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homemade potting mix vermiculite?

Provo, UT(Zone 5a)

reading the home page on homemade potting mix..i couldnt agree more!!
question to all out there... i dont use reason really..i do use perlite..
reading the home page..that vermiculite adds some good minerals to soil mix..
so?? what are experiences of you all on your homemade potting mix ..and especially your
feelings if you use vermiculite..
my personal mix..
my own compost,coco coir,perlite,worm castings
my plants do great in it.. but ive got to go to home thinking ill buy a
big bag of vermiculite and add to my mix..
thanks all...

Bay City, MI(Zone 6a)

My honest opinion is that container soils are all about structure and particle size and very little about their nutritive value. When you have any combination of very fine ingredients, like compost/coir/worm castings, it's impossible to amend them with perlite and expect improvement in either drainage (flow through rates), aeration or the ht of the perched water table ..... and your mix is going to support a rather tall perched water column, which is always going to be a limiting factor.

Vermiculite is very unstable - structurally. It breaks down quickly in soils, compacts, and increases water retention, something a soil comprised of fine particulates can ill-afford, so I wouldn't consider adding it to your components. If anything, I would add a LOT of perlite to reduce water retention. It won't do much for your flow through rates, aeration, or the ht of the PWT, but it WILL reduce the o/a volume of water the soil is capable of holding. The only saving grace in that is, with the soil holding less water, it will dry down a little faster, allowing very important air to return to the soil so roots can breathe again.

It's much better to start with large particulates that ensure the best aeration and a near absent PWT and amend the bark with a small volume of the fine ingredients (less than 1/6 of the mix), than it is to START with fine ingredients and try to get them to drain, the latter being an exercise in near futility because the soil won't take on any of the drainage/aeration properties of the larger particles until they are around 75% or more of the whole.

I can show this more clearly with an illustration if there is any interest.


Provo, UT(Zone 5a)

thanks tapla.. ive seen vermiculite break down fast.. i think i'll stay with my mix..minus the vermiculite..
i am always desiring to learn more... some things work in different areas..and soil conditions..
here in utah.. i have to mulch things alot (tomatoes) so the soil doesnt dry out so fast in july and august
i hope you will put up illustrations..
thanks much..

Bay City, MI(Zone 6a)



Provo, UT(Zone 5a)

hi tapla..
you mention in your previous post..."i can show this more clearly with an illustration if theres an interest"
i thought maybe u had some graphs or something..

Bay City, MI(Zone 6a)

Oh - I meant a verbal illustration. Here is a copy paste from another hread that might be helpful in understanding particle size relationships:

Use your mind's eye to picture what happens when you mix sand into a jar filled with marbles. You can fill a jar with a quart of marbles, but still pour a pint of sand into the jar - so did you ACTUALLY fit 1-1/2 quarts of material in a 1-quart jar? If you envision this arrangement, sand and marbles, what do you think the drainage characteristics would be? There's a quart of marbles but only a pint of sand, yet the drainage characteristics AND height of the PWT will be exactly that of pure sand. The only thing that changed by mixing them together is the o/a volume of water the mixture CAN hold.

The same can happen with the bark/peat/perlite mix. If you start having to add significant fractions of fine material (over about 1/6 of the whole) to increase water retention, you end up reducing drainage AND increasing perched water. This is precisely why adding a little bark and perlite to peat or bagged soils won't work as well as starting with a favorable size bark when building soils, and why adding a lot of peat to large bark doesn't work well either.

I think this is probably the clearest example (I've offered) as to why particle size is so important to how container soils function.

Provo, UT(Zone 5a)

much thanks tapla..
i often think of my soil as a cross section.. i think it helps me what the plants will need to be happy campers
i live in a river bottom area. u dont have to dig very far..and its
often i think..enough of all these rocks.. but.. truely.. it provides great drainage..
joke in my neighborhood on me is if we ever have a flood.. to come to my ive added so much soil,compost
its the high ground.. LOL
again..thanks for your illustration tapla....

Helena, MT

Dave, tapla is right on the money here about perched water. I have down loaded over 20 pages of information Al has posted recently in several threads attempting to come up with a suitable growing media for my raised beds which up until now have only been good for leaf lettuce.

You and I both Dave have had great success in the past using well aged vermiculture media, worm castings, or as I prefer to call it spent media for the purpose of starting seeds. Due to an increase in the number of transplants necessary for the raised bed plantings I thought it would be a good idea to add some peat moss fines to the spend media (also peat moss) to double my volume of germination mix. It was a complete bust for my first tomato and pepper plantings. Nothing came up! After going back and rereading Al's postings the reason seemed clear to me. I went back to straight spent media and all seeds sprouted fine as before. So as an experiment I tried mixing the spent media with perlite for my backup plantings yesterday. As Al says there are some draw backs here for the potting mixes you are talking about but I think the method I use for germinating tomato and pepper seeds initially in peat pots and then potting them up individually in the same will be enhanced some with the addition of perlite. I incorporate bottom watering as well as fine sprays in this process which can get a bit tricky with peat pots, but I have used them for s number of years with good success. I know very few people who actually like peat pots but I will stick with them. To me peat pots are like my vermiculture just need to know how to read them and when to add water or back off.

Go for the illustrations Dave. Al's reads are truly fun as well as informative. Some great analogies there.

Provo, UT(Zone 5a)

i will have to take in them morgan..
i think with my garden soil.. the drainage is so high ..all the rocks.. from shaking my head..LOL
i put in a new raised bed.. i think i will add a bag of vermiculite to it..
its mostly coir,peat,compost, leaf commpost..
the tropicals will be going into it..
with all the is important to keep some good gardening practices in place..for health
and success for plants..
we had snow yesterday.. i think its to rain tonite/morning..
the grass is so green.. sure pays to put down winterizing fertilizer in fall.. :) yea.. !!!
hope youre getting a bit of a warming up there in helena ...

Helena, MT

Not much Dave. Weather is way too cold to even think about planting outside. Even the covered raised beds will be about a month away. I have been reviewing as much information as I can from postings in the container gardening and raised bed gardening postings in attempt to get several raised beds ready. I plan to keep it fairly simple this year with mostly lettuce and cole crops in the raised beds. The main garden serves for everything else. The majority of the produce from the main garden goes into some form of storage such as canning, freezing, dried storage and preservatives. The raised beds are exclusively from garden to kitchen and hopefully with all this great information of late I can get up to eight months of production from the raided beds.

Everett, WA(Zone 8a)

I read in one place that "pepper seeds don't like peat". (Sorry, I can't find that link or recall what he sugegsted using instead.)

I've read everyone else say that they start their pepper seeds in a mix of mostly-peat.



Helena, MT

Corey, I typically use my spent worm media which is originally peat moss which has been soaked and drained to remove excess acid, and this spent media works great as a germination mix for pepper seeds. However, adding fifty percent soaked and drained peat moss fines to this mix to streach it out did not work at all. I have been potting up pepper my hot plants to 2.5 gallon plastic pots for a couple of years now and I can say the results is that good. Although I use peat moss in the potting mix I am beginning to wonder if its a problem with drainage and aeration as we have been discussing in several forums. Smokin Joe and Ozark are pretty good with hot pepper plants so probably they could help with this in the pepper forum.

Provo, UT(Zone 5a)

not growing any peppers ..but my tomatoes sure are doing great with my mix..
coco coir,commercial mix..mostly peat,perlite,and castings..
ive been busy..and havent gotten them transplanted to 4" pots yet.. LOL i gotta get that
done.. im really glad i started my own tomato plants from seed.. ive been so unhappy
with plants ive bought from local nursery last few yrs..
now if we can just get some warmer weather..
it snowed today.. its melting..but geeshhh.. enough.. LOL

Everett, WA(Zone 8a)

Tentatively, if 99% of the people growing peppers are happy with starting seeds in peat, it can't be TOO bad. I've been unable to find that one source4 that siad "never start peppers in peat".

it wouldn't surprise me if your killing the acidity addressesed whatever imaginary hazard peat poses for peppers. OR, the guy who hates it may be doing something that reduces drainage, and then peat is a killer FOR HIM.

>> However, adding fifty percent soaked and drained peat moss fines to this mix to streach it out did not work at all. I have been potting up pepper my hot plants to 2.5 gallon plastic pots for a couple of years now

>> I am beginning to wonder if its a problem with drainage and aeration as we have been discussing in several forums.

Just recently I've been delighted by the improvement in drainage and aeration caused by adding lots of pine bark (shredded, chipped, ground, screened, from mulch or orchid bark, whatever). You can't beat the price (2 cubic feet for $4-8) or chunkyness.

But I think you have much more experience than I do.


Helena, MT

I agree that drainage and aeration are just as important in germinating as in pots, raised beds as well as your garden. The tomato seeds I planted in the 50:50 spent worm media and perlite are looking fine. I'm still waiting on several hot peppers. I am planning on mixing some potting up material today for tomato and pepper seedlings. I will be adding some wood chip fines to the mix for the first time. I understand that wood chips have the effect of taking up nitrogen so I figured I would offset that with extra composted manure. Hope it works! I still think I will stick with some of the best seedlings in the 100% spent worm media. How does the saying go, "Don't fix it if it ainít broke!"

This message was edited Apr 10, 2011 9:56 PM

Everett, WA(Zone 8a)

>> "Don't fix it if it ainít broke!"

Aww, what's the fun in that? (I guess, "success is fun".)

Everyone tells me that Perlite is a great way to improve drainage, despite being round as a marble.

I don't know why I don't like it, it just looks wierd to me. And the way it "floats" makes me think of styrofoam. I'm hoping that coarse crushed granite will work as well or better, so that I don't need to think up a rational reason for not using more Perlite.

Bay City, MI(Zone 6a)

Perlite actually does very little for drainage/flow-through rates after a couple of waterings. It's primary benefit is that it reduces o/a water retention by taking up space that would otherwise be occupied by water. Unless the perlite is a SIGNIFICANT fraction of the soil (like over 60%), it just doesn't change drainage OR the ht of the PWT.


This message was edited Apr 11, 2011 5:00 PM

Helena, MT

My error, what I meant to say 50 percent spent worm media and 50 percent perlite for my germination mix. I am still working on a means to provide water flow in the mix which I plan to use in my raised beds. Yesterday I picked up a 24 pound bag of perlite and asked about the vermiculite. The nursery owner simply said with all the problems at Libby where it is mined her in Montana he quite carrying the product. I asked him what the problems were and he said carcinogens. I said, "Asbestos?", and he replied yes. So cross that one off my list. I did however pick up 200 pounds of oyster shells at Murdocks, thinking I had read somewhere in this thread or like thread that this would be a good source of inorganics. I realize I am diverting from potting mixtures, however I think some of these principals still apply to raised beds as well.

And Corey , I agree it is fun to experiment at least on a small scale. I do have my concerns about messing up 32 cubic feet of growing media though.

Al, I have one question for you on a related matter here. Since wicking to remove perched water is a good idea in pots, what about a layer of wood chips in the bottom of a two foot deep raised bed? Again I apologize for bringing this up here but there seems to be a corollary in my mind. Since wood chips do not effectively remove perched water in the bottom of a container; and setting one pot inside another; or setting pots in a trench can remove perched water; would a six inch layer of wood chips sitting on soil (even my rock clay soil) act as a wick?

Everett, WA(Zone 8a)

>> Unless the perlite is a SIGNIFICANT fraction of the soil (like oer 60%), it just doesn't change drainage OR the ht of the PWT.

Perhaps it is the total fraction of "large pieces" that determines drainage. For example "30% perlite plus 30% gravel" or "30% perlite plus %30 pine bark chunks".

Or perhaps to be effective, the mixture of materials forming the "coarse fraction" might need to be somewhat similarly-sized to prevent 'nesting' or 'intercalating', or whatever one would call "smaller things pluging the gaps between bigger things".


Provo, UT(Zone 5a)

to continue this discussion..
how about pumice??i think my trouble with perlite has been
as al said.. % needs to be high to get benifit of better drainage..
i plan to buy alot more perlite this spring for potting up use..
but also..pumice.. its somewhat heavier..but wont break down
like perlite..also ive bought so far..are various shapes..not
still early to plant anything..sigh.. but im getting my "stuff" together..

Helena, MT

I was watching a video where crushed rock fines were being added to the soil along with compost for micronutrients. Fortunately we have numerous rock quarries here in Helena which gives a way crush rock fines. Just take you buckets and fill....they even provide the shovels at my favorite one. I have been using these fines as tapala suggests in potted plants for drainage. However it has been ten years since I started gardening here in Helena and I figured it was about time to rejuvenate the garden as well. I have also decided to use crushed rock fines in my raised beds this year as well as in my windrow vermicompost piles. So if your lucky possibly you can find a rock quarry near you.

Provo, UT(Zone 5a)

hey morgan..the man !!!
ya..i have a fellow garden friend that gets rock dust at a local
rock process plant..its really close..
im thinking the same thing... get a dozen or so 5 gal buckets full
of rock powder.. and distribute it all over the gardens..
my friend gets it for free..just bring your own buckets and shovel..
good idea to add to your vermi piles too ...
i understand some commercial composters are adding to their
processes of spraying mycorrhiza on the piles..
i guess adding root friendly fungi as an "eco friendly" fungicide..
were getting snow tonite..:( sigh..

Helena, MT

Dave, after reading your comment " i understand some commercial composters are adding to their processes of spraying mycorrhiza on the piles.", I did some reading on mycorrhiza and it sounds like a fascinating subject.

I plan on doing some more research on the subject today. Since the AM type which is used for garden crops need to attach themselves to the root systems of the host plant I was concerned about the viability of the fungus in a compost pile. I had anticipated the vermicompost rows would need to be started in the early spring and would take possibly a year before the vermicompost could be harvested unless I can find a simple way to turn and water the piles on a regular basis. Static piles here just wonít break down quickly enough to be used in the same growing season.

I challenged Mantis to develop a windrow auger for the gardener but never heard back from them. But Iíd wager someone will jump on this idea and make a killing. A device like this could turn outdoor vermicomposting in to a gold mine and basically put the chemical fertilizer business into a tailspin.

Everett, WA(Zone 8a)

>> Since the AM type which is used for garden crops need to attach themselves to the root systems of the host plant I was concerned about the viability of the fungus in a compost pile.

I think that endomycorrhiza can exist both ways - as independent hyphae, and in symbiosis with root hairs. But one article urged multiplying them by growing certain crops with extensive fine root systems, then "harvesting" the roots.

Maybe they were daydreaming, but when I see seeds sprouting in my compost heap, I always think "oh, good, the mycorrhiza population is probably booming.

>> " i understand some commercial composters are adding to their processes of spraying mycorrhiza on the piles.",

That puzzled me. I thought the endomycorrhiza mainly helped take up water and minerals. Do they also help to break down organic matter? Maybe every microbe does, to some degree or other. And I suppose that any kind of fungus competes with every other fungus, so the "good fungi" may help keep down the "bad fungi".

But for pure speed of breaking down compost, I would think that many kinds of bacteria and fungi would be better adapted than this particular group, that's specialized for symbiosis with plant roots. Just my guess.

One good thing: you know that if has evolved to live in symbioses with root hairs, it certainly evolved to encourage plants and not harm them. Maybe they also evolved to combat soil diseases of plants, like "the enemy of my friend is my enemy".

Provo, UT(Zone 5a)

great to see some thinking on this..i think after i read some articles
i get what im looking for..but miss what others much thanks!!
as i understand.. the endo and trichoderma bacterias have a broad
symbiosis with plant roots.. the ecto are mostly affective on certain tree
for my use i look for endo,and trichoderma ..since with some of my tropicals
if there to much "activity" in the attacks the corms..and starts to break
them down.. sigh.. i lost an expensive amorph corm .. expensive experiment..
and lesson learned..
also..gleaning from Al ..i need alot more perlite/pumice in my soil mix
with some of my potted tropicals..for the drainage they need..
i agree morgan.. it wont be long when someone comes along and blows
the socks off some of these commercial potting mix companies..or their products..
dude... that should be u !!!! u are one of the most inovative.. practical guys i know
u could make a killing at something u love.. then sell.. and just fish all yr long..
:) hehehee

Everett, WA(Zone 8a)

If only! But I think anyone who starts a company has a day of rest for the rest of their life!

But thank you!

I thought I was the most impractical guy in the world: popping bark like popcorn, and wanting to make glass wool into spiral pretzels and I-beams and box-beams.

Helena, MT

Well my friends, my head is spinning with all this info. In my simple way of thinking the pathogenic mycorrhiza are pretty much limited to species other than the AM which appear truly beneficial to our veggie gardens. Cultivating them is still something I can't get a good grip on. Spraying them on a vermicompost pile which may have to overwinter here before it s useful doesn't appear to be a viable cultivating process for me, as well as trying to cultivate from the roots of crops at the end of the season. Therefore, I feel I am left with only one option and that is to apply a spray, or solution made from powdered mycorrhiza each year to my crops much like adding inoculants to peas and beans. The solution method could possibly be a powder dissolved in vermicompost tea at the time of application to maximize the dosage over a much larger area....just some thoughts bobbing through my head.

Everett, WA(Zone 8a)

>> apply a spray, or solution made from powdered mycorrhiza each year to my crops much like adding inoculants to peas and beans.

Applying it to the seeds or in a furrow would certainly concentrate it right where it will do the most good.

My belief is that mycorrhiza have evolved to live in soil, form spores in soil, and spread from plant to plant. Your plan will guarantee that that your crops get plenty of what they need whether or not it is already in your soil or not.

After the first year, I would expect them to propagate themselves. The roots remaining in the soil, the independent fungal hyphae remaining, and spores formed by them,, should all assure that plenty of innoculum will overwinter for next year's crops.

Helena, MT

Corey, I believe out winters are too harsh to assure a next season supply of mycorrhiza, just as with the native worm situation. Each year I build up the soil with added compost seems to be helping. I did watch a two part U-tube about cultivating mycorrhiza which was somewhat helpful. The author used a worm weather grass seed in plug trays to start the cultivation process indoors. Then he plugged the individual grass sprouts in collapsible potato bags to be transplanted to the garden. It wasn't clear but I figured he would plug the grass close by his plants where he wanted to transfer the mycorrhiza. I figured a modified version of this approach could work here if you skipped the grass part and just applied the spores to your transplants. I will back into the source of the spores which I think are available close by in Idaho. Although transplanting beans and peas in not generally done I am considering the same approach with pole beans and peas next to my corn plants once they get about 4 to 6 inches tall. Both the inoculant and mycorrrhiza could be added to the beans and peas sown indoors, then transplanted next to the corn plants.

Everett, WA(Zone 8a)

>> Then he plugged the individual grass sprouts in collapsible potato bags to be transplanted to the garden.

The paper I read grew some crops , then chopped them down and withheld water to encourage the MR in the roots to sporulate. Then they dug out the root zones and chopped them into short lengths, keeping some soil as well. That was the inoculum.

- - - - - - - -
"In this soil a mixture of host plants are sown - members of the
grass and legume family have been shown to be infected by mycorrhizal fungi easily: maize and beans
are a good combination, or millet or other members of the grasses family with a legume such as lentil.
Onions or leeks are good too. These act as bait, allowing the mycorrhizal fungi that are present in the
soil to infect their roots and therefore multiply.

These plants are grown on for at least 3 months (depending on season).

At the end of this period the host plants are cut down and all watering stops. This effectively kills the
plant and tricks the mycorrhiza that has infected the roots into quickly releasing spores. After one further
week the roots of the host plants are pulled up, roughly chopped into 1cm long strips and mixed back
into the soil. This soil and root mixture becomes your inoculum."

- - - - - - - - - - -

This message was edited Jan 31, 2013 1:34 PM

This message was edited Jan 31, 2013 1:35 PM

Everett, WA(Zone 8a)

I admit I know nothing about cold tolerance of fungal hyphae. This is just speculation on my part. But spores are usually un-killable little things.

Whatever plants are wild in your region must have some kind of locally-adapted mycorrrhiza (I'm going to call them MR since I can't spell!) The advantage it confers on roots is to great for them NOT to evolve. Those ought to be able to over-winter, even if they come back from spoors and are slow to repopulate the soil in the spring.

If all your local wild plants are woody, their locally-adapted ecto-MR wouldn't help your crops at all.

And I have read that there are MANY varieties of endo-MR, and each family of plants probably has its own p;referred (or needed) variety of endo-MR. It sounds like you've researched that more than I have. If (say) beans need specific MR varieties that are NOT local and NOT cold-adapted, you might well be completely right and you might have to supplement the soil.

Maybe, since they do exist free in the soil as well as inside root hairs, you could collect a few shovelfuls of soil from each harvested row of crops, along with roots. Make a large compost heap in a sheltered spoot, perhaps underground or in a cold frame. If the c enter of the heap keeps itself warm enough to avoid hard freezing, you might have your own inoculum for next year.

And if you keep doing that for a few hundred or a few thousand years, you WILL evolve your own, locally adapted MR!

Helena, MT

I'm not sure that it's necessary to try and propagate a sustainable culture of Mycorrhize, and I'm not sure I could quantify the results to be sure my method of application. Inoculating half a row may be the only way to tell a difference.

Everett, WA(Zone 8a)

>> Inoculating half a row may be the only way to tell a difference.

That's "Science"!

Someone turned me on to a way to get a soil analysis for free. Add lime to 1/4 of the bed, high-N fertilizer to another 1/4. Add super-phosphate to another. Add green sand to the other.

Which one turns greenest?

Actually, you have to overlap them, since probably your soil needs more of everything.

Actually, the idea came from someone wondering if he needed more lime in his lawn. So he used his applicator to write the word " L I M E " on his lawn. Sure enough, that word came up greener, so he knew he needed more lime.

Helena, MT

That's funny Corey. Reminds me of the first time I used a fertilizer spreader on my lawn. I never did get the darn thing adjusted properly and boy did I have a funky looking lawn that season. I like to experiment with new ideas but I generally don't like to risk loosing a crop, so I keep the experiments to few test spots here and there. Raised beds are typically the places where I try new things each year.

I don't know if I am getting too far off the subject of Dave's posting here, but I just saw a U-Tube video of several guys building a layered garden in New Guiney. They used the term "no till" gardening which is the same as lasagna gardening, but it was the first time I heard anyone mentioning adding worms to the mix. I have always considering outdoor vermicomposting a form of gardening and frankly vermicomposting and lasagna gardening are basically one in the same. The only difference is in the lasagna garden or no till garden, a layer of straw is added to the top of with a series of transplants. It took those two guys just 30 minutes to construct the whole thing.

So now I'm off on another tangent. Instead of windrow vermiculture piles I think I will build some of these layered beds. Worms can still do their thing and I can grow some additional crops as well. At the end of the season this bed material can be recycled into next seasons garden as vermicompost.

Provo, UT(Zone 5a)

reading..and re-reading posts here.. thanks to u all
especially container forum..great thoughts there !!
im going to use more bark fines in my potting mix.. of the better professional potting mixes..farfard
their 1st ingredient in many of theirs is bark fines..
why try to recreate the wheel..:)
im pursuing sources of several cuyds of same sized fines now..
with my potted tropicals..i easily can use 2+ yrds of mix..
i cant find a "reasonable priced" source of "chunky" perlite..
the small sized perlite is ok for my small my biggest was have to have probably 50+% perlite for it to
function properly for drainage.. going to use pumice instead.. its similar sized to fines i want to im thinking will be good addition to my potting mix..
a bit more weight..but im tough..LOL :)
its early..for us in winter parts ..what are u all thinking on your potting mix
for this years growing season ???

Everett, WA(Zone 8a)

I saw that ProMix had a faster-draining variety - ProMix HP for "High Porosity"

Also, Sunshine makes "Mix #4" for faster drainage and more air.

Of course, both have peat so they will break down quickly.

Prices vary a lot. I would pay $38 for a big, 70 pound compressed bale.
Someone else paid $31 retail, or $26 with a discount.

Provo, UT(Zone 5a) does amaze me at prices out there.. pays to look around
before buying for sure..
the big 4 cu ft bales of good quality potting mix are up there..
locally i cant find going to make my own..
except im going to use as 1st ..highest content ingredient..
bark pines..
its snowing here .. sigh.. lol

Everett, WA(Zone 8a)

Someone sent me a mail, intending to say that she expected SNOW tomorrow.

Instead she typed something cosmic and intriguing -
"we expect NOW tomorrow".

Be here now!

Anne Arundel,, MD(Zone 7b)

when tomorrow comes , she can say Hey, now is here now.

Everett, WA(Zone 8a)

Apparently, both SNOW and NOW are there now.

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