I have been doing some gardening over the decades and I am very annoyed by the yellow and orange beads in my (about 160) pots which are the plastic remains of Osmocote. They never dissolve away and I recall being told that they would disappear.
I have found that many others agree with me, after a google search.
So I will never use Osmocote again… those yellow balls will outlast uranium waste…
So why don’t we start a campaign… Can we start by requesting Bunnings to no longer sell Osmocote (Troforte is better (and no, I dont have any shares in them!) . They have brown/ black beads that you cannot see and also dissolve anyway. They are sold by my local (very good) plant nursery.
From a google search…
1.0 out of 5 stars NOT BUYING OSMOCOTE ANYMORE – TERRIBLE FOR THE ENVIRONMENT
Reviewed in the United States on May 8, 2018
I had been buying Osmocote for years. The fertilizer is terrific, my plants loved it and so did I. I don’t love it anymore. Approximately five years ago, I’m guessing, the fertilizer consisted of small solid balls of fertilizer that fed the plant and dissolved over time. Now, that small ball is no longer a solid ball of fertilizer but a plastic ball covered with fertilizer. When the fertilizer dissolves off, you’re left with dozens and dozens of small white plastic balls in your soil. We don’t need more plastic introduced into the environment. I’ve seen birds trying to eat the plastic balls! I am angry that this manufacturer is now giving us a product that’s terrible for the environment and fools us into buying a product which is likely 1/2 solid plastic. I will no longer buy Osmocote for these reasons.
and
The yellow granules are not fertilizer, but the medium that holds the fertilizer. They won’t dissolve as mentioned, they allow for a slow release of the ferts. That’s the downside to osmocote.
Osmocote sold (and made) in the US uses a polymer resin as a coating on their pelleted fertiliers. The coating provides a barrier to moisture, thus giving the fertiliser the claimed slow release properties.
There are biogradable polymer resins which possibly companies should consider rather than a plastic based polymer resin.
We don’t use Osmocote and use the natural cation/anion exchange characteristics of soils and aged composts to do a similar job to added fertilisers. Soil surfaces are principally cationic (positively charged) and aged composts both cationic and anionic (positive and negatively charged). The only nutrient which can be challenging is phosphorus in high sesquioxide (rusty) soils where the phosphorus is bound up quickly by the soil making it unavailable for plant growth. Slow release fertiliser can partially overcome this effect.
From the manufacturer’s site of what the permeable coating is made of “* Scotts Osmocote® is a controlled release fertiliser that consists of prills (small beads) of high-quality fertiliser encased in a permeable and biodegradable soy extract coating”. No mention of plastic balls, I can find no credible evidence that they are plastic coated or have plastic balls at their centre as some have opined in the extract of the google search you quote. Maybe someone took the mention of “beads” to mean plastic balls when it was just a means to describe what a “prill” means.
Definitions of Prill
What does prill mean? A small, beadlike pellet. (noun)
prill/ (prɪl) /
verb (tr) to convert (a material) into a granular free-flowing form
The Material Safety Data Sheets (MSDS) for Osmocote® does not disclose the coating makeup, but as it may be and very likely is Trade Sensitive this would not be unusual. This may help you decide:
Thanks. I have spoken to many gardeners on this, and all agree that the pellets don’t “biodegrade” but lie around on top of the soil (as well as looking ugly). I would be interested in hearing if any gardeners have a different experience.
Thanks. All i can say is that my experience is confirmed by many other gardeners and that if it is made of a "biodegradable soy extract coating” then it takes quite a few years to “biodegrade”.
I would think that it might take some time to degrade fully, I would not want a product that has a long shelf life to prematurely lose it’s effectiveness as a long term delayed release pellet before or shortly after I had applied it. If it is expected to effectively control release for some 6 months then to ensure this, the coating would need to ensure it’s effectiveness for several years of storage and use.
Have you contacted the manufacturers to explain your issues and try to get some clarity about whether hydro-carbon based plastics are used and if it is biodegradable what time frame might be expected for it to breakdown and what conditions might slow down or speed up the breakdown process? They may be very willing to provide this type of feedback without compromising their Intellectual Property.
Biodegrading will occur with different times depending on the conditions the material is exposed to. Usually for it to biodegrade, it will requires moisture, air, microbes and the right temperature. On the surface of a potting mix/soil, it will be deficient in moisture (it will be mostly dry and subject to wetting and drying cycles) and microbes making the processes prolonged. This is why they will be seen on the surface for some time after the fertiliser may have disappeared.
That’s consistent with my observation of potting mix when the slow release products are mixed through. When repotting after 12+ months any mixed in are part shells, or weak and crumbling.
Thanks. It is my experience (and that of others that I have spoken to) is that they last a lot longer than 12 months… several years at least. Also, as i mentioned before there are other products, such as Troforte which i am now using, doesn’t leave behind ugly yellow beads and is "Australian Made microbe coated and mineral enriched fertiliser. It contains select suite of beneficial soil microbes " So why use Osmocote?
That is a different outcome you seek to your original ask ie you asked that it should be banned and that it should be destocked. Your original post asserted that it contained plastic (assumption here from your post that it was a hydrocarbon plastic), yet beyond casual association there is no actual proof of that claim and the manufacturer advises publicly that it is a biodegradable compound made from a renewable resource.
If the product does contain plastic for barrier purposes or for binding then sure it should be discontinued or sternly discouraged. Have you raised these concerns with the manufacturer? If so, what was their response?
Why use Osmocote? Often it may be because it suits the user, and no I don’t use it. I agree that people should be made aware of alternatives and a post that advises people of alternatives is not unwelcome, so Thank you for advising of the one you now use. As to user preference of one or another perhaps they like the colour of the prills from the Scott’s products or maybe they aren’t aware of the other choices, perhaps they don’t like the alternatives or they prefer the Osmocote over the others. There are a few reasons people choose one product over another, I like that they have choice as long as they are “responsible” choices.
My apologies for taking so long to reply but i have been busy with the usual covid related issues. Yes I based my request on various searches which said that it contained plastic and my (and many friends) experiences that it takes some years to “biodegrade” and become invisible. Also, as i have noted, there are alternatives that are recommended by some experts, and do not leave a mess of yellow and orange beads. So thank you for your informative comments. I will let you know if I find out any more about the composition of Osmocote.
Save your money by creating your own compost or, if necessary, purchase bagged compost or seek out free municipal compost provided by some Councils. That will provide all the nutrients your plants need. I spread a 2 inch layer of compost over my gardens before I plant each season and plant directly into it. don’t forget to use an organic mulch on top. I use pea straw or sugar cane mulch. The earthworms and soil microbes/ insects will incorporate the compost for you over a short period as well as make the nutrients more “plant available”.
Look into adopting a “no-dig” approach to your gardening. Charles Dowding has excellent Youtube videos on the subject.
Sorry but it isn’t true in general that sort of compost will supply all the nutrients your plants need.
Most families cannot produce enough compostable waste to make compost for more than a rather small garden bed. The big tub of peelings and skins you produce every few days will compost down to half a cup.
Council compost can be available in larger quantities quite cheaply (in one case I know of free to ratepayers) but it more a soil conditioner than a complete feed. It is typically made from urban garden trimmings and is not high in nutrients. It might do if you had a low intensity garden of natives, non-fruit trees and slow growing plants but not for heavy feeders. In some cases what councils call compost is not well rotted at all and would better be called mulch.
If you want to grow annuals, especially vegetables or heavy feeding fruit trees like citrus, to get good results you will have to add other sources of major nutrients and in some cases minor nutrients and trace elements too.
The no-dig approach does help to maintain soil structure but that does not magically create necessary inputs if you don’t add them.
