Recipe for Organic Potting Soil Mix

Organic potting medium

For home composters who frequently use potting mix, making their own soil for container gardening—without using expensive store-bought ingredients—is a big money saver that's well worth the time and effort.

Compost should be screened before it's added to homemade potting mix.
Compost should be screened before it's added to homemade potting mix. | Source
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Why not store-bought mix?

It's probably not completely organic.

Potting medium from the local garden center or discount house usually contains a variety of organic material, such as vermiculite (hydrated laminar magnesium-aluminum-ironsilicate) perlite (volcanic rock), coir (coconut fiber), worm castings, bat guano, sand, peat (Sphagnum peat moss), compost, bark and/or soil.

And, unless it's 100 percent certified organic, store-bought potting soil will probably contain many manmade elements, too, including pesticides, herbicides and sythetic fertilizers.

FoxFarm FX14053 12-Quart Ocean Forest Organic Potting Soil
FoxFarm FX14053 12-Quart Ocean Forest Organic Potting Soil

Organic potting soil can be expensive. Those who compost can make their own for much less.

 

How much do you spend on potting soil a year?

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Even potting soil ingredients such as lime, which seem organic at first glance, may actually contain synthetic bonding agents as well as other nonorganic additives as a result of the manufacturing process.

Store-bought mix is expensive.

If you do lots of container gardening, buying potting soil at the local garden center or discount chain can be an expensive proposition, especially if you buy better quality mixes.

Although we do most of our gardening in beds and islands, it would take about 20 large bags of commercial potting soil to fill the containers in our flowerbeds, entryways and deck. If we buy the really good stuff, that's over $200 on soil alone!

For  home composters, making potting soil can be as simple as combining soil with screened compost & pasteurizing it.
For home composters, making potting soil can be as simple as combining soil with screened compost & pasteurizing it. | Source

Easy Organic Recipe

For home composters, the easiest, least expensive recipe for homemade organic potting soil has got to be a simple 50-50 mix of homemade compost and garden soil.

What's Organic?

Organic ingredients are comprised of matter derived from plants and/or animals. Organic ingredients are all natural, and do not contain any synthetic or manmade elements.

The beauty of this recipe is that it uses what you have on hand, so there's no need to buy anything to add to the mix.

The only drawbacks are that making it isn't as easy as simply mixing the two ingredients together.

The compost must be screened, and both ingredients must be heated in order to kill harmful pathogens, fungal spores and weed seeds.

Chicken wire wrapped over a wooden frame works well for screening out large chunks of compost.

As for the pastuerization process, you can go about that any number of ways.

How to Pastuerize Potting Mix

Small Batches

If you're pasteurizing small batches of homemade potting mix, you can do it in the oven.

Simply moisten a few quarts of mix and bake it in an aluminun foil-covered cooking pan at about 180 degrees F for 30 minutes.

Stick a meat thermometer into the foil and check on the soil every so often. When the thermometer registers 150 degrees F, turn off the oven, leaving the pan inside for another 30 minutes.

Potting Soil on the Cheap

The cheapest, easiest way to make your own potting soil is to use the organic material that you have on hand rather than buying organic components often used in packaged potting mix, such as bonemeal, perlite and vermiculite.

Check the thermometer periodically to make sure that the temperature doesn't shoot up to 190 degrees F or more. If it does, leave the oven door open for a few minutes to bring the temperature down.

Large Batches

For large batches of potting soil, place the mix in a heavy-duty black garbage bag and set it in a sunny spot in the garden for several weeks in summer. As temperatures rise, the mix will cook.

Frequent Batches

If you intend to cook up lots of organic potting soil over a period of time, consider building a solar cooker , such as the Kyoto Box solar cooker, out of cardboard boxes.

Easy Potting Soil Recipe Variations

If you have them on hand, composted barnyard manures, leaf mold, and/or a sprinkling of wood ash could be added to the mix prior to pasteurization.

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Comments 21 comments

The Dirt Farmer profile image

The Dirt Farmer 3 years ago from United States Author

Thanks for linking your hub, Suzie HQ! Your air-purifying houseplant hub is a perfect article to read along with this one. I added the link at the bottom and in the first paragraph of the Knox gelatin fertilizer hub, too. Have a great weekend! --Jill


Suzie HQ profile image

Suzie HQ 3 years ago from Dublin, Ireland

Hi Jill,

What a great article and as a container gardener, I have spent so much on potting soil in the past. Thanks for great information and ideas. Love to link this to my best houseplants for air purifying if okay? Cheers, Jill for another awesome article! Voted up, useful, interesting, shared and pinned!


The Dirt Farmer profile image

The Dirt Farmer 3 years ago from United States Author

Hi Patricia! Hope you're doing well. Your mama knew what she was doing! We have oodles of compost-in-progress right now. Ah!!! Think I'm going to bury a bunch of it rather than bake! Nice to hear from you. All the best, Jill


pstraubie48 profile image

pstraubie48 3 years ago from sunny Florida

This is so interesting, Jill. My Momma used to bake soil sometimes to kill nematodes that would eat the roots of her plants. I do not recall her baking the soil to use it as you have suggested. I do have some compost going so I may just have to give this a try. Thanks for the clear directions.

Angels are on the way ps


The Dirt Farmer profile image

The Dirt Farmer 3 years ago from United States Author

Oh, leaf mold! How wonderful, Pearl. That's the stuff! Thanks for dropping by & commenting.


grandmapearl profile image

grandmapearl 3 years ago from Southern Tier New York State

Jill, this is excellent info! I will be bookmarking this for future reference. We have a composter for all of our kitchen veggie and fruit scraps. The bottom has a place where the finished compost can be shovelled out, which is very convenient.

We have lots of leaf mold and wood ash that I like to add from time to time as well. I'm glad to know that I'm on the right track! Voted Up+

Pearl


The Dirt Farmer profile image

The Dirt Farmer 3 years ago from United States Author

Hi Torrilynn! Isn't your grandma lucky to have you! If you already have compost, making your own potting soil really will save you guys money.

Maren--Hope you do try it. I'm going to try to see how little I can spend on gardening this spring and summer and still have a nice one. Thanks for commenting!--Jill


Maren Morgan M-T profile image

Maren Morgan M-T 3 years ago from Pennsylvania

I am going to give this baked compost a try!


torrilynn profile image

torrilynn 3 years ago

TheDirtFarmer,

thanks for this recipe for organic potting soil

my grandma loves for me to help her with her

gardening and flowers so im sure this will really help with saving money

on potting soil. thanks and voted up.


The Dirt Farmer profile image

The Dirt Farmer 3 years ago from United States Author

Ah, the smell of baking dirt! Thanks for the comments, aviannovice.

Oh, Donna! I hope you get a little patch of dirt to call your own. I know what it's like to live in tiny apartments and miss gardening. Take care! Jill


donnah75 profile image

donnah75 3 years ago from Upstate New York

So wishing I had more space than my apartment patio! Oh well, I am pinning this good advice for when I do :) I am also going to share it with my sister in hopes that going forward I could "source" these materials from her property. Good garden advice, as always. Thanks.


aviannovice profile image

aviannovice 3 years ago from Stillwater, OK

When IU was a kid, my father used to bake dirt in the oven and used that for planting the seeds in the house. Now is sure the time to be doing this, with spring right around the corner. Great work, Jill.


The Dirt Farmer profile image

The Dirt Farmer 3 years ago from United States Author

Hi Randy. The pasteurizing is of the mix of compost and garden soil, not just compost alone. I wouldn't put homemade potting mix that contains soil straight out of the garden in containers in my home without pasteurizing it because of possible active pathogens and insect eggs, but ... everybody's different. (:

Hi Radcliff! It's hard to know exactly what's in stuff, huh? Nice to hear from you! Jill


Randy M. profile image

Randy M. 3 years ago from Liberia, Costa Rica

I've never pasteurized my compost, the composting temperatures are more than adequate for making a healthy compost. And I usually presort, add some soil and mix with a shovel a couple of times during its natural cooking before use on the garden.


Radcliff profile image

Radcliff 3 years ago from Hudson, FL

Wow! I had no idea that organic potting soil isn't really organic. Thanks for the great info, as usual!


The Dirt Farmer profile image

The Dirt Farmer 3 years ago from United States Author

Hi Ms. Dora! Thanks for reading & commenting. I'm off to help my husband build a fence. (Our dog bit the mailman!) Hope you have a great day! --Jill

We never really have bug problems here either, LongTimeMother, and I credit not using pesticides & herbicides for that, although Japanese beetles can be irritating at times. (They must taste awful!) Happy gardening! Jill


MsDora profile image

MsDora 3 years ago from The Caribbean

Very interesting! Very useful! Thanks for the lesson and I'm off to do my practicals. Voted Up.


LongTimeMother profile image

LongTimeMother 3 years ago from Australia

I rarely chop things, but I do tend to 'sort' instead of just throwing everything into my compost. For instance, when I pull my corn plants out at the end of the season, I just drop them in a pile on top of part of the garden that is 'resting' and leave them to break down there. These days I feed them to the pigs, but I haven't always had pigs. I have a friend who tries to include her massive corn stalks directly into her compost after she chops them a little, and wonders why she can't get effective results.

I take care of bugs with home-made sprays outdoors, and just squash the occasional aphid that I might discover indoors. My potted plants get the occasional comfrey leaf fed to them, as mulch or in a tea, and I keep a thin layer of mulch on them at all times.

I've always found when the plants are healthy and I'm keeping an eye on them, there's not been a bug problem. Even when the garden next door is being savaged, my plants miraculously escape trouble. Might have something to do with companion planting etc, but I am a pretty low-key gardener so I give credit to the soil and the plants for the good results. :)


The Dirt Farmer profile image

The Dirt Farmer 3 years ago from United States Author

Hi Jackie. It kills me to spend money on dirt, too! You're welcome. Glad you commented.

Hey LongTimeMother--Sounds like you make great compost! Mine always has chunky stuff in it, probably because I'm too lazy to chop up everything before I dump it into the pile. If it gets hot enough and smells good, it should be pathogen free, but ... your garden soil isn't. I'm surprised you haven't had issues with bugs, etc., especially with the potted plants you grow indoors year round. But hey, if it's not broke.... Glad to hear from you!--Jill


LongTimeMother profile image

LongTimeMother 3 years ago from Australia

lol. I find this hub very interesting, but I confess I've never screened or cooked my potting mix. I find if I keep my compost hot enough and toss it regularly, it smells good by the end of the process and then I just use it in pots, mixed with garden soil. I don't like the idea of putting compost in my oven, but I know lots of people do. Voted up.


Jackie Lynnley profile image

Jackie Lynnley 3 years ago from The Beautiful South

This is some great info. I spend a fortune on potting soil and even waiting for sales it can get expensive. Thank you.

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