Compost activators, accelerators, starters, boosters, inoculators – do you need to pay for them?

Apr 25, 2023 | Gardening tips

First, let’s define what terms like activators and accelerators mean. This is not easy because most people, including commercial manufacturers of such products, use these terms interchangeably and do not define what they mean. Manufacturers do not detail the actual ingredients in the products they are flogging, making it even more difficult.


Activators, starters and inoculators are the same things. An activator starts the composting process. It initiates a reaction. Activation happens when organic material and microbes are mixed together. Inoculators are simply a mix of microbes (fungi and bacteria) that are already present on the material put into the compost heap.

Do you need to buy activators?

No – just throw a handful of soil into your compost heap but remember that microbes already cover everything in your heap so even a handful of soil is not really necessary. What is necessary is moisture, so water layers as you build your compost pile and add water regularly as organic material breaks down.


Accelerators and boosters are the same thing. An accelerator speeds up the composting process. It does this through the addition of nitrogen in the form of grass clippings, fresh manure, blood and bone etc, and raises the temperature of the heap.

Do you need to buy an accelerator?

No – just added nitrogen.

Should I add lime?

No – lime will raise the pH of the compost heap. This is not necessary because the heap will correct its own pH as it decomposes. In the early stages, the compost becomes acidic and this acidity kills off pathogens. If you lime and therefore alkalise your heap, this process won’t happen and you will be left with pathogens you don’t want or need.

Should I add fertiliser?

No – Microbes need nitrogen. If you have too much carbon (brown material) just add more grass clippings or other nitrogen sources. Microbes do not need trace elements in fertiliser – only the nitrogen – but why add fertiliser when you can add green material for free?

Should I add worms?

No – worms fry in the heat of a compost heap that is working well. They will disappear into the subsoil when this happens and come back later when they are safe.

In an attempt to make money, manufacturers offer gardeners many unnecessary products, trading on gardeners’ confusion and ignorance. When it comes to composting all you need to know is that if you mix organic material and microbes (and this happens automatically because microbes are everywhere and on every surface), with sufficient nitrogen, water and oxygen, your heap will heat up and produce free nutrient-rich compost very quickly. If you can mow everything you add, the process will be even faster. A hot compost at 60C can take as little as 16 days while a cold compost at 10C can take 18 months.


2 good references that are worth reading in full are the following written by Tony Callaghan from SoilFixer in the UK and by Robert Pavlis from Canada from Garden