No. If the compost you are adding contains the right food for worms they will arrive naturally. If it does not, any worms you buy and add will die for lack of food, or leave for better conditions. If you are adding your own home made compost it would probably contain some worms anyway.

Worms (earthworms) like to live in clay. They will move into the compost of their own accord if it suits, and incorporate it into the soil.

As floral says, you don't need to add worms. They come. All you have to do is provide the right conditions.

A clay soil holds its structure very well. This is important to a worm because it (the worm) can make its way through clay without getting squashed or injured if a human walks over the soil.

Wet clay cannot hold its structure. If heavy machinery moves over it, it will affect its structure. It will become compacted.

Do you have a clay-based soil? If you do, that's good.

@tete_a_tete Yes I have a soil test. What part is of interest to you?

If you buy worms you will get one of the species which specialises in processing fresh organic matter and which appear naturally in compost and manure heaps. They are not soil dwellers and will not live in clay or any other soil. The soil dwellers are different and are species of earth worm. Neither type will stick around if conditions do not suit them. And both types will appear naturally if conditions are right.

“Earthworms differ from compost worms because they thrive in different conditions. An earthworm prefers to consume soil, burrow deep into the ground, and is a solitary creature. Compost worms prefer to eat rotting organic matter and live nearer the surface in groups.” https://helpmecompost.com/home-composting/implementation/can-i-use-earthworms-for-composting/ 

@floral_uk z.8/9 SW UK That was very helpful, and I did not realize that there were different classes of worms that specialize in clay soil versus compost. I am sure my clay soil has worms, and I am sure my compost does not because it came from a wholesale supplier who probably does some level of sterilization. I have never seen a compost worm in the product they deliver to me by the yard.

So I guess my original question could be reworded: is there any value in buying compost worms to introduce them to my layer of compost on the ground, to have them continue to add organic material into that surface layer of compost?

Earth worms do not specialise in clay soils in particular. You’ll find them in all sorts of soil.

You would see compost worms if you made your own. They need uncomposted materials so, no, there is no point in adding them to the stuff you buy. It doesn’t contain the raw food they need.

Compost is not sterilized. It would defeat its entire purpose!

@gardengal48 (PNW Z8/9) All I know for sure is that the compost I receive never has worms in it, so someone either removed them or the process they use has no worms in it.

Worms will appear in fresh compost all on their own. They breakdown yard and kitchen waste in its earliest or freshest stages. Once they have depleted that source, they leave the remains to be digested and more fully composted by smaller soil organisms and microorganisms and move off themselves to a newer, fresher supply.

Wen you receive bagged or bulk commercial compost, all the organic matter that would support larger soil life has already been processed and all that remains are the creatures too small for you to see. So yes, no worms in "finished" compost.

@gardengal48 (PNW Z8/9) I got some additional compost education here, and thank you.

Most compost is sterilized. Otherwise you would get lots of weed seeds. It has to be heated to kill the seeds. Not sure if it kills all the bacteria too, but even if it does, the bacteria would quickly come back.

Baloney!! An active and well managed compost pile heats up sufficiently all by itself to kill off any weed seeds and harmful pathogens. It is NOT sterilized!! I don't know of any home composters that sterilize their compost - why would they? - and yet they still manage to generate a product that is mostly weed free.

The nonsense that gets repeated on these forums is really quite startling. It might be worthwhile for some members to actually visit a commercial composting operation to see how it is done.

The compost pile heats up and this kills off the weed seeds. And maybe a lot of bacteria too. How is that not sterilized? You seem to be hung up on how it's sterilized. Not on if it's sterilized or not.

And you seem to misunderstand the difference between a "sterilized" compost, implying something that has been artificially treated to eliminate all microorganisms, and a carefully processed natural compost that goes through expected temperature changes without eliminating all the necessary bacteria and fungi that makes it a valuable garden amendment.

Despite its appearance, compost is not "sterilized" or dead.....it is very much alive!!

You might want to read up on the composting process to see what the difference between the two situations are before you start making these unsubstantiated claims.

Pasturized temps can kill off the seeds and much bacteria, and most home hot compost piles can get that hot. Range of around 140-160ish degrees or so. Sterilization temps kill off everything, and most home hot compost piles don't get quite that hot, getting up over 180 degrees. It can help create an anaerobic enviroment that kills good microbes. While anaerobic composting can have it's place, regular hot pile composting isn't that place. Pasturization works for good compost, sterilization usually isn't necessary or desired.

You don't usually see worms in hot pile compost because the piles get too hot for the worms to stick around. Their heat limits max out around 80, well below hot pile temps. Worms are more often found in cold compost piles because the temps stay more in their range. They aren't found in worm compost because the compost is harvested and the worms left to do their job making more. Mushroom compost does not usually have mushrooms in it- the mushroom have already been harvested and the compost is the spent medium.

Without taking any sides here, I can say as someone who works extensively with food fermentation that a temperature of 140F is certainly going to kill the majority of bacteria, after as little as 45 minutes.

It is also worth mentioning that seeds generally are built to survive temperature extremes better than bacteria, which lack a hardened shell and reduced metabolic need during harsh temperatures.

If the pile is getting to 140F, I think it would be fair to say that a lot of things in that pile are dying, both seeds and bacteria.

The above said, as someone who works with bacterial genera a lot, I can tell you that the old saying "everything is everywhere, all the time" is definitely true about bacteria. Any sterilizing of that pile is instantly undone when the temperature comes down, and common bacteria would immediately recolonize the compost. You cannot keep bacteria out of organic material that still has any value for the bacteria.

Most areas in the US have garden waste recycling and the garbage company runs a composting operation. This is sold as "garden waste compost" by wholesalers. Are these products typically using hot composting, or do they ever use cold composting?

Research thermophiles. These are heat loving microorganisms, primarily bacteria, that thrive at temps above 140F and are one of the key components of a hot or commercial composting operation. Weed seeds are effectively killed off at 125-130F, far below temps that would affect thermophiles.

Additionally, if a compost should get too hot - above 180F - the process simply shuts down, the pile cools and then it starts all over again.

ETA " Are these products typically using hot composting, or do they ever use cold composting? "

Hot composting. The point is to get the product processed and out of the facility as quickly as possible. Cold composting takes far too long. They would be overwhelmed by the quantity of waste to be processed.

@gardengal48 (PNW Z8/9) Great point on thermophilic bacteria. These bacteria can survive temperatures north of 200F. But my question would be are thermophilic bacteria really the bacteria that end up in the final delivered compost, after it is applied to the garden? I suspect that these bacteria reduce their numbers, and the beneficial garden bacteria occupy the new niche. The bottom line is this supports your idea that the hot composting process sterilized the seeds, but it's not the bacteria in the delivered compost that necessarily end up being the bacteria that use the soil ongoing.

In your opinion, does cold composting have any advantages - other than removing the need to manage the compost pile - for a home gardener trying to make their own compost?

" But my question would be are thermophilic bacteria really the bacteria that end up in the final delivered compost, after it is applied to the garden? "

No. They only survive at those temperatures so once the compost is relatively finished and cools down, they are no longer present. Their work is done. Cooler temp bacteria and fungi take over.

I still balk at using the term "sterilized" when dealing with compost. Killing off weed seeds and pathogens is part of a normal active composting process but it is a far cry from sterilization!!

Years ago I read that cold compost produces a product better able to suppress diseases in the soil than hot compost. I probably read that in my father's 1950s Better Homes and Gardens gardening book, so I hesitate to say it's true.

Composting doesn't sterilize the seeds, although I understand what you mean. The seeds are actually "cooked" in a hot compost pile.

The only reason I attempt hot piles is to get an end product as quickly as possible, but I'm perfectly happy to use rough, cold compost---as a mulch---if I need it.

Regarding compost worms. I got them merely by composting. The red wrigglers or whatever that they sell for worm bins are the same worm species that will come to your compost pile on their own. They eat your compost and poop it out. I'd rather have earthworms if I had to choose one or the other. Earthworms poop and are better soil aerators.

When I was around three, my father did something inexplicable that my brother was able to explain to me years later. I remember my dad one night with a big box of nightcrawlers---huge nightcrawlers. He walked around our front lawn tossing the worms on the ground. The next odd memory is from the next morning, the rest of us waking to my father yelling and running arond the front yard flapping a dish towel. The lawn was covered with robins pulling nightcrawlers out of the ground. My father had purchased the worms expressly to "work" his lawn. He thought they'd all be burrowed by morning, but they weren't. We did battle with a huge flock of robins that day. I always wonder, when I encounter some massive worm here, if its ancestor knew my dad.

I find cold composting still needs managing, just sometimes less and usually different management than hot composting. Cages are zero turnover for me. They end up being 3' tall raised beds full of worms, good soil, and has less weeding or seeds as standard garden beds. And the benefit of being almost critter-proof and easy to pick from. Chop and drop lets me utilize the weeds to draw up nutes and then I leave them on the soil they came from- I tend to edible weeds in the beds so I can eat them and use them for compost. Sheet composting with green and brown materials through the year builds up organic materals and muches the beds. Ferments, teas, and waters tend to be cold and is something that some folks like to get into. Usually used as fertilizers and drenches rather than a growing medium.

Sterilizing is something done to dental instruments and the like.

Pasteurising is sometimes done to potting soil. We used to pasteurise (steam) the potting mix that was used to pot indoor plants. After treatment it still contained good bacteria but was free from disease or weed seeds.

BTW, westes, I never mentioned a soil test. I did ask if you have a clay soil

@tete_a_tete I have clay loam soil that drains about four inches every three hours.

In the composting industry, sterilized means no viable seeds. It has nothing to do with bacteria. All compost is full of bacteria. It would be impossible to deliver compost with no bacteria.

" In the composting industry, sterilized means no viable seeds. "

No it doesn't. Show me one website that uses this terminology. In fact, the term "sterilized" just does not enter the conversation when discussing a composting operation, commercial or otherwise. It has a precise meaning that does not come into play with a fully natural process.

Some serious backpedaling going on here. 🥴

i used to gather them off the driveway and sidewalk during and after rains.. and put them on the compost pile.. and i further presumed.. they worked their way straight down the pile and back into mother earth.. processing the pile as they went...

ken

The worms on the driveway would not have been composting worms. They would have worked their way back down to ground level but would not have bothered with the compost material. Not to their taste.

westes, you can harvest worm castings in a stacked worm bin by stopping their food. The worms will migrate to the areas where the feedstock is still being provided, leaving you pure worm castings to harvest. The same process happens with compost. Quit contributing to the compost pile and the (feedstock-dependent) worms will head out, not stay and starve.

Here's a google search for "steamed mushroom compost". It;s not for a single web site but the google results of the search. Seems that it's common for mushroom growers to steam the compost. From my memory they grow two mushroom crops in any batch of mushroom compost It's steamed twice so I would guess it has something to do with getting only the one variety of mushroom they want to produce.

They wouldn't want anything to grow in there other than mushrooms. They want a pasteurized soil. So they steam it.

We used to steam the potting mix that we used to pot indoor plants. I think the length of time needed was 30 minutes. We had a special soil trolley for the purpose. After steaming, the soil trolley would be driven into the potting shed, and someone (sometimes myself) would wrap plastic around my boots, climb up, and shovel the mix into the area that housed this mix.

In later years, our indoor plants went by the way-side. The glasshouses were put to use to house 'outdoor' plants. Anywhere a batch of potted plants could be put, they were put. Sometimes it caused great inefficiency, but only to us workers, so it didn't matter.