I understand that a lot of people recommend, or even say its neccesary to sterlize or buy sterile seed starting medium for starting vegetable seedlings . I heard some even go as far as sterilize prebought "sterile" mixs a second time. The same people cringe at the thought of using compost, or garden soil for starting seedlings.

Two different issues with quite a bit of difference between them. Sterilizing seed starting mix, especially when it is already sterilized, is just a total waste of time. But buying and using sterile seed starting mix - which 90% of the market products are - is well worth it.

Using compost and/or garden soil are NOT recommended for a number of different reasons and sterility is only one of those reasons. This issue is frequently discussed in great detail over on the Growing from Seed forum here.

What established plants and even older transplants can tolerate in nature is a different world from what newly germinated seedlings can tolerate or thrive in.

We grow and sell vegetable and flower transplants in our greenhouse for sale and wouldn't consider using anything but one of the better quality seed starting mixes for germination and early growth. The cost is just too high otherwise.

But do your own comparison study and see which works best for you.

Dave

"It's only important if you can't afford to lose the plants."

So essentially you're saying it is necessary to sterilize the seedling medium or you are going to lose plants? How many plants would you lose, say sterile vs compost?

But why is it neccesary? Why don't people worry when they sow seeds in garden soil, chalk filled with bacteria and fungus? I rarely observe seeds sowed outside die like some indoor seedlings. So why can you throw a seed in soil outside and it be a success, but when you take that same sool and put it indoors it is a complete failure?

"What established plants and even older transplants can tolerate in nature is a different world from what newly germinated seedlings can tolerate or thrive in."

I hear you. But, im not talking about established plants. I am talking about sowing seed in the garden vs inside. For example, everyone sows beets, carrots, corn outside without a problem. So why cant we do the same thing inside? If anything, i would think you would have greater chance of success i doors, being able to control the environment. Spring is normally wet and all the sowed seed outside, in the soaking wet mud, seems to pretty decent..

Once I saw some tiny bugs. Then I put the rest of my mix in the freezer for couple of days. Because it had perlite I did not want to bake it. After What I did, never see anymore bugs.

Camomile tea is said to prevent bugs too. This is only an indoor problem. If I was going to germinate in cold frame, I wouldn't worry about it.

I have never done sterilizing seeds.

Like Dave, I would not use anything else but a fresh bag of seed starting mix for seedlings started indoors that will stay in containers for a long time. You do not want fungal or bacterial growth in moist, closely confined quarters until the plants are big enough to fend for themselves. I switch to live, bioactive potting soil as the seedlings are potted up into larger containers and hardened off outdoors.

Seedlings grown in open soil can attract beneficial microorganisms that help protect them from problems by releasing root substances, but container-grown seedlings lack this important natural resource. You cut your risk of diseased seedlings drastically by using clean seed-starting mix. To call it sterile would be an exaggeration, however.

I agree with Natures_Nature, in part.

The problem with indoor germination is often caused by TOO much water and NO air circulation. Molds easily grow on the wet top when there is no air circulation. Mold, fungus, insects often can grow and multiply in WET and stagnant air condition. I do not have a fan(yet) but i water my seedlings from bottom, let it drain and then put them back in dry tray. Also I cover the top with things like small pine barks or perlite. So that there is no moisture on the top to invite problems.

Agree with the others. The conditions for starting seeds inside and starting them outside are so very different that they aren't even comparable.

Just the simple act of growing in containers outside is vastly different than growing in the ground, even if the container is directly next to the plant you have growing in the ground. Containers themselves need different soils than what you find naturally. Can you start seeds in containers outside? Yes. Does container soil need to be sterile? No. But that's because the conditions outside are different than inside.

When you try to start seeds indoors in containers, you are giving fungus and disease the perfect environment to wreak havoc. The potting mix tends to stay wet longer when inside, the temperatures are relatively stable, there is little air movement (unless created artificially or by having an open window), and the light inside isn't as strong. Not only are these the perfect conditions for fungus and disease but these conditions also makes for weaker and/or more tender plants. And weaker/tender plants are more susceptible to having disease and fungus problems. Therefore use of a sterile, soilless potting mix is recommended so that you can at least try to avoid some problems.

Rodney

I am talking about sowing seed in the garden vs inside.

Two totally different environments and like already mentioned - not comparable. There are just too many variables in a static environment vs. a stagnant one.

For example, the fungus disease damp-off is the most common cause of seedling death. It can develop in the garden or indoors but is 5x more common indoors. Why? Outdoors the weather environment goes through cycles of warm/cool. light/dark, wet/dry, and air is constantly circulating. So the life of fungus cycles normally too. It has less of a chance to latch on and develop to the point of affecting the seedling unless the weather is unusually bad.

Indoors the environment is stagnant and it is usually one where fungus can thrive.

The fungus that causes damp-off is primarily in the soil. Begin with clean mix indoors and you cut your odds of it developing by at least 1/2.

So essentially you're saying it is necessary to sterilize the seedling medium or you are going to lose plants? How many plants would you lose, say sterile vs compost?

Seed starting mix is already sterile so you don't have to sterilize it. How many plants would you lose? Roughly, 50 to 100%.

Ad fungus diseases is only one issue. There are also the problems of germination rates, poor drainage, root compaction, nutrient imbalances, O2 vs. CO2, etc.

We are all convinced based on experience so as I said above do your own small study of comparison. It is a great learning experience.

Dave

PS: I may be wrong but I get the feeling you have compost and want to use it? If so keep in mind that compost requires an active soil micro-herd to convert it to available nutrients the plants can use. Works great in the ground but in a container you don't have those active microbes.

Starting seeds in compost can be done with some success but it is much more difficult and requires very closely monitored and adjusted environmental controls.

"Once I saw some tiny bugs. Then I put the rest of my mix in the freezer for couple of days. Because it had perlite I did not want to bake it. After What I did, never see anymore bugs."

Anytime I hear something tiny bug, I think of aphids. They completely sucked the life out of my seedlings last year!

Very interesting, thats for your post... Did you notice any difference between the "buggy mix" and the "frozen mix", in terms of the health of your seedlings? Or, did you simply discard the planting medium with bugs in it right away, and find a solution, which you found yours to be freezing the medium...

"You do not want fungal or bacterial growth in moist, closely confined quarters until the plants are big enough to fend for themselves."

Sounds logical, a confined space that is cut off from natural defenders(beneficial microbs) could definitely become a breeding ground for pathogens. Thanks for posting.

"Seedlings grown in open soil can attract beneficial microorganisms that help protect them from problems by releasing root substances, but container-grown seedlings lack this important natural resource"

Great post! But, why wouldn't a plant inside be able to produce the same substances, given they have the same beneficial microbs?

"The problem with indoor germination is often caused by TOO much water and NO air circulation. Molds easily grow on the wet top when there is no air circulation. Mold, fungus, insects often can grow and multiply in WET and stagnant air condition. "

You hit the nail on the head! It doesnt matter what you are using, without proper care, you are going to get some pathogens. That's almost the foundation of germinating/vegging plants, provide the right environment. The focus should be on providing the least favorable environment for pathogens, while simultaneously trying to provide the most favorable environment for your seedlings.

Been there, done that, got the t-shirt. I was asked to grow organic tomato seedlings in bulk last year. We are talking 20,000 plants. Now, I am fairly competent at growing tomatoes, I've done it for quite a few years on a small commercial basis. But I had never grown entirely organic seedlings. I started out by mixing peat moss with worm castings, perlite, and vermiculite. I started the seed and watched them emerge and then keel over in droves. Over 5000 seedlings lost at one whack.

So I tried again, this time in pure worm castings. Same results, another 3000 seedlings whacked. This time, I knew the problem was with the worm castings.

I don't give up easily, so I mixed peat moss with worm castings and put it in a very large pan with a small amount of water and I steam sterilized the mix for about 40 minutes until it reached a temperature of 212 degrees. I let it cool and put it into clean trays and started seed. The resulting seedlings were the healthiest and best I've ever grown.

There is a very important reason why commercial seed start mixes are sterilized. Rhizoctonia and Phytothora are two of those reasons.

"When you try to start seeds indoors in containers, you are giving fungus and disease the perfect environment to wreak havoc. The potting mix tends to stay wet longer when inside, the temperatures are relatively stable, there is little air movement (unless created artificially or by having an open window), and the light inside isn't as strong. Not only are these the perfect conditions for fungus and disease but these conditions also makes for weaker and/or more tender plants. And weaker/tender plants are more susceptible to having disease and fungus problems. Therefore use of a sterile, soilless potting mix is recommended so that you can at least try to avoid some problems."

It almost seems as if the real problem is trying to grow inside with sufficient equipment.

"PS: I may be wrong but I get the feeling you have compost and want to use it? If so keep in mind that compost requires an active soil micro-herd to convert it to available nutrients the plants can use. Works great in the ground but in a container you don't have those active microbes"

Thanks for your post Dave. Ok so let me explain myself... No, i am not crazy nor hardheaded enough to disregard what you guys are telling me and go straight for my "compost". No, i dont have compost on hand now, buts its easy to make, and is probably the closest thing to seed starting mix. I trully want to use whatever brings me the most succes. But here's the key word - self sufficient. I do not want to rely on needing a business's seed starting mix. I want to find a way to start seeds, just as succesfully as pre bought mixs, but With materials you can get in my yard.

"So I tried again, this time in pure worm castings. Same results, another 3000 seedlings whacked. This time, I knew the problem was with the worm castings."

I understand that you sterlized the mix and found it to be a success, so there is a good chance is was some kind of pathogen in the castings, but perhaps it was from poor growing conditions? Did you have fans circulating air,etc? Im almost wondering if growing conditions is the main reason, and people just blame their medium? Maybe im just optimistic..

My mileage seems to be a bit different. I buy a t combination potting/seed starting mix ...like Fert-i-lome or similar. I don'y know how sterlized it is or isn't.

I take seedlings outdoors as soon as sprouted whenever I can to a sheltered place in the sun and only a gentle breeze if any.
I have no problems. I am retired and can manage them according to the weather. They are hardened in from the get-go and are very healthy.

"But here's the key word - self sufficient. I do not want to rely on needing a business's seed starting mix. I want to find a way to start seeds, just as succesfully as pre bought mixs, but With materials you can get in my yard."

I'm with you 100% on this, and this is one of those topics that I've looked at over and over and over and basically disliked the popular answer every time. I've never understood how all the homesteaders and sustainability folks jive relying on store-bought seed starting mix with their broader philosophy.

Now, I don't use seed starting mix. I do use old potting soil, mixed with a little bit of well aged compost, and then just grow out my seedlings. I have fatalities, but nowhere near 50%. Last year my seedling-death rate (from all causes) was somewhere in the neighbourhood of 2%. I grow out all my starts for a nearly-one-quarter-acre vegetable garden and all the flower beds in a 130-year-old farmhouse cellar; I watch those little buggers like a hawk. I run a fan over my seedlings, and I spray with peroxide and water if I suspect any funny business, and I sprinkle with cinnamon, etc. and it seems to work. I grow very healthy seedlings that go on to be very healthy plants.

I would love to know what it would take to make your own seed starting mixture. We have a 400+ acre peat bog across the road, more compost than I will use for the rest of my life (thank you, cows), and a great big wood burning oven that's used for boiling sap for maple syrup. I think, with all that, I should be able to make seed starting mixture that's more or less sterilized. I just haven't tried it yet.

The way I do it now works for me, and what I get grows more blooms/fruit/vegetables than we can possibly use, but it would be interesting, nonetheless, to see if it could be improved by sterilization. Sometimes I worry that I've just been lucky so far.

And, of course, it would make me feel like I'm doing it right, based on what all the experts say you have to do in order to be successful.

But here's the key word - self sufficient. I do not want to rely on needing a business's seed starting mix. I want to find a way to start seeds, just as successfully as pre-made mixes, but With materials you can get in my yard.

Then my question would be how many plants is the goal? If you have lots of room to work with, plenty of plant lights, ideal environmental controls and you don't mind wasting lots of seeds - say plant 50 seeds and hope to get 5 good plants - that would be possible. But most of us prefer 1 seed = 1 plant or at most 3 seeds = 1 plant.

Do you have a good pH meter? One where you can make your own mix (main ingredient is peat which is likely NOT in your yard) and keep the pH balanced? Do you know the pH of your water? Most is highly alkaline.

Point is there are recipes available for making your own mix from peat, vermiculite or perlite (which you won't have either), hydrolized lime, and sand. But most find when they buy all the components to mix their own, get it pH balanced, and then sterilize it, the costs surpass just buying a bag of ready-made.

Assuming your ultimate goal is in ground gardening rather than containers (which is a whole other ballgame) then the most cost effective method is to buy seed starting mix to germinate in and then use your own mix of whatever to transplant them into once true leaves develop.

One can start literally 100's of seedlings with 1 small bag of sterile seed starting mix.

Have you read through all the FAQs and discussions about this over on the Growing from Seed forum here? Also, is there a local greenhouse you can visit to study their seed-starting operation?

Dave

Madhacktress,

I see we have a lot in common. So you basically use old potting soil, with compost, and careful maintenance with hydrogen peroxide,etc? Sounds a little better than relying your food for the season on some inert matter out of a bag.. But it still is in that realm..

I can assure you I will do my best to find a way to start successful seedlings, year after year, without the need for any of that..

So guys what are my options? Taking lose and using compost? Sterilizing compost? I know there has to be some successful gardeners(around 75% seedlings live) that uses compost, or some other similar medium..

Madhacktress,

I see we have a lot in common. So you basically use old potting soil, with compost, and careful maintenance with hydrogen peroxide,etc? Sounds a little better than relying your food for the season on some inert matter out of a bag.. But it still is in that realm..

I can assure you I will do my best to find a way to start successful seedlings, year after year, without the need for any of that..

So guys what are my options? Taking lose and using compost? Sterilizing compost? I know there has to be some successful gardeners(around 75% seedlings live) that uses compost, or some other similar medium..

"It almost seems as if the real problem is trying to grow inside with sufficient equipment."

Exactly. Growing inside is completely unnatural. Unless you have money to buy expensive set-ups and can simulate outdoor conditions, which most people don't, you can't compare outdoors vs. indoors. That's why we should take every precaution we can when trying to grow inside.

I will say that when I pot up seedlings from a cell pack to individual pots, I use a mix of 2/3 seed starting mix to 1/3 compost. (in the cell pack I use 100% seed starting mix) I only do this with strong, healthy little plants and haven't had a problem yet. And my fingers are crossed that I won't have a problem in the future.

MadHacktress- "Now, I don't use seed starting mix. I do use old potting soil, mixed with a little bit of well aged compost, and then just grow out my seedlings. I have fatalities, but nowhere near 50%. Last year my seedling-death rate (from all causes) was somewhere in the neighbourhood of 2%"..."I watch those little buggers like a hawk. I run a fan over my seedlings, and I spray with peroxide and water if I suspect any funny business, and I sprinkle with cinnamon, etc. and it seems to work. I grow very healthy seedlings that go on to be very healthy plants."

You're taking corrective measures by using peroxide at the first sign of problems. That's why you're successful. Your diligence allows you to disregard others recommendations. If you're careful you can afford to do so.

Rodney

" I know there has to be some successful gardeners(around 75% seedlings live) that uses compost, or some other similar medium.."

After all, seed starting mixtures only recently came to market, probably not even a century ago. Before seed starting mixtures, what did people use? I understand that there's a reason seed mix came to market, because whatever we were doing prior to the seed mix probably wasn't working as well. I completely understand that part.. But there has to be a better alternative.. Any ideas?

I have a book that was originally printed in 1944 (I have the 8th edition printed in 1976) called "Gardening Indoors With House Plants" by Raymond P. Poincelot. In the book he talks about pasteurizing (not sterilizing) homemade potting soil. Here's the excerpt from the book:

"If you suspect you have troublesome soil insects or plant pathogens or just want peace of mind, it is a relatively simple matter to pasteurize soil. Place it in a tray and moisten it with water until it is thoroughly wet for uniform heat conduction. Preheat your oven to the desired temperature. A temperature of 130*F for 25 minutes will kill soil insects, while a temperature of 180*F for 30 minutes will kill plant disease pathogens or microorganisms."..."Incidentally I've never encountered any odor problem while heating the soil as long as it is thoroughly wet."

Rodney

Better alternative? No.

Alternative? Yes.

Seed starting mediums are preferred by many for the same reason other technology advances are preferred.

There's not much on the line except a smaller chance of success. People used seed starting mixes without peat/coir/perlite/vermiculite/etc long ago, but risk and plant care issues were elevated.

You can start seeds in whatever you want, but for most home gardeners it comes down to...is spending $2-$10 on a bag(s) of sterile seed starting mix worth the enhanced chance of having healthy seedlings 4-8 weeks after planting? For me, it's closer to $2-$4 a year because I grow my seedlings to 3 true leaves in 4-6 pack cells...I don't use a lot of soil starting mix.

To me, it ranks up there with washing out my seed starting containers with 90% water/10% bleach every year...sure, I could pass on it, but it's not worth the risk when it's so easy to do as a preventative.

Thanks again nc, very helpful..

Although, you said one thing: "There's not much on the line except a smaller chance of success."

Ok we wouldn't be having this conversation if it was just a smaller chance.. From what everyone says, its a huge chance! The person a few post up lost thousands of seedlings from this.. I can go for a few plants dead, i cant go with nearly all my plants dieing and not having food on the table. So now, i question really how much better is a "sterile" mix than say, compost? Is the difference just a few seedlings, or nearly all your seedlings? Of course, it depends..

nc-crn: "To me, it ranks up there with washing out my seed starting containers with 90% water/10% bleach every year...sure, I could pass on it, but it's not worth the risk when it's so easy to do as a preventative."

This is something I do, even though I always kind of wonder what the point is when I don't bother to sterilize the seed starting mixture. But it just seems to make good sense.

The soil that I use for seed starting mixture, whether it matters or not, I'm not sure, is old used up soil from houseplants. I don't keep soil from plants that grew outside, nor do I keep soil from plants that have died or were battling any sorts of nasties. I just keep the old soil from when the plants are potted up or have their soil changed out. It's soil that was originally compost brought in from outdoors, but has been inside for at least a year if not years.

Rodney: "You're taking corrective measures by using peroxide at the first sign of problems. That's why you're successful. Your diligence allows you to disregard others recommendations. If you're careful you can afford to do so."

Yeah, that certainly true. I don't ever feel like I'm fighting to keep them alive, however. If I did that would certainly make me change my tune (I mourn the loss of plants). But then again I don't mind having to spritz a little here and there to keep the them healthy; if they grew with zero interaction that would be rather boring for me.

Natures_Nature, a lot of what you've said I have heard come out of my own mouth! I've had the same thoughts about "if they sprout in it in the garden, why wouldn't they sprout in it in the house?" And same thing with "what did they do 'back then'?" I'm the seventh generation to grow in this ground, and I'm sure that none of those who came before me used seed starting mix. But I think maybe the most important part of all of this came in your last reply: "Of course, it depends".

Which I think is exactly the point. If everything else is perfect, airflow, light, moisture, etc. then sterile soil probably matters a great deal less than it does if some or all of those things are less optimal. And, of course, attention and intervention at the first sign of trouble also helps. And when you're growing 20,000 seedlings that becomes difficult; but there's an economy of scale in this, too. I can grow my 800-ish seedlings and give them a fair amount of regular attention and nip any troubles in the bud.

I've also been growing in the same gardens in the same soil for nearly all of my 30-mumble years. And I've been doing it basically this way for 10 years. So I have some experience (although there were a few years when I stole the light from my fish tank and rotated it around flats in 8-hour shifts... thank goodness those days are past!). My technique is no longer an experiment.

Once you get on to what works for you, well, it will work for you.

I still say I don't understand how some of the experts can jive their zeal against uber-big businesses having their fingers in seed companies, promote heirlooms and sustainability, talk about preparedness and self-sufficiency in the "just-in-case-it-all-comes-crashing-down" world and at the same time proclaim that nothing other than store-bought seed starting mix will work. At all. Ever.

Mad:

Exactly... Ok, so I'm thinking outside the box.. You guys know how some germinate seeds on a moist paper towel? How about starting them similar to that then transfer them to the infested compost or whatever? Thats right i cant do that option either, i cant fathom the fact i am in need of paper towels from a corporation(just joking)... No, really, in all serious, would this work? The idea is letting the seed sprout and even grow on the paper towel(kind of like hydroponics) then when they are ready, let thhem put on their gloves and fight the bacteria?

Natures nature, Do you even grow your own plants? Or do you go to a store and purchase your seedlings?

I grow 100,000 seedlings each year. I run a small commercial business producing and selling plants. I start seedlings under grow lights in early spring and in my greenhouse under natural light during late spring and summer. Starting under grow lights is NOT the problem. Starting indoors is NOT the problem. Temperature and/or air circulation is NOT the problem. The problem plain and simple is fungi in the soil that kill seedlings graveyard dead. Starting seed on a paper towel and transferring to soil mix won't avoid the problem, the paper towel is sterile, but when you put the seed into the contaminated soil mix, fungi will kill them within a few weeks. If you want to know for sure, get some seed, get some compost or worm castings or whatever suits your fancy and start your seed. You will soon have your own t-shirt to prove you know what you are advising.

Fungi are not the only possible problem when producing seedlings. One year I had an outbreak of fungus gnats. They lay eggs in the soil mix which hatch into larvae that devour seeds and seedlings. It took nearly a month to wipe them out so I could get normal seedling growth.

For those who want a home made seed start mix, here is one I settled on as meeting my needs.

3.5 cubic feet of peat moss (25 gallons)
3.5 cubic feet of worm castings (25 gallons)
2 cubic feet of perlite (about 14 gallons)
1 pint of dolomite lime (do not use any more, lime can be very bad for seedlings)
Dampen the mix with a couple of gallons of water

Get a 55 gallon steel drum and a turkey fryer. Cut the top out of the drum and put 3 bricks into the bottom of the drum, then place the cut sheet of metal from the top on the bricks. Put an inch of water in the bottom of the drum. Sit the drum on the lit turkey fryer and fill up the drum with the above mix. Put a lid on and turn up the heat until the water is boiling then turn it down to a good steamy simmer for an hour. This will sterilize the mix. Let it cool and start filling seed trays. This mix is ideal for tomatoes, peppers, onions, brassicas, and most other vegetable transplants. It is NOT a good mix for growing blueberries or any other acid loving plants, though if you leave out the lime, it would work. You will have to fertilize with compost tea or bird guano tea to get optimal growth, the above mix doesn't contain enough nitrogen to grow a full size seedling but it does have enough to get them to the 2 or 3 inch tall stage.

If you make your own compost, consider switching to vermicomposting. It is a better final product for garden use and you get plenty of worms to go fishing. This guy sells both worms and worm castings. http://www.greengregs.com/ There are plenty of other worm farms around that a google search will find.

For those who wonder how seedlings were started before (put your chosen olden year here), they were grown in cold frames with a mix of hot horse manure, cold horse manure, and good garden soil. A trench was dug three feet deep and a foot of fresh horse manure was placed in it so the heat of composting would warm the cold frame. Garden soil was mixed 3 to 1 with well decomposed horse manure and filled in on top of the fresh manure until it was within a foot of the top. Seed were planted on top and covered with a shallow layer of the soil/manure mix. A frame was built around the trench and window sashes were placed on top. In effect, they made a mini-greenhouse with bottom heat. I have a 1910 copy of The Garden Library - Vegetable Garden which has these instructions though in a great deal more detail.

This post was edited by fusion_power on Sat, Dec 7, 13 at 10:23

We are just rehashing the same questions over and over. All the issues first posed have been answered several times. Lots of opinions but all with the proviso of unknown variables and providing ideal environments. So why continue to hash them? To change minds?

Those with experience have learned from their own experiences and so know what works for them. And they have shared them with you. You can accept or reject them or pick and choose from them. But folks aren't going to change what they have proven to work time and again.

Is there always room for improvement? Sure. But outside the box approaches and regressing to old methods we 'think' they might have used isn't the way to improve it.

There are many more aspects to successful seedling growing then just the soil mix used. So since you say you don't have much experience at it, why not first try the proven methods to improve your odds. Then you can modify them as you wish as you gain experience? Otherwise you are just setting yourself up for failure.

Dave

PS: Just in case you didn't realize it your replies to other's posts can all be combined into one reply post. Makes it much easier for the reader to track the conversation. It isn't necessary to make individual posts.

Fusion:

Informative post! I am actually just starting to get into gardening! I started eating plants for health, then you realize these plants at the store might not be as healthy as people claim, so I starting foraging.. But sometimes you want something other than bitter greens(dont get me wrong, i get fruit as well,but only a short season. So here i am, gardening.

So i can either start shoveling horse manure in the cold frame or go back to foraging.. Forget this, I'm going to home depot to buy some seed starting mix that the "experts" recommend.. Or, maybe walmart.. Man, do i have jokes or what?

All joking aside..

So the closest thing I can get to seed starting mix is probably sterilized compost??

So the closest thing I can get to seed starting mix is probably sterilized compost??

No. Sterilized compost is nothing like seed starting mix. As explained at least a couple of times above seed starting mix is composed of peat from peat bogs. The amount varies but is usually 60-80%. To that either perlite or vermiculite and a little lime is added. Then some sort of nutrient supplement is added to some, but not all, of the mixes.

Some of the newer mixes are made from coconut coir rather than or in addition to the peat but other additives are the same.

Keep in mind when researching them that 1) all are already sterilized when manufactured and 2) use only those labeled "mix" not "soil".

Dave

""Seedlings grown in open soil can attract beneficial microorganisms that help protect them from problems by releasing root substances, but container-grown seedlings lack this important natural resource"
Great post! But, why wouldn't a plant inside be able to produce the same substances, given they have the same beneficial microbs?""

Regarding this...Plants get to work on this task right away, but we humans understand very little about how it works. So, the best thing we know to do (so far) is to provide a root environment free of known troublemakers.

An excellent gardener I know takes a different approach that might interest you. He gathers handfuls of "duff" -- the one and two-year-old layers of rotting leaves on the forest floor -- and uses it like peat moss in his soil mixes, including those used for seed starting. It's about as far from sterile as you can get, but the proof is in Frank's results, which are admirable year after year.

I make my own seed starting mix:
AND THIS IS HOW I DO IT.

== ~ 60% peat moss (OR finely screened bark fine)
== ~ 20% perlite
== ~ 20% vermiculite
These are just rough proportions. 5% more or less is not important, to me.

Put about 1/2" layer of pine bark at the bottom(of 3.5" square pot), fill to 3/4" with the mixture and plant my seeds in it. BTW , I germinate my seeds then transfer them to the pots(Small scale jobs). You may do it directly.
I have a mister filled with water, and keep the seeds(already germinated ) moist until they grow cotyledon leaves. Afterward I bottom water them. When the stems are about 1 inch or so, I fill around them with bark fines, TOO KEEP THE TOP DRY. You can use perlite instead too. This way no mold, no fungi growth on top.
NEVER FILL THE POT WITH STARTING MIX UP TO THE RIM.

If in case I encounter bugs, spray with camomile tea solution(diluted) . With one tea bag of camomile you can make over a quart of solution, maybe more.

Lots of good comments & advice already given (notably by Fusion, Digdirt & Plantatus) to which I concur. I'll just try to add my 2 c's on a few points already discussed.

"Sterilized compost is nothing like seed starting mix. As explained at least a couple of times above seed starting mix is composed of peat from peat bogs. The amount varies but is usually 60-80%. To that either perlite or vermiculite and a little lime is added. Then some sort of nutrient supplement is added to some, but not all, of the mixes."

A commercial mix has been sold here whose main component is shredded bark; I've used it for several years, and am happy with the results. It would offer a good alternative for those who consider the use of peat to be the destruction of a non-renewable resource.

"I still say I don't understand how some of the experts can jive their zeal against uber-big businesses having their fingers in seed companies, promote heirlooms and sustainability, talk about preparedness and self-sufficiency in the "just-in-case-it-all-comes-crashing-down" world and at the same time proclaim that nothing other than store-bought seed starting mix will work. At all. Ever."

As I've read through this thread, that wasn't what I heard. What has been said is that you should start with a sterile medium... and provided that you sterilize a fertile soil or mix, the results can even be better than the sterile (but nutritionally weak) seed starting mixes sold commercially. Really, all of the other discussions - indoor versus outdoor, etc. - take a back seat to that issue. Fusion's experience with his own mix was a great example of what can be accomplished, and leaves the door open for a great deal of experimentation.

Those who grow their crops in subsistence levels - and rely on them for sustenance - can't afford the chance of a complete loss before the plants even get in the ground. You try to minimize the risk to the greatest degree possible... and at present, the sterile mixes sold commercially are a very reliable way to do so. If those were not available, however, I think the people in question (self among them) would find alternatives - some of which have already been mentioned. My methods (in my climate) would likely differ from those in warmer zones.

And if "it-all-comes-crashing-down", there would not only be no starter mix, but no power for lights or bottom heat. At that point, IMO, seed starting becomes something of a non-issue... I would be less concerned with forcing hot-weather plants (of relatively low nutritional value) to grow in my climate, and more concerned with growing nutrient-dense grains & root crops that don't require coddling to produce.

"This is something I do [sterilizing containers], even though I always kind of wonder what the point is when I don't bother to sterilize the seed starting mixture. But it just seems to make good sense."

Even when you start with sterile soil & containers, contamination can (and often does) occur through airborne spores; fans & dusty or damp locations can increase the chances of initial infection. When this occurs, there would likely only be a few plants affected, unless the container were enclosed (I recommend against those "mini-greenhouse" flats for that reason, they are fungus breeding grounds). But if you were to then start the next year with some containers already infected, it would be giving the pathogens a chance to develop & spread more quickly, and the losses would greater.

I would add that the sterility of soil & container can be rendered moot, if the water used to dampen them - and the fingers & tools used during planting - are not also sterile. I use rubber gloves when planting, and RO filtered water or boiled rain water for seed starting. If I add an organic fertilizer to the water (which increases germination in old seed) I boil it before use. Once the plants are growing (and have their first true leaf) the sterility of water is probably less important.

" I run a fan over my seedlings, and I spray with peroxide and water if I suspect any funny business, and I sprinkle with cinnamon, etc. and it seems to work. I grow very healthy seedlings that go on to be very healthy plants."

I like the peroxide idea. It might be even more effective if it were used preventively (before symptoms occur) rather than correctively... it would be interesting to test that idea, and determine the dosage & periodicity that are most effective. It's worth mentioning, though, that peroxide also does not fit into a self-sustained philosophy. There might be other solutions (perhaps herbal teas) that would offer an alternative.

For what its worth, I think Madhacktress & the original poster are on the right track philosophically... the vast majority of gardeners do not use sustainable methods for seed starting. If the economy were to go sour, there could be increased interest in this topic.

I wouldn't think of starting seeds in non-sterile medium. Although I'm sure that some people have succeeded without using sterile medium, why not sterilize it? Now, that's easy to say, because doing such sterilization is trivial, as noted above. The idea of paying money for sterile planting medium seems weird, unless you're using truckloads of it. Moisten the medium lightly, put it in layers less than a few inches thick, and stick it in the oven at 400F for an hour. You can probably fit a quarter of a yard at a time in your oven this way, if you have the right trays. Microwaving should work too, though the length of time will depend on the volume and the power. Freezing will kill bugs, but there are many microbes that will not perish at freezing temps.

You can wash your hands, wear a face mask (no sneezes!), wrap the planted bed in plastic to keep the dust off of it, sterilize the water you use, and hose down all your guests with antiseptic, but by far the greatest risk is what is already in the soil. We're not talking hospital sterility here.

As to the structure of the medium, good advice above.

My thing is to not unduly fuss with fungal and bacteria free environments, but to take things out into God's free air and sunshine.

I don't raise thousands of starter plants nor extra fussy ones, so I have had excellent results with what I do.

Let me amend what I said above. Although I haven't been that careful about it myself, I understand from various cooperative extensions that it is best not to get the mix too hot, as high heat can produce toxins (perhaps from mineral degradation?) The recommendation is to use a 250F oven, and get the mix to 180F for at least half an hour.

Of course, the main thing you're trying to kill are the fungal spores that lead to damping off (which only happens to seedlings). By the way, best to put this mix in sterile containers -- either pots that have been baked, or containers rinsed briefly with diluted bleach.

Daninthedirt: I'm guessing you have never tried cooking soil. I did many years ago in a 9 by 13 cake pan (which holds only about one gallon), which I baked at 200 for a half hour. The odors produced were horrendous. Also a quarter of a cubic yard is about 7 cubic feet or 40-50 gallons. No way could I fit that in my oven.

I bake my soil to sterilize it each year. Creek shoal sediment (mostly clean sand with a range of grain sizes) and peat moss. No smell whatsoever. I have an outdoor oven, so I don't really care. Might be smart to cook a small quantity before you stink up your house, though. I suspect some rogue organics could make life miserable.

Good question about how to cheaply sterilize without an oven, though. I suspect if you dump a few cups of bleach in a pail full of mix, stir well and cover it tightly for a week or two, you'd knock everything out. Need to dry it all out before you planted, though.

But you're right. I miscalculated. A few large trays of soil would be about a tenth of a yard. Could do a good fraction of a yard in a long afternoon, if you're well organized, however!

It is important to use decent seed starting medium, fresh and not reused. But baking is an awful stinky mess that has no benefit. If you have sifted compost or something else similar you want to use to save cost, use that when transplanting things like tomatoes to bigger containers but always use good fresh seed starting mix for seeds. No need to sterilize. I use the one with the mychhorize in it or whatever it is called. I am tired and can't remember.

Well, if we're talking about baking compost, get out the clothespins and put them on your nose! Ick. Don't do that.

I have grown hundreds of pepper, tomato and other vegetables per year for the better part of 50 years, using just soil from my garden with a little perlite and dried moss mixed in. I have never any sort of issue with losing plants, or even with any significant number of weeds to deal with. Call it dumb luck.