LONGER USE THIS – BECAUSE OF THE WETTING AGENTS IT CONTAINS.)

It doubles for  grow mix and potting soil. It is basically a general purpose peat-based growing medium with vermiculite, perlite, and limestone.  It also contains Mycorise®Pro which I wish were optional but it’s not. I don’t need a growth enhancer to start seed (the seed has it all). And when I transplant, my organic soil is filled with everything a plant could need without any help from the mix.

Nonetheless, it is an excellent product and has served me well.

The only other option for Pro-Mix®BX is with biofungicide — which I would not use.

*2 – Premier Horticulture has a fairly new product called Pro-Mix®Ultimate Organic Mix that has been OMRI Listed (explained previously). It also contains the “growth enhancer” Mycorise®, which has been approved for organic use. The organic mix has sea-based compost as well and no vermiculite and less peat moss.  (Review the components for yourself here.)  It also doubles for grow mix and potting soil.

From what I can tell it is offered in smaller quantities.  I saw it online in a 32 quart package for $17.25.  This product does not appeal to me at all.  It may be organic, but I don’t see how it would benefit me anymore than the Pro-Mix®BX. Compost is not something I need in my grow mix or potting mix.   My source for Pro-Mix®BX does not carry the Organic and they don’t plan to.  It may be that they think it’s gimmicky as well.

*3 – I know I shouldn’t be surprised, but now there are Scott’s (think Monsanto) Miracle Grow Organics on the market. They are offering Organic Garden Soil and Potting Mix.  In my opinion this is an absolute joke!

If you have not yet researched the Monsanto company, a place you may want to start is an article entitled Monsanto’s Harvest of Fear. If that’s too much reading for you, you may rather start at an article by Jeffrey Hollender who is co-founder of Vermont based Seventh Generation Inc. entitled Monsanto: An Evil Company? You can continue from there if you want to know more.

*4 – The last one I want to mention is Sunshine Pro Premiere Planting Mix – Organically Enriched Composted Blend. I think at one time this was a pretty good product, but in recent years there have been a lot of complaints from consumers that the ph is way off.

I was surprised to find two bags of this in our shed the other day.  They must be at least 5 or more years old and I must have bought them when I could not get Pro- Mix. When I saw that “organically enriched composted blend” on the package after the information given in Part 1 of the article, I didn’t want to use them.

Bagged Compost:

For some reason I have always innately questioned bagged compost long before I knew about the facts in Part 1 of this article.  Thus, fortunately for me, my experience with it is almost nil, but not quite.

I have two bags of Garden’s Alive Gardener’s Gold Premium Compost in the corner of the shed stacked neatly with Sunshine Pro Premiere Planting Mix. It too is over 5 years old. (Go ahead and laugh.  But remember, I’m doing my best to tell you everything about the experience I’ve had with the product and why.)

Since no one ever has enough compost, my reasoning in buying was  – I would have some on hand just in case.   I felt confident about the product when I purchased it, but in view of the residual herbicide incidents that have come to light over the past decade, I would like to find out how this compost tests. Several days ago I emailed them to find out if it has been tested for residual herbicides.  I have not yet heard from them. (Update: And I never did.)

Bagged Composted Manure:

As with bagged compost I have innately questioned bagged manure.  I have however purchased it in the past; maybe 15 years ago.  I don’t think I would ever do it again.  For one thing, I would want to know a lot more about the company, the product, AND the cattle than is available at purchase point. (I am assuming that you know what goes on in the mainstream cattle industry.)

Shovel-Your-Own Manure:

– About 30 years ago I remember Bill and I paying a visit to the cow pasture close to us to get as many “cow pies” as we could pick up to compost and use in the garden.  Armed with gloves, shovels and plastic we picked up enough to make a pile about 3 feet high and maybe 5 feet across. (Gardeners will do anything, won’t they?) We piled it up and left it for a year and when we got  ready to use it, it was filled with grubs.  I ordered nematodes from Garden’s Alive.  We applied them the day we received them and the next day there were no grubs. Yes, that’s right – 0 grubs. I could hardly believe it! Natural pest control at its best!

(The manure worked great by the way, but that was the first time and the last time for that experience.)

– About 12 years ago we were offered some manure from a horse farm.  We got a pick-up truck load.  It was already a year or so old, so we used it right away in the flower borders and selectively in the garden.

– Thinking of the antibiotics used with horses, the feed they are given, and possible residual herbicides from the grass they eat  ——- I would now decline the offer.  Same goes for cattle, goat or sheep manure.  Unless I really knew the people and what their practices are with their animals, I would decline any offer for free manure.  If the animals are fed grass free from herbicides and other organic food and never receive antibiotics or hormones they would be a great source. (And yes, they are out there even if only a few. The hard part is finding them.)

Talk About Timely! I was about to post this article when I received an email from a young woman who had been looking for straw and manure, so I included her story:

-The owners of the property behind her’s board horses.  She just happen to strike up a conversation with a lady who owned one of the horses.  I’ve quoted her words for the rest of the story: “—she (the lady who owned the horse) brought up the fact that her horse manure could not be used to fertilize. She said that the man she buys her hay from has a field next to him that gets sprayed. The chemicals get on the hay. Although it doesn’t hurt the horses, she says, it will stunt the plants in a vegetable garden. She said she found this out because one of her friends was using the horse manure and found this to be true.

“—I was blown away. My daughter and I had just ridden around on the tractor on Thursday to visit a couple of the horse farms here to inquire about manure. Now I don’t know what to do.

Ya can’t even trust horse poo anymore?”

Blood Meal and Bone Meal:

I used these products when I first started gardening.  When I started learning about what goes on with the animals and the processing of these products I stopped using them. It’s been so long that I can’t remember why I even wanted them, except to heat up the compost pile.  (I no longer find this necessary anyway.)

Bagged Mulch:

Bagged mulch was never something I considered, possibly because I have so much area to mulch. Thus, I can’t give you much information on it from experience except that it always looked like a high price for a little bit of mulch.

Loose Mulch:

* Straw –  I order big rolls of straw from a farmer.  Over the years I’ve asked if he sprayed with anything?  He said no.  In reflecting on that, I think it’s a case of poor communication on my part. I will ask again more specifically next time, “Do you spray the fields with herbicide where the straw is grown and harvested?”  I feel he will in all probability say yes.

On the bright side, I have used straw from the same farmer for about 25 years and have never had any visible adverse effects. (To protect your lungs and throat, wear a mask when you pull the big rolls of straw apart.)

(Note: Many years ago I used hay.  Too many weed seeds.  A real nightmare!)

* Wood Chips

(a) We used wood chips (in addition to straw) to mulch for more than two decades.  The particles were small.  They were the remains from a lumber mill many years ago and were dug out of a bog area by the then current owners. Wish I could still get them!

(b) We had a large tree cut down several years back and I had the company shred the tree and leave it in a pile.  Even though it was new wood and some of the chips were bigger than what we  prefer,  we used it around the edge of the borders and it lasted almost 3 years.  We also used it in deep paths in the garden and by the time we wanted to use it in the garden beds it had turned to wonderful black soil.

*Yard Cuttings, Leaves, and Ornamental Grasses

When using yard cuttings and leaves from someone else, the odds of getting non-sprayed material is not good. If you don’t know for sure, don’t use it.

The leaves from our property are gold to us.  If I want them to break down more quickly, we cut them with the lawn mower.

Use what you have on your property.  You can even use a thick blanket of weeds as mulch if you mow them before they go to seed.

When ornamental grasses are cut back in late winter the grass makes a great mulch. (Watch out for the ornamentals that have sharp blades of grasses that cut into skin easily.)

A Helpful Website:

The LII (Legal Information Institute) at Cornell Law School comes up in a Google Search as “Cited as ‘the most linked to web resource in the field of law’ and the best starting place” (for research).  It (the LII) asserts to be known internationally as a leading  “law-not-com” provider of public legal information.

The U.S. Code, Chapter 94, Organic Certification may be found here.  Subchapter 6508 (Prohibited Crop Production Practices and Materials) was of particular interest to me in thinking about this article.


In Part II I have given you 3 points + 1 to take into consideration when you purchase various bagged products. I then set forth my experiences, opinions and suggestions on various products and mulches to use along with your knowledge and experiences when purchasing. In addition, I have given you links to products, information, and articles as well as an excellent website reference to begin further research when you find it necessary.

Final Thoughts

I’d like to emphasize a point that can’t be covered too many times.  Please do your homework.

If you are new to organic gardening this information should have been extremely helpful to you.  If you’ve been around a while, hopefully you still found something that was of help.

In any case, we all realize its still you who has to make the decisions about what you want to do.  No one knows it all and no article is all encompassing. The responsibility is on your shoulders.

A thought to hold and be encouraged by: In my opinion anything out of your own garden is always going to be much better than anything you would buy at the store!


  • Great information! I suspect the straw (from Canada I’m told)i’ve been using in the garden has residual herbicides judging only by how the beans grew initially this year. They have caught up (almost) now, so I don’t know for sure lacking sufficient knowledge regarding the beans ability to throw off the effects of the herbicide. If there is one present. I have been mixing it with equal parts of seaweed and then running the lawn mower over it so it lays down better. Perhaps I should only use the seaweed, but sources of carbon for composting on an island are hard to come by. Organic gardening always presents problems that need solving. Meh.

  • Glad you found the information helpful David.
    Seaweed is great source for compost material and mulch.
    Hope you’ll also have some luck finding leaves and perhaps straw that is free from residual herbicides

  • Thank you for this article. This is our first year gardening and we have to do container gardening. I know that I probably should have used mulch or straw but I really haven’t understood which one is better to use. Thanks this does help, but I will have to research of what options are available around us besides the stuff in the stores.

  • YHM, when you say “mulch or straw” do you mean hay or straw? Would you explain please.

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