What is a Compost Starter?

Adam Hill

Compost is made up of the decomposed remnants of organic matter. It is valuable as a fertilizing agent in horticulture and agriculture. Any biodegradable matter will eventually decompose, if left to itself, but it can be useful to speed up the process when making compost for home and garden use. In this case, it can be beneficial to use a compost starter. A compost starter can be a household or manufactured material that speeds up the beginnings of the decomposition of organic matter into compost.

A compost bucket.
A compost bucket.

Many garden centers and garden catalogs carry different types of compost starter. While many of these products are varying and proprietary, they all contain decay-causing microorganisms. Some also contain enzymes, hormones, and other additives to help the decomposing organisms work even faster. Special combinations of ingredients are also available for specific needs. Wood chips, pine needles, and leaves, for example, ordinarily take a long time to decompose on their own, and may be helped along by a specially formulated compost starter.

Earthworms may help facilitate the composting process by aerating and providing nutrients to the soil.
Earthworms may help facilitate the composting process by aerating and providing nutrients to the soil.

A compost starter need not be a manufactured mix of ingredients, however. High-quality garden or woodland soil as well as other natural substances can also be added to compost heaps to speed decomposition, because these already contain a high concentration of microorganisms. In fact, early historical records relating to gardening tell us that the ancient Babylonians used the blood of camels and other animals to activate compost.

A similar material called blood meal is sometimes used today as a compost starter. This material is derived from blood collected at slaughterhouses, which is then dried and packaged. It is a very dark red, powdery substance which is nearly odorless. However, while its odor is inoffensive to us, it is repellent to small animals like woodchucks and rabbits. In light of this fact, some gardeners use it as a fertilizer for small green plants, because as it nourishes, it drives away animals that would eat these plants as they sprout.

The main goal of using any compost starter is to provide an environment that is rich in nitrogen and protein, in order to support the growth of microorganisms. Finished compost can actually work well as a compost starter, in the same way that bread starters work. Finished compost contains the nutrients and organisms necessary for decomposition to take place, because it has already has taken place there. Once compost has completed the process of decomposition, it is nearly indistinguishable from other soil.

Compost can be used as a valuable fertilizing agent in gardens.
Compost can be used as a valuable fertilizing agent in gardens.

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Discussion Comments


Does anyone know the science behind why blood helps with the decomposition process? Obviously there is something behind it since the Babylonians used camel blood and we are still using blood meal today.

Does the blood somehow start to grow the specific bacteria that are used in decomposition? Perhaps the blood also already has the bacteria that are needed. That is why using old compost or soil helps speed the process.

Are there any other ways to speed the composting process without adding soil or using commercial products?


Has anyone here ever tried using a rotating compost bin with a compost starter? Right now, I turn my home compost pile by hand, but I have seen the rotating bins advertised, and I thought maybe it would be more effective.

I have a lot of pine needles in my yard, and like the article mentions, I have found that they decompose very slowly without a starter. I am not sure how the compost starters work. I just want to make sure that it would not damage the bin material. Thanks for the help.


I have been thinking about starting a compost pile for a few months. I noticed that I throw away a lot of food scraps and other things that would easily decompose. I do some gardening, but I have several friends that garden and could use the compost.

If I start a compost pile, should I use compost starter, or will it be fine without it? For anyone that has used it, what are the best brands? Most of my material will be food scraps and lawn clippings. I was also wondering, though, can I put things like paper in with other compost, or is that a bad idea?

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