Compost activators, and whether your heap needs one

What a compost activator actually is

A compost activator, which gets sold as a compost starter as well, is nitrogen and a load of microbes in a bag, and the idea is that you tip some through a heap that has gone quiet and it fires back up. That is a real product doing a real job, and it works when nitrogen or microbes are genuinely the thing your heap is missing. In a backyard heap that has been going a while, they usually are not.

Your heap already has the workforce in it. The bacteria and the fungi are already in the garden soil and on everything you throw in, and the worms find their own way, and a shovel of your own dirt or a couple of handfuls out of the last finished batch carries more living microbes into a new heap than most people expect.

The 4 things that actually stall a heap

When somebody brings me a photo of a heap that has sat there doing nothing for 2 months, it is nearly always one of these, and none of them are fixed by a bag.

• It is too dry. Compost should feel like a wrung out sponge, and a heap that crumbles dry in your hand has stopped working because the microbes have nothing to live in.
• It is too wet. Sodden and smelly means there is no air getting through, and the bugs that take over in those conditions are the slow smelly ones rather than the fast ones.
• It is nearly all brown. A heap built out of dry leaves and straw and shredded cardboard has plenty of carbon and almost no nitrogen, so it sits there looking like a heap of dry leaves for a very long time.
• The pieces are too big. A whole brassica stem or a branch takes months because there is so little surface for anything to work on, and chopping the same material up is free.

What to reach for before you buy an activator

If the heap is short of nitrogen, which is the only one of those 4 an activator fixes, you have probably got something that will do the job already.

• Grass clippings straight off the mower, which are about as green as green material gets.
• Aged manure, and aged is the word that matters, because fresh will burn anything you put the finished compost on.
• Used coffee grounds, which go in the green side of the ledger even though they are brown to look at.
• A shovel of garden soil, or a couple of handfuls of finished compost, which is the microbe half of what is in the bag.
• A pelletised manure, which is the tidy version of the manure heap and comes in a bag you can actually lift.

When a bagged one does earn its place

There are a couple of spots where I would not argue with you. A brand new heap in a brand new garden, on ground that has been under lawn or under concrete and has nothing much living in it, gets going faster with a hand up. And a heap that is almost entirely dry leaves, which is what a lot of them look like once the deciduous stuff comes down, needs nitrogen from somewhere, so a bag of pellets or a bagged activator is a perfectly sensible way to get it.

The rest of the time the heap is telling you what it wants, and you can read about carbon to nitrogen ratios for an hour and still not be sure, or you can bring a handful of it in and we will have a look at it together and you will know in about 2 minutes. That is the bit a bag cannot do for you.

Shop related products

• Brunnings Garden Compost with Seaweed 25L. Finished compost, and a couple of handfuls through a new heap is the cheapest starter going.
• Neutrog Rapid Raiser 20kg. Pelletised manure, for the heap that is all dry leaves and short of nitrogen.
• Naturally Good Cow Manure 25L. Aged manure by the bag, for anyone without animals of their own.
• Martins Organic Sugar Cane Bale 11kg. Brown material by the bale, for a heap that has gone sodden and needs drying out.

Did you know we also stock the Brunnings Ultimate Dig It In Compost 30L, Nincompoop 25L, pea straw and lucerne bales, and the garden forks that do the turning. They are not all on the website, so give us a ring on (08) 8536 4333 to check what is on the shelf.

The bagged soil, the manures, the mulches and the seed raising mix all live together in the garden centre, and the online range is over in garden products if you would rather have a look first.

Big bags are heavy and we deliver, so if you are in Strathalbyn that is $5 and the wider run is $10, on Tuesdays and Thursdays. The whole lot is on the local delivery page.

Read next

• How to turn compacted soil without wrecking your back
• What is the cardboard weed barrier method?
• How to prepare your soil for a winter vegetable garden

I am still the one who forgets to turn it, so I have made my peace with the slow version.

Cheers,
Candeece