Compost Accelerator – Are They Necessary?

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Robert Pavlis

If you are interested in making compost you will soon run into products called compost boosters, or compost starters. What are they? Are they necessary? Do they work?

Compost booster, compost starter

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Compost Boosters – what are they?

The terms compost booster and compost starter are both used for a product that is designed to activate your compost pile, and make it compost faster. There does not seem to be a standard definition for these products and the terms are mostly used interchangeably.

What are they? Even that is confusing. Some products don’t say anything about what’s in the box. They just tell you they are good for compost and that you should buy them. Some products are essentially a nitrogen source ie a fertilizer.  Others are microbe inoculants. And some are a mixture of a nitrogen source and microbes. In a few cases they also have added enzymes which will be discussed in a separate posting, but in short enzymes don’t add anything useful to your compost.

The funny thing about these products is that they all promise the same benefits for your compost and garden. How can products that are vastly different produce the same results? Could it be that they don’t really do very much?

Microbe Science for Gardeners Book, by Robert Pavlis

 Adding Nitrogen to Compost

Why add nitrogen to compost? You have probably heard about using the right amount of browns and greens when making compost. Why is this important? Compost is made when microbes digest the organic matter. In order for microbes to grow and be very productive, they need a certain amount of nitrogen in their diet. If you use the right amount of greens and browns, so that the carbon to nitrogen ratio is in the range of 30 to 1, the microbes will have enough nitrogen from the greens and they will grow well and make compost quickly.

If you have too much nitrogen, your compost file will smell. If you have too little nitrogen, the process of making compost will be much slower because the microbes do not have enough nitrogen. In this case adding nitrogen will speed up the process by making the microbes grow better.

The most economical way to add nitrogen is with common fertilizer or fresh manure. Use a handful of 48-0-0 or a formulation with a high nitrogen number. If a compost boosters contains nitrogen, it will also work, but it is a more expensive option.

If you use a mixture of browns and greens you probably don’t need any nitrogen or compost booster. Too bad that none of the manufacturers of these products are honest enough to tell you this fact!

 Adding Microbes to Compost

Compost is made by microbes, so it seems to make sense to add them to a new compost pile.

The material you put into a compost pile is mostly plant material; old leaves, stems, flowers etc. All of this stuff is covered with billions of microbes. The soil and air is also full of microbes. You don’t need to add any more.

If you feel the need to add microbes, add a bit of soil to the mix. Soil is guaranteed to have the right microbes for making compost since this is exactly what they do naturally in soil—they degrade plant material.

There is no logical reason to buy microbes for the compost pile. What is worse is that you just might be importing foreign organisms into your soil. The microbes in a compost starter are microbes selected by the company making them. There is no guarantee these are native microbes in your area. For the same reason that you should be careful about adding non-native plants to your garden, it is also a bad idea to add non-native microbes.

If you feel the need to add microbes to the compost pile, just add a shovel full of soil.

Being Environmentally Friendly

Most people who compost are trying to be environmentally friendly. They want to make their soil better. They want to garden organically. They want to reuse waste plant material. These are all good things.

As part of their goal to be environmentally friendly, they now buy products like compost starters. These are not environmentally friendly products even if the label says they are. Every time you buy something in a package, it is not environmentally friendly. The packaging is not organic.  The trucking of the package uses oil. The manufacturing process uses natural resources that could be better spent on products we actually need.

Don’t buy products you do not need. Compost booster and compost starter are products you do not need.

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Robert Pavlis

I have been gardening my whole life and have a science background. Besides writing and speaking about gardening, I own and operate a 6 acre private garden called Aspen Grove Gardens which now has over 3,000 perennials, grasses, shrubs and trees. Yes--I am a plantaholic!

11 thoughts on “Compost Accelerator – Are They Necessary?”

  1. Thank you. I’m a very amateur gardener, and we have a compost bin. I’m comparing opinions from non-sponsored sites and trying to educate myself to be a better gardener. This was helpful.

  2. I have been doing compost for many years. I have been doing it in an easy way. I collected kitchen green stuff in several buckets. When they turned rotten I buried them in my garden beds. I just started wanting to do a better job and ran into your article. Thank you so much. I will not buy any compost starter. Still I will do better job to compost.

  3. I live in Lincolnshire UK. I’ve recently acquired an electric shredder. I thought I’d need some compost starter to deal with the shredded material -mostly hedge trimmings as I have 60-70 metres approx of hawthorn and privet. I then saw your item (even though its been online for a few years)and realise my misconception. So no futile expense and a few hints about how to get a good composting result.
    Thank you.

  4. I loved the issues posed by Carol Clark, as well, of course , by your basic analysis, Robert — always so sensible. Many years ago, when having imported from local sources a huge tonnage of autumn leaves, I occasionally sprinkled on urea, hoping to feed the decomposing microbes, since I was trying to make garden soil. This appeared to work effectively. Even leaves deeply buried and compressed by my machine decomposed (anaerobically?) rapidly. But a further question I would ask is whether human urine, in “reasonable” amounts added to primarily brown compost piles would speed decomposition?

    • Yes – its only problem is that it contains a fair amount of sodium which can be toxic to plants. The key is “reasonable” amounts.

  5. Thanks for the compost starter piece. I have been wanting to compost and am now living in a place where I can and am getting started. I sort of knew intuitively that compost starter was probably not necessary – but it was good to read why. Looking forward to my gardening being enhanced

  6. As part of a project while studying mycology, my son collected compost from our kitchen composter to identify the fungi in the sample. His classmates all had samples taken from their accomodations, or public lawns and parks. The group was astounded to see the extensive number of foreign organisms in the compost sample. Apparently, our imported fruit and vegetable scraps had contributed this array of foreign organisms. I’ve always mixed the kitchen compost material with a much larger volume of garden compost, so am unable to discern if those foreign microbes have been deleterious to the garden or the general surroundings. Actually, if there is an environmental impact from foreign organisms, what is to be done with the compost produced by civic waste management operations or zoos which doubtless are replete with foreign material?

    • Very interesting question. I don’t think there is much we can do. We have been unable to control infectious diseases, or large pest organisms from getting around the globe. Controlling microbes will be impossible, on a practicable level.

      I don’t think this problem has been studied very much. It could be a big problem of the future, or it could be a non-issue. I expect it will be a problem, and one we have to just live with. Once soil is contaminated, it will be impossible to decontaminate.


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