Seed Starting Medium?

What do you use for a seed starting medium? Why? Im just curious.

Last year when I was too broke to buy anything I had OK results from wandering out into our hardwood forest with a bucket and a screen. Shoveled up leaf litter and the decomposed matter under downed trees and a bunch of wood so rotten it would pass through 1/4" hardware cloth. Found some particularly rich humus and leaf mold in the crotch of a huge bifurcated sycamore tree where leaves and water had been collecting and rotting for many years. A bit of soil found its way in to the mix as well, mostly from when I would dig my shovel too deeply into the forest floor.

It worked rather well except that of course it was not sterile; I had volunteer germinations from the forest floor seed bank that I had to distinguish from my own seedlings.

Dan, did you notice any nitrogen deficiency with using the decomposed wood or did it seem fine?
I've often thought of using the stuff I find inside hollowed out trees.

1/2" screen and a pile of old, old wood chips, pine straw, compost ...
and no, I did not sterilize it in the microwave or boil it or anything the like

The best seed starting mix I ever had was 50% mushroom compost and 40% my clay soil and 10% sand (usually granite). Mushroom compost is magical. It was the straight stuff from a mushroom growing operation. A bagged product that has it might work if it DOES NOT include "Forest products" which is bark, wood, etc.

I keep a bag of potting soil around that does not contain "forest products" and add 25% to 50% granite sand, or any sand that is not beach sand with salt. I get the seeds to germinate, then always water with compost tea. I don't make really formal compost tea, I don't aerate it with a pump. I just make tea in a bucket with it, and strain off the liquid.

I don't even use any compost that has wood products, bark, chips, bits that still look like wood in the garden. It just absorbs the nitrogen and the roots of the plants don't get it. Completely broken down wood, however, does well around mature plants and perennials.

Akiva Silver wrote:Dan, did you notice any nitrogen deficiency with using the decomposed wood or did it seem fine?
I've often thought of using the stuff I find inside hollowed out trees.

It seemed fine. But I was only using this for seedlings that got transplanted into rougher soil fairly young.

The wood I used was enormously decomposed. I don't know how long it takes a fallen oak tree to crumble into a powder you can pass through quarter-inch hardware cloth, but that's how long this stuff had been laying on the forest floor. I would guess "decades" at a minimum. My thinking is that most of the nitrogen demand that occurs during woody decomposition had already been satisfied.

i generally add some of the native soil, screened, to a bag soil/seed starting bag soil. right now i am working through the end of a bag of coconut coir, its soooo nice! but usually out of my budget.

i also add a lot of river sand. sometimes i add the sand right to the bottom of the pot, put a handful or more if its a medium/larger pot or add rocks to the bottom, then a handful of the native screened soil, then the top part is bag soil, with some sand thrown in or not depending. often i recycle the bag soil...from pots that didnt come up, and whatever else i can get together, and make big batches. so its always different.

its always nice to get a fresh bag of seed starting soil, but its not something i want to spend the money on, but it does drastically improve my seed starting. sometimes if i happen to have a lot of it, i will use that straight, and for tiny pots, usually adding at least a bit of sand because it works well and is free for the digging.

for one theres bugs in native soil, which isnt that bad on larger older plants, but is very bad for young seedlings. especially if i take them inside, then it just turns into bugs taking over the seed starting area, not good! sterilizing it is such a bother.
for two the native soil...if i add too much, gets weird funky, not ideal for young seedlings. like either stiff or funky, or has bunch of tiny wood pieces in it that get weird/funky bad. well its hard to describe, and cause it depends on that batch, but the seedlings struggle in it, as opposed to the nice fluffy seed starting soil.

straight sand may work ok for some things, theres no nutrients in it so its not good for long term, but for certain things its very good. or mostly sand, little bit of native soil/bag soil works very well too.

I often use cheap compost WITHOUT any fertilizer mixed with vermiculite and a little bit of sand. I also use the substrate from my potted plants when I change it, because it's supposed to be poor after one year of "feeding" a plant.
I used to use seed starting mix but it's much too rich for the seedlings, and once I put them into the soil, they feel depressed.
With poor substrate, I think the seedlings do better when they are transplanted.
I've heard that seeds have everything to get the seedling going for 6 to 8 weeks, so it depends on when you're going to transplant the seedling.
My $0.02.

I usually buy a bale of organic seed starting mix that has microorganisms in it. I transplant up when the first true leaves come into a potting mix that I make with my horsemaniure in sawdust compost ,course sand and either peat or coconut coir .I do not turn my compost but it is completely broked down full of living organisms . I water seedlings with compost tea or nettle tea as well as liquid seaweed and fish .

I use a mix of 2 parts potting soil from the bag, one part peat/coir, and one part perlite for small seeds like lettuce, spinach, onions, peppers, tomatoes etc. I screen this through a sheet of quarter inch hardware cloth (no frame needed). I also plant in small sections of plug flats cut down for easy handling. I've tried many things, but this is the most reliable for getting good germination and survival.

For larger seeds such as squash and beans, I'll use used planting mix in larger old pony packs. I also transplant small seedlings ready to move up into pony packs with used mix.

My 100 year old apple trees have been hollowed out by a large wood borer. I read that their castings was the original potting soil so I tried it and it worked very well. The borers are very long lived and get as big as a thumb before they metamorf. I put them in a bucket with the wood they were working on. This reminds me I need to check tomorrow and see how they are doing.
I built my greenhouse over an existing garden soil that was very sandy. It stays mostly dry now as I grow things in the planters. I can sift the sand from the floor and use it for potting mix If my seeds don't germinate I may get something interesting like snapdragons that have persistent tiny seeds. Other volunteers are California poppies, broccoli, bok choy, holly hocks and alpine strawberries.
The neighbor's cow has been getting out and mowing my field for me So I am thinking of trying to make some shredded paper and cow dung pots by molding the with an old muffin tin.

In the most recent podcast, part 3, Paul cautioned against using purchased top soil and other items due to concerns about persistent herbicides. I have used seed starting mixes to start my seeds indoors. If I did not want to buy seed starting mixes, what would I start my seeds in?

You can make a very good seed starting mix made of equal parts of peat, perlite and vermiculite.

I don't know about potential risks of residual persticides in peat though..

i use compost from our garden. it s still mixed with clay soil, so i add some sand and lots of organic material to that compost and let it rot.
it s not perfect by now, because we started with the compost heap that already was there. so theres clay-soil in it and too much coarse, wooden-bits.

i do indoor soil-sprouts alot (peas, barley-grass, wheat-grass and sunflower), so i m practically "seed-starting" all the time. i add organic matter buried in the pots (flowerboxes) for the soil sprouts and some worm-compost which still contains some worms. so the pots keep producing and improving the soil. to prevent mold, i add a very thin layer of sand to the top.
when the trays are harvestet, they go into a flow-through-worm bag.


so you can produce and recycle your own potting soil

I use soil taken from a forest setting (diversity), perlyte, and sheep manure from my sheep, then put it in my cement mixer and tumble it. It mixes well, any clay balls up and is discarded, along with any sticks, roots or other "junk", leaving me with very workable potting soil.

You can mix all this by hand if you do not have a cement mixer, but I suggest just about everyone get one. I use mine more for mixing dirt then I ever do cement. Harbor Freight tells small cheap ones for $100! Not a bad investment.

For over 30 years we've used our garden soil, mixed with perlite (if soil has more clay) or vermiculite (if soil has more sand) and sifted compost. About equal parts. Have never bought potting soil. We do amend our garden's soil with minerals using William Albrecht's formula (cation saturations of 60-70% Ca, 10-20% Mg, 3-5% K, up to 1% Na, depending on soil types). See more at http://www.geopathfinder.com/Soil-Fertility-Nutrition.html

I've been sheet mulching for years with wood chips -- HEAVILY -- particularly among my fruit trees. When I need potting mix, I start first by going out into the citrus orchard, pull back the mulch, and take a couple of big shovelfuls of soil from there. It's usually full of mycelium, nicely aggregated and has a high carbon content. Then I mix it with equal parts sharp sand and well-finished screened compost. I don't buy anything.

It does the trick.

I don't keep buckets of the stuff around, but mix it as needed. I want to use it "fresh" while the fungi and bacteria are still living and active.

when i plant starts into bigger containers, i add some leaves and/or kitchenscraps near them bottom. so i ll save medium. and end up with having more and better medium afterwards. it can be done indoors. i like to add worm compost with worms (earthworms) to the bigger trays/ containers. the worms help aeriating and improving the soil and help processing the leaves/kitchenscraps. they ll propagate there, so the worm-population (worm bag or garden) will be imporved, also.


i work on that system to stay independent of bought pottingsoil/seed-starting-mix for plants in our flat. and for convenient disposal and harvesting of used soil with the worm bag. in our garden we ll have enough finished compost in 1 or 2 years. should be much better than what we found there.

 
Geoff Lawton recommends 2/3 sharp sand - available for free on the inside bends of rivers, and 1/3 sifted, highly diverse, local compost, with a little bit of worm castings if available. He starts most of his seeds in this mix that he makes for free.  I've had great success with it too.  Seeds don't need much except a well drained substrate - sand, and some biology & the nutrient they provide - compost, to get going. Once they sprout, they need more nutrient of course, which is provided mostly by soil critters.

If you make your own compost of local materials, then the microorganisms will be the ones that are adapted to your biome, which will help the plants grow better in the native soil, which should be amended with the same local compost.  It's the same with worm castings/worm juice. With herbaceous plants, you'll want a more bacteria dominated compost, and for woody plants & trees, a more fungal dominated compost.

This is achieved by the ingredients you put into the compost pile - more herbaceous plant matter and less woody material for more bacteria and more woody material for more fungi.   Look up Elaine Ingham's YouTube videos on making compost, she explains it in detail. You can also look into the Berkley Method which Geoff teaches - the fastest method known so far -18 days to finished compost -it is more labor intensive however.  Worm castings are also bacteria dominated and good for herbaceous plants, and are also always at a perfectly neutral  7 pH.  Mother Nature is Damn Good, no?

   My grandpa, whose family were farmers for generations in England, always said "the compost pile is the heart of every farm" and he was right. It's the nexus where "waste" becomes solid gold for the soil, and it closes many of the loops in any biological system. You really can't have closed loops with out the decomposition cycle, whether it happens naturally or in a man made pile - no life without death, that's Nature's way.  

Good Luck!

Dan, you said you had a problem distinguishing your sown seeds from unwanted volunteers.
This is why gardeners love sowing in ROWS. Your stuff grows in straight lines and in unwanted seeds grow everywhere! Follow the lines!!

I've always bought one bag of potting compost for starting my seeds, but last year I did something different. I ran out and had to use garden soil, some home-made compost, a bit of leaf mould and the remains of the bag of potting compost. My seeds came up better than they ever have before

So this year, I'm going to use leafmould, and fine soil from one of my better beds, plus the best compost I have.... mixed about equal parts. Not buying any more potting compost ever again

I've not tried it yet, but leafmould layered with comfrey leaves is meant to make a good base too....

Robert Jordan wrote:Dan, you said you had a problem distinguishing your sown seeds from unwanted volunteers.
This is why gardeners love sowing in ROWS. Your stuff grows in straight lines and in unwanted seeds grow everywhere! Follow the lines!!

Ha!  Very funny.  But like many people, I start my seeds for transplanting in little plastic trays, one seed per cell.  Not a lot of room for rows in a garden bed that size...

I think potting soil sold in bags is not the right medium and it is very different fro potting soil in bulk. We have not all that many decidious trees and thus a lack of leafmould which I preferably use for my own garden. I start seeds in commercial potting mix bought in bulk but use a sieve for the top layer. Probablyt inoculation gwould help.

Someone mentioned sterilizing soil in the microwave or boiling it. Doesn't that leach out all the nutrients?

Colin McGee wrote:Someone mentioned sterilizing soil in the microwave or boiling it. Doesn't that leach out all the nutrients?

I understood the only reason purchased "soil" is sterilized as not to commercially transfer disease or bugs. Anyone else know more than me (which isn't hard since I am a novice gardener).

This year I am going to use my shredded leaf mold compost and sprinkle worm castings on top from our worm farm. As we have no money and are far away from civilization I am hoping for the best. This is also our first year starting our own plants. We cannot plant until about the second week in June. Right now we still have anywhere from 3-6 ft of snow on our land. I got the idea from Mark at I AM ORGANIC GARDENING on YouTube

I've always used ProMixBX or a commercial seed starting mix.  The seed mix is a finer grind than standard potting soil.  You really don't need added/extra nutrients in the seed starting mix.  The seedlings are transplanted into pots/containers very soon after they germinate, or if germinating in the container they will be grown in they can be fertilized at a low dosage when needed.  I use liquid/water soluable fertilizers/nutrients (typically a cold processed seaweed product from the local hydroponics store) for all my transplants usually at 1/8-1/4 strength for the first few times then as the plants get large enough or have to be potted up I will increase the nutrient strength as needed until time to plant them in the garden. At that point they are going into organically amended and mineral balanced soil and will require little else other than some additional nitrogen on crops that require higher N .  

I just moved to a new house so my personal resources are very limited.  Luckily there is a mushroom farm close by that sells an entire pickup load of mushroom compost for $20 and I am having very good luck with equal parts perlite, coconut coir and the compost, it comes out as a very loose starting mix.  It is working well for the seedling starts and as potting soil once my sprouts have true leaves.

For the poster who said they have a hard time sowing seeds in a row because they use plastic trays try moving to larger wooden boxes made from scrap wood mine are 14" x 20" x (3" and 6" Height).  They are large enough to separate the varieties by about an inch and do not collapse catastrophically.  As the sprouts get larger I move the best looking ones to the deeper boxes or to individual pots / solo cups.  Try to keep the roots from bottoming out in your seedling containers, it has a tendency to send many into bloom which slows their growth once out in the garden.  When plants are putting energy into reproduction they stop putting energy into growth.  This is one of the reasons many people prefer to plant directly in the garden for the faster growing plants.

I believe there is no need to sterilize seed raising mix, why should it? Weed seeds can fly in at any time.
And with the mushroom compost: take care. First it can contain a lot of nasties and it can contain a lot of salt. Number one kills you number two the plants.

I agree with your caution of the compost before using any I test on a few broad leaf seadlings like beans which die quickly especially for grazon herbicide which is persistent for years.  It is nice having sources nearby where I can source organic compost and manure from ranchers who grow their own feed.  The mushrooms are certified organic so the compost should not have too many nasties and my plants seem to love it.  Until I can establish my own compost crops I am going to have to rely on others. Trying to get a decent garden year one is difficult, my current soil has been a grass yard for 20 years and is solid compacted clay with very low NPK in soil tests.  I have been bitten in the rear before trusting municipal composted manure which had pesticides in it so I am very careful.

Wow, I am so excited. I love this time of year. You get to break out all of your shiny seed packets and indulge in grandiose visions of all the food you will grow this year!

I have used just about every seed starting medium there is. You name it, I've tried it in one form or another. So, here is my take on what is available to us permies.

1. Expanding soil discs:

This is what I used when I first started. While they may be cheap, you get what you pay for with these. I had a mold problem when I used them, despite adequate ventilation. They also tend to dry out faster, and let's face it, the plastic isn't very permie friendly. The kits they sell in the big DIY stores are fine if it's your first time and you aren't sure if you want to start growing, but they are not a sustainable investment.

2. Seed starting mix:


Now this will give you the biggest bang for your buck. Plants grow well, no mold issues, and the plants do really well in the garden thanks to a well-developed root system. You have several options of mixes to choose from and most are organic.  But again, there is that pesky plastic issue, but you can re-use the containers for several years. Another drawback is that the process of filling each pack is very time-consuming. But hey, if you are on a tight budget, and you are a newbie, then this method offers the best choice for you to start some seeds.

3. Soil Blocking:


I am testing this out for the first time this year. So far, I enjoyed the ease of making these soil blocks, and it was much less time consuming than using the mixes. I do have to say that these buggers tend to dry out pretty quickly, oh, and I am absolutely awful at remembering to water them, so I would suggest that you use this method if you have experience in seed starting. I think I prefer this method, but the proof will be when I harvest all the goodies I intend to grow.

I have a blog post if you would like to read more about soil blocking:webpage

Check out my video on how to make soil blocks:webpage

Whatever you decide to use, just get growing!

I have been researching a little bit about DIY recipes for seed starting mix and my impression is that almost everybody adds either perlite, vermiculite or coco fibre for structure, aeration and water retention. I presume this is because regular garden soil will go dense and anaerobic over a couple of weeks. Is that correct first of all?
Or if not are there ways of amending my garden soil with things that are commonly found in Gardens as in things I don't need to go and buy, such as maybe saw dust? If I makes my screened composts with 50% sawdust, Will that work? Or is the sawdust maybe a platform for excessive fungal growth that is bad for the seeds?

And last question, is there any truth to the myth  sterile seed mix? Four example are there specific types of seeds that require this, clearly it doesn't apply to a lots of seeds as I have never used sterile mix before. However there have been types of seeds that I have always had trouble with. Two examples I can think of our parsnips and parsley.

Thanks a lot!!

for structure, aeration and water retention. I presume this is because regular garden soil will go dense and anaerobic over a couple of weeks. Is that correct first of all?  

It is possible but not necessarily so.  Consider how your garden soil responds to water.  Does top water tend to run off or puddle or run through to fast. If you plan to bottom water your seed starting medium put your garden soil in your starting container when dry and see if it will wick water to the surface.  Depending how you have been improving your soil It may have reached seed starting medium which is what you want for direct seeding in the garden.

Or if not are there ways of amending my garden soil with things that are commonly found in Gardens as in things I don't need to go and buy, such as maybe saw dust? If I makes my screened composts with 50% sawdust, Will that work? Or is the sawdust maybe a platform for excessive fungal growth that is bad for the seeds?  

Sawdust varies so much in particle size and wood character, it is hard to give a direct answer.  It could be hydrophobic or if fine tend to compact when wetted.  Fungal growth that breaks down the sawdust may be good but slow germinating seeds could be consumed by organisms in the compost.

And last question, is there any truth to the myth  sterile seed mix? Four example are there specific types of seeds that require this, clearly it doesn't apply to a lots of seeds as I have never used sterile mix before. However there have been types of seeds that I have always had trouble with. Two examples I can think of our parsnips and parsley.  

Your sawdust is relatively sterile, mixed with sandy soil it may make a good starting medium for slow germinating seeds in a small volume which then cam be transplanted into a rich starting medium to feed the starts.
The permaculture principle is observe, make triles and observe, ese what works in your environment.

Uncomposted sawdust robs nutrients and is acidic. A very important ingredient in seed mixes is sharp sand.

Thanks a lot for that explanation hans,– that Clarified a lot of things for me. I understand that sharp sand is something quite different from beach sand, Which is the one I have available here for free. Will beach sand clog and go dense? Or Wil lit do the job just not as well as sharp sand.

brian haitz wrote:Thanks a lot for that explanation hans,– that Clarified a lot of things for me. I understand that sharp sand is something quite different from beach sand, Which is the one I have available here for free. Will beach sand clog and go dense? Or Will it do the job just not as well as sharp sand.

"It depends..."  Beaches can be very different.  Sharp sand has all the fine stuff washed out.  Waves and current can do that or they can leave a pile of mud.  Do the jar test, where you put your soil or  beach sand in a jar with water and shake it up and watch the layer settle out. sharp sand will settle first.