Is there a particular type of mildew that you're concerned about? Overall, without chemicals, the single biggest factor is going to be moisture for most mildew-type fungi and the like. Other less pleasant growths also tend to occur where there's no air (anaerobic conditions) - so avoid plastic bags, is my guess, or at least something that breathes more.

A separate point: if it's living soil, there are going to be growths in it of some kind in time, so whatever you can do to limit the time it's just sitting in bags will help. Note I'm not claiming any special knowledge of packaging soil ). Good luck.

I would avoid plastic if at all possible. Otherwise, make sure the bag has some air penetration. All the best bagged mixes available here (including the custom C&S soil sold by a local grower/purveyor that I use exclusively for that purpose) have numerous tiny perforations that allow air to enter (and moisture to escape) but are far too tiny to allow the soil mix to filter out.

And make sure it is kept out of the weather!! Even if kept under cover outdoors, the mix will absorb moisture from the air and where there is moisture and a "living" soil (not sure how necessary that is for any sort of container soil but that's another discussion :-)), there will inevitably be some mold/fungal development. Far less so in a cool but very dry location like inside a warehouse.

Cloth bags will allow areation of the mix and less chance for mildew. If it occurs though, the aeration will allow most of the offensive odor to disperse.

Additionally, I think a neat cloth bag with perhaps a distinctive logo screened onto it would add a real touch of class and uniqueness to your product.

Is there something bad about mildew? In a biologically beneficial environment, mildew happens, and it's not going to hurt anyone. All soil has fungi in it, even though it might not be conspicuous. That is, at least for powdery mildew, treating the plants with fungicide is a lot smarter than treating the soil. But if visible mildew offends you then, as noted, air penetration is helpful. If in plastic, just perforate it with some holes. Paper bags seem unrealistic unless the mix is incredibly dry. Paper will just get dissolved by a moist mix.

Has mildew been an issue for you? I can't say I've ever seen plastic bags of soil with conspicuous mildew, and I can't believe they sterilize the stuff before they put it in those bags.

..."if visible mildew offends you." I think the entire point is that visible mildew or funky smells (whether caused by mildew or not) will not be acceptable to consumers and/or the store. That's more or less the only definition of 'bad' that matters in this context. I understand this is for use in containers - likely indoors - so I wouldn't want to risk using soil in that state indoors, either. I'd happily take it for free and use it in my yard, though.

What about drying the soil out?

Wow, thank you.

Full of great ideas. If you will bare with me, I have a few questions about some of your ideas.

I will try to respond to all, but not necessarily in order.

Bob, some of the microbes will bot be able to survive a complete dry soil. Also soil is slightly moist when you buy it, because very dry soil repels water. Unless the person has a good understanding of soil it can be tricky. Not only does it repel water, but once it starts to take it up. It will quickly become soggy.

Daninthedirt, First I would like to say, I love the name Dan-in-the-dirt. That's a good one. Most soil is not sterilized before bagging. Mixes for seeds and "indoor" soil, are the only two normally sterilized. See below response to your question.

armourded hit it the nail on the head. Neither the customer of garden centre will be please with the smell mildew. Most people can not identify the smells in soil, but most people have encountered mildew smell. It will immediately turn people off. Also, where mildew grows, also grows black mold.

It occurred to me if the soil is quality, the other beneficial organism, would most likely inhibit the growth of one single organism. I have noticed, soil I store in similar containers do not develop the smell. I also notice the soil I added the mildew smell lava & pumice, smelled of mildew at first, but since is not longer having the overwhelming soil. There must be microbes that eat mildew.

gardengal48, I agree, I would like to avoid plastic if I have a choice. I also agree with the holes in the bag. If anyone has ever used those Ziploc Produce Bags, you will know they are full of tiny holes. They do keep produce fresher for a very long time. The first time I used one, I put in a head of romaine lettuce. I forgot about it, until cleaning out the door, a month or more later. That lettuce looked as good as it did the day I put it in those bags. It lets air out, but not back in.

Something like that is an option, but still plastic.

Even if people can not open the soil in the store, I want them to be able to see the difference of quality soil. Another advantage of plastic. That is why I was looking at strong kraft bags with windows.

I have decided I will replace any soil bags left on the store shelf longer than 2 months. I can always use the soil for myself, as well ensuring the freshness of the product. I worry the mycorrhizal fungi will quickly loose viability. After discovering a strain of beneficial organism as bio-fungicide or mycorrhizal, companies invest quite in figuring out how to make them stable enough in a dry or liquid form. This is why some never come in a powder form. I am sure adding it soil with any bit of moisture will make an impact. I have thought of having the mycorrhizal in a separate bag in the big bag. I think replacing in 2 months is the best option.

If all goes well, that will not be a problem most of the year. Especially if I only bring as much as they need. Unlike them having to store a pallet of soil

Geoforce think you and I are on the same wave length. Last night I spent time looking for flour sacks. It would allow me to print the name and logo on the bag. It would not give people the choice of seeing it. Even so, I think a cloth bag would stand out. People will notice a soil brand that does not use plastic. Instead uses bags that can be washed an reused by the customer. Reusing bags, means they see the name many times, not just a bag in the shed.

Until I can afford to print on the bags, I can affix a tag to the bag.

I have a small cotton shopping bag, I use for vegetables, I am going to test this idea.

Thank you all. It has been great reading the feedback. You are amazing. I am still open to other ideas. The cotton may not work.

Cheers & Smiles

Maybe a window it not needed. It is hard to see the benefit of the soil by the eye, since so much is dark, like the lava rock. You can feel the difference better. In the picture it just looks like typical soil, even though it is not.

(FYI: Zero coir. THE FOLLOWING IS MY CURRENT OPINION. I RESPECT ANYONE HAVING DIFFERENT THOUGHTS I do not feel it brings an benefit, as well as no proof of being more environmentally friendly. Especially taking into account the poverty the farmers and workers are living. It is actually not a waste byproduct. Farmers use to use it to yearly condition the soil of the coconut fields. Now they have to bring in fertilizers. It takes chemicals to break down coir into the parts we can grow plants in. Horticultural uses less than 1% of the peat harvested. I do not use just peat. (Less than 30% of this is peat. If packed it gets down to 18%)

Again thank you.

Thanks Armoured.

The good thing about reusable bag, you have advertising that may last for year with info printed on them

Finding hard to find reputable printing company that carries these type of bags. None will print on one I buy somewhere else.

Might look into local company offering embroidery . I think for the time being all I can do is add a tag to the bags. There is not advertisibg, but that can come later.

I'm testing a cotton bag with soil at home now and so far no problems.

I need need help with adding wetting agent. Will start new thread

We use sandbags. They are reasonably priced, and breathable, which keeps the soil from growing strange things. They only downfalls are that labels do not stick to them, and because they have tie at the top, it's hard to get the top completely sealed. We have to keep bags upright to avoid small amounts of soil from leaking out. Might be worth looking into.....