Garden of Eatin' / How-To / Seeds & Seedlings

Make the Best Seed Starting Mix for Dirt Cheap (It’s Organic Too)

Make the best seed starting mix for dirt cheap (it's organic too)

When it comes to gardening, I’m all for getting started on a shoestring.

I order from seed catalogs, make newspaper pots for seed starting, recycle household containers for seedlings, reuse egg shells and egg cartons to start seeds, and scour the dollar store for cheap seed starting supplies.

But where I feel I get the most value, especially if I’m starting hundreds of seeds (which isn’t hard to do in a season when you think about it), is in making my own seed starting mix.

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DIY seed starting mix
Extra-Strength 32-Cell Seedling Tray with Insert

What is seed starting mix?

Go to a nursery and you’ll realize two things about seed starting mixes.

First, they’re relatively expensive. Sure, the price tag on a typical 8-quart bag doesn’t seem too bad, but then you bring it home and realize that 8 quarts isn’t really going to cut it when you have a whole flat of seeds to sow.

Second, some seed starting mixes contain chemical agents to hydrate the soil or supplements to supercharge your plants, which — for starting seeds — are completely unnecessary.

This is because all the nutrients that a seedling needs in its initial stage of life (before it develops its first true set of leaves) is contained in the seed. Think of it like an egg yolk for a baby chick.

A seed does not need fertilizer, compost, or beneficial microbes to germinate, nor does a seedling need any of that to grow healthy and strong in the first couple weeks. (You can read more about seed to seedling anatomy in this post — it’s truly amazing how self-contained seeds are.)

Seed starting mix is light and fluffy to promote root growth

Soilless seed starting mixes should only contain three ingredients — and you read that right, soil is not one of them.

I remember being confused when I first learned about soilless mixes. How does a plant grow without soil?

It all comes down to starting seeds versus growing plants. In the beginning, seedlings just don’t have the same needs their grown-up selves do.

The best seed starting mix (which you’ll learn to DIY below) is made of perlite, vermiculite, and sphagnum peat moss.

This blend is made specifically for seed starting, and it’s very light and fine-grained to help promote baby root growth and ensure the mix doesn’t get compacted in seed starting cells or seed starting containers (which are usually only 1 to 3 inches in size — tiny!).

Indoor seed starting
Heavy-Duty Propagation Tray

Is seed starting mix necessary?

You may be wondering why you need to use a soilless seed starting mix when you normally just plant your seeds in the garden, straight in the soil.

Here’s the thing: Garden soil has the advantage of being in the ground and living in harmony with the soil food web. It’s ideally well-draining and somewhat forgiving, as you tend to let Mother Nature take over and aren’t as obsessed over what does or doesn’t take off.

Unfortunately, garden soil tends to be too dense for seed starting and potting. It’s full of weed seeds. It’s teeming with microbes (both good and bad) and because they’re now constrained in an indoor environment without natural checks and balances, they can wreak havoc on your seedlings in the form of damping off or fungal diseases.

If you’re going to put forth the effort to start your seeds indoors, nurture them, and harden them off until it’s time to transplant, seed starting mix will give you greater success rates so you don’t waste seeds (or time).

Seeds started indoors

What’s the difference between potting soil and seed starting mix?

Generally speaking, potting soil is a growing medium that contains topsoil (in other words, plain old dirt) and some combination of bark, perlite, vermiculite, peat, humus, manure, and/or other fertilizers.

Potting mix is a similar growing medium that’s usually soilless, though commercially, you may find the terms are interchangeable and refer to the same thing. (You should always check the label of any bag you buy.)

Potting soil and potting mix aren’t ideal for seed starting because:

  • They have a coarser texture than seed starting mix, and you’ll often find chunks of bark in potting soil.
  • They don’t drain as well as seed starting mix.
  • They’re sometimes too rich in nutrients.

It’s not the end of the world to use potting soil or potting mix to start your seeds, but you’ll be paying a premium for ingredients that aren’t needed for germination.

On the other hand, if you don’t want to mess with repotting seedlings and just want to plant the seeds in their permanent container, you can start your seeds in a good potting mix that’ll continue to help them grow sturdy and strong.

Related: How to Repot Tomato Seedlings for Bigger and Better Plants

Get my recipe for homemade potting mix below.

The best seed starting mix needs only three ingredients

The best DIY seed starting mix needs only 3 ingredients

That’s the benefit of making your own seed starting mix at home — no synthetic fertilizers or synthetic wetting agents to worry about, just simple organic ingredients to get your seeds off to a great start.

Together, these ingredients provide the perfect level of fluffiness, drainage, and moisture retention for starting seeds.

  1. Sphagnum peat moss (not to be confused with the coarser and more fibrous sphagnum moss that’s typically used to line floral baskets) is an excellent, sterile, moisture-retaining medium. The finer the fiber, the more water-holding capacity it has.

    An alternative to peat moss is coco coir. This material is similar to peat in terms of look, feel, and moisture retention, but is made from the fiber of coconut shells.

  2. Perlite is an ultra lightweight volcanic glass resembling white popcorn ceiling, and it provides drainage and aeration.

  3. Vermiculite is a natural micaceous mineral, brownish and granular in appearance, with water-absorbing properties that facilitate re-wetting of the soilless mix.

All three ingredients are easy to find at most garden centers, but I’ve also linked my favorite sources online (below) if you can’t find them at your local nursery.

Organic seed starting mix made with perlite, vermiculite, and peat moss
Heavy-Duty Propagation Tray | Extra-Strength 32-Cell Seedling Tray

Basic Seed Starting Mix Recipe

A “part” refers to any generic unit of measurement to make the quantity you need, as long as it’s consistent: a scoop, a bucket, or a bag of each ingredient.

Combine all the ingredients in a clean tub or bucket, and saturate the mix with water. Stir the mixture with your hands or a trowel until it’s thoroughly moistened but not soggy (like a wrung-out sponge).

Add as much water as the mixture will absorb. You might be surprised to see how much it holds — peat moss can absorb 16 to 26 times its weight in water.

Homemade seed starting mix
Galvanized Round Tub

This initial watering makes it easier to keep the mix uniformly moist throughout the seed starting period, as peat moss can be difficult to re-wet if it’s been left to dry out.

Fill your seedling pots with the homemade seed starting mix, add seeds, and sprinkle a thin layer of vermiculite over your seeds if they need darkness to germinate. (Your seed packets should give any special instructions.)

You can save leftover seed starting mix for next season, or use it as the basis of your potting mix.

Homemade potting mix for seedlings and transplants

How to make the best potting mix for transplanting seedlings

With potting mix, we want to increase the ratio of peat moss (or coco coir) to up the moisture retention so our potted plants don’t dry out as quickly.

A basic potting mix is a good starter medium for transplants, but you’ll want to amend it with compost, garden limeworm castings, kelp meal, or other supplements depending on the nutritional needs of your plants.

Basic Potting Mix Recipe

Enriched Potting Mix Recipe

Enriching your potting mix with compost will help your seedlings and transplants thrive after the cotyledons die off. I like to start with well-aged compost, then add other amendments that inject a jolt of nutrients as well as increase microbial activity in the potting mix.

Make the best organic potting mix for less money

So just how cheap is homemade seed starting mix?

Let’s do a little math here and see how much we can save with this DIY.

A well-known brand of seed starting mix from a big-box garden center runs about $5 for an 8-quart bag.

While that doesn’t sound like much, note that 8 quarts is only 0.27 cubic foot.

Buying the individual ingredients from the same store means I can make a little over 1 cubic foot of DIY organic seed starting mix for around $8.

The same amount of pre-made seed starting mix from the national brand costs $20. That’s more than double the cost for a product that’s ridiculously fast and easy to make.

Some people might feel a little hesitant about the initial investment (2 cubic feet of vermiculite = $20, 2 cubic feet of perlite = $17, 3 cubic feet of peat moss = $12), but a little goes a long way.

If you keep these ingredients dry, they’ll never go bad and you’ll have plenty for your seed starting and potting needs.

Seed Starting Mix Sources

Make the Best Seed Starting Mix for Dirt Cheap (It's Organic Too) 1
Black Gold 8-Quart Canadian Sphagnum Peat Moss Plus | Premiere Horticulture 1-Cubic-Foot Sphagnum Peat Moss | Nature’s Premium 1-Pound Brick Coco Coir | GROW!T 1.5-Cubic-Feet Premium Loose Coco Coir | Black Gold 8-Quart Perlite | Espoma 1-Cubic-Foot Organic Perlite | Espoma 8-Quart Organic Vermiculite | Espoma 1-Cubic-Foot Organic Vermiculite | Dr. Earth 1 1/2-Cubic-Feet All-Purpose Compost

This post updated from an article that originally appeared on March 15, 2011.

Linda Ly About Author

I'm a plant lover, passionate road-tripper, and cookbook author whose expert advice and bestselling books have been featured in TIME, Outside, HGTV, and Food & Wine. The No-Waste Vegetable Cookbook is my latest book. Garden Betty is where I write about modern homesteading, farm-to-table cooking, and outdoor adventuring — all that encompass a life well-lived outdoors. After all, the secret to a good life is... Read more »

48 Comments

  • Avatar
    Pearl
    December 22, 2020 at 6:12 pm

    Hi Linda. Because peat is acidic, and because most commercial seed starting mixes are mostly peat, they add at ouch of lime to raise the pH more toward neutral. Do you know the ratio of peat to lime? Thank you.

    Reply
    • Avatar
      Linda from Garden Betty
      December 22, 2020 at 6:15 pm

      Hi. You don’t need to add lime to seed starting mix. Lime acts slowly (it needs 3-4 months to fully take effect) so it doesn’t have an affect on seedlings. Also, peat turns neutral as it ages and especially the more you water it.

      Reply
  • Avatar
    TheRealJMcD
    December 22, 2020 at 6:12 pm

    This is one of the best explanations of anything that I’ve ever read. Thank you!

    Reply
    • Avatar
      Linda from Garden Betty
      December 22, 2020 at 6:15 pm

      You’re so welcome!! I’m glad it was helpful!

      Reply
  • Avatar
    Lisa Joan Murphey
    December 22, 2020 at 6:12 pm

    Garden Betty, I’m getting confused. I hit the link for make your own potting soil, so I’m assuming this recipe is when you transplant the last time into your container? So, you just use to make your own high premium potting soil is the sphagmum, compost, perlite, vermiculite with the Dr Earth, fish meal, bone meal, 2 aspirins, and crushed eggshells, compost, garden lime, worm castings (everywhere is out of stock) and kelp meal; No store bought soil at all? I’m using 20 gallon planting sacks for the larger growing tomatoes. May I use regular potting soil then add the fertilizer and fish meal, bone meal, aspirins and eggs? That is a lot of ingredients! Ha! I’m a fairly disabled person and I don’t think I can gather and mix all those ingredients even though I’d love to. Could you give me a simpler way to get decent effects? I read good and bad reviews on the Fox Farm potting soil. Thank you. Lisa Murphey

    Reply
    • Avatar
      Lisa Joan Murphey
      December 22, 2020 at 6:15 pm

      Need an answer soon please.

      Reply
  • Avatar
    Bri
    December 15, 2020 at 9:31 am

    I was looking forward to this until I saw peat moss as an ingredient. Peat moss is soo destructive environmentally and as a gardener I am trying to be a custodian to the planet so I will not use this. I hope that you can provide a different starter mix that excludes peat with an explanation why we shouldn’t be using it. Thanks!

    Reply
  • Avatar
    Anon
    November 15, 2020 at 12:55 pm

    I think where most people go wrong is in having enough light so that their seedlings aren’t spindly and not repotting into an enriched soil soon enough. It’s fairly difficult to have enough light, at least where I live, but there are some fairly affordable LED grow lights that can help with that.

    Reply
  • Avatar
    Tina
    November 15, 2020 at 12:55 pm

    The very easiest way I have found to put drainage holes in containers or cups is this: heat a soldering iron. Put on gloves. Barely touch the bottom of your container or cup with the tip of the soldering iron and you’ll melt a hole. I put a fan near my work site to blow the fumes away. I bought a cheap soldering iron for this purpose 12 years ago and it is still working. Has anyone else tried this method? It is very fast and easy. For foam cups I use a ballpoint pen to push a hole in the bottom. Foam cups melt too easily with the soldering iron.

    Reply
    • Avatar
      Linda from Garden Betty
      December 22, 2020 at 6:12 pm

      That’s a great idea. I usually push or hammer a nail through my plastic cups to make my holes.

      Reply
      • Avatar
        Tina
        December 22, 2020 at 6:15 pm

        I started out doing that long ago but my cups would often split or crack. The soldering iron way is fool proof.

        Reply
  • Avatar
    sierra
    January 8, 2018 at 2:00 pm

    hey guys this didn’t work

    Reply
    • Avatar
      Linda from Garden Betty
      December 22, 2020 at 6:31 pm

      A few reasons you may have had trouble: not keeping the soil moist enough (usually the #1 reason), keeping the soil TOO wet (which leads to rot), sowing the seeds too deep, poor germination rate on the seeds (often due to quality or age), or not sowing enough seeds for the particular variety you’re trying to grow.

      Reply
  • Avatar
    2lumpsofclay
    February 24, 2017 at 11:47 am

    This is a seed starting mix-not a potting mix. Potting mix is what you use in “pots” for transplants or full size plants. The above is a soil less mix used to start seeds which will be transplanted. It contains no food since the seed has all the energy (food) in the seed itself that it will need until roots become available for feeding.

    Reply
    • Avatar
      Linda from Garden Betty
      February 24, 2017 at 4:58 pm

      If you read the whole post, you’ll see that the potting mix recipe is included as well, and I do differentiate between the two.

      Reply
  • Avatar
    The Plumbery269
    January 4, 2017 at 1:26 pm

    I hope you are aware the ink used to print newspapers etc. contain lead. Just thought you should know

    Reply
    • Avatar
      Linda from Garden Betty
      January 5, 2017 at 2:51 pm

      Decades ago, heavy metals in newspaper inks were common when newspapers were set in lead type, but these days, most newspapers (especially the major ones) use soy-based ink out of health concerns for their workers. This report by the USDA states that both b/w and color-inked newspapers can safely be used for mulch in vegetable gardens: https://semspub.epa.gov/work/05/79213.pdf

      If you’re worried that your local newspaper may still be using heavy metals in their inks, you should call them to verify.

      Reply
  • Avatar
    WatchingThe End Of Democracy
    November 5, 2015 at 5:54 am

    I use this seed start mix. it does a good job germinating the seeds, The problem that I have is when I go to transplant the seedling, the soil falls apart. I do soak before transplanting. Is there anything that can be added to the mix so it will stick together better?

    Reply
    • Linda Ly of Garden Betty
      Linda Ly of Garden Betty
      November 5, 2015 at 6:12 pm

      It’s a very loose mix, so it’s not meant to stick together unless you really pack it into your pot. You can try increasing the amount of peat used, but it’s not a problem for the mix to fall apart when you transplant (assuming you’re transplanting into soil anyway).

      Reply
      • Avatar
        WatchingThe End Of Democracy
        November 6, 2015 at 6:35 am

        Thank you for getting back to me so quickly. 🙂 I will add more peat. I was just concerned that the roots were being damaged when the soil fell apart as I tp. Again thank you for your hard work and knowledge that goes into this website. 🙂

        Reply
    • Avatar
      Ron Nichol
      February 13, 2016 at 4:08 pm

      I germinate only in vermiculite then start feeding with 1/2 strength fertilizer when the first true leaves start forming. Shortly after that I transplant into potting soil. The secret to transplanting from vermiculite is to get just the right degree of dampness: too wet or too dry is not good (but also not deadly to the seedlings if you’re careful. The day before I transplant I fully water the seedling plugs (which are in single cells). After drying for a day, the plug can be easily removed from their plastic cells and placed in a bigger pot with soil.

      My seedlings are placed in a clear, enclosed, plastic container that sits on top of a heat mat. If yours are not heated or are uncovered, they may be ready to be transplanted in less than 24 hrs.

      I expect that the same principles would apply to a germination mix of vermiculite, coir, peat moss and/or compost mixture.

      Reply
  • Avatar
    Rajiv S
    October 1, 2015 at 10:15 am

    Hello Linda, This is an Excellent Article I came across via google search regarding potting mix. Thanks!

    I have always used combination of Sand (80%) and Vermi Compost (20%) as potting mix and I do add Bone meal and Neem Cake relatively in small proportion. Additionally I use NPK fertilizer (foliar spray) along with Micro Nutrients. This has fetched me good results so far but the disadvantage I feel is, container gets very heavy because of sand (I am into terrace gardening) and I need to regularly water the plants.

    For past few days I was reading about Soilless Potting Mix/Enriched Potting Mix and now I am more inclined to use Coco Peat (which is very easily available in India), Perlite as well as Vermiculite because of their properties and hopefully it will reduce a lot of weight of the container, will provide good drainage and because of their water retention property, it may reduce the watering cycle. I will continue to use some part of sand as it provides stability to the plant.

    Regards

    Reply
    • Linda Ly of Garden Betty
      Linda Ly of Garden Betty
      October 7, 2015 at 1:32 pm

      Sand is very fast-draining, which is indeed a disadvantage if you’re using it for a potted plant that needs regular watering. I typically use a sand mixture for cacti, succulents, and other low-water plants.

      Good luck with making your own mix with coco peat, I believe you’ll have better results with that!

      Reply
      • Avatar
        Rajiv S
        October 11, 2015 at 3:22 am

        Thanks Linda! I am now using the composition of “Enriched Potting Mix” and beginning to see good results. Also the “seed starting mix” composition is showing very good results. I sowed Coriander (Cilantro), Fenugreek and Spinach a week back and they all have germinated well.

        Starting to use Enriched Potting Mix for Tomato, Brinjal (Eggplant) as well as Chilli (Hungarian Yellow Wax variety), they all are in a container, will transplant them.

        Reply
  • Avatar
    Tushar Sethi
    September 4, 2015 at 11:59 pm

    Hi Linda, I have used enriched potting mix for my seed starting is it ok?

    Reply
    • Linda Ly
      Linda Ly
      September 9, 2015 at 4:14 pm

      Yes it’s fine.

      Reply
  • Avatar
    BT RAO
    May 18, 2015 at 9:50 am

    Hello Linda,
    Just came here from google search, and happy to read your guide on potting mix.

    But i have one doubt, please kindly clarify.
    I bought Coco coir compressed brick of 5 KG weight, which can expand to 60/70 liters on adding water. How to measure coir in this case as in dried form or expanded wet form measn have to take water mixed coir to measure?
    I really appreciate your help in clarifying this.
    Thanks

    Reply
    • Linda Ly
      Linda Ly
      May 20, 2015 at 11:44 pm

      It does not have to be an exact amount. Just eyeball equal portions of dry coir, vermiculite and perlite, then thoroughly saturate the mix with water before using.

      Reply
      • Avatar
        BT RAO
        May 20, 2015 at 11:49 pm

        Thank you!

        Reply
  • Avatar
    Biplab
    November 13, 2014 at 5:19 am

    Hi Linda,

    I am from Kolkata, India. I have some hibiscus plant and some lemon plant in my Flat Balcony. They are used to get 6-7 hrs of Sunlight. But I am having problem like Leafs are becoming Yellow and also they are dropping from plant. What can be the cause and how to overcome from this problem. Any Idea. Thanks in Advance.

    Reply
    • Linda Ly
      Linda Ly
      November 14, 2014 at 10:27 pm

      Sorry, it’s hard to know since yellow leaves can mean so many things. Perhaps underwatering, overwatering, or a nitrogen deficiency.

      Reply
      • Avatar
        Biplab
        November 17, 2014 at 11:50 pm

        For Nitrogen which type of Food I can apply?

        Also one more thing I want to know that, for Rose tree how to prepare Potting Mix. It will very helpful for us if you let me know about this. Thanks in advance.

        Reply
        • Linda Ly
          Linda Ly
          November 18, 2014 at 3:45 pm

          If you don’t know the problem with your plants, an all-purpose fertilizer would be best. Choose one that’s fairly balanced in its N-P-K values. Or add compost, compost tea, or fish emulsion.

          And I’m sorry, but I’m not familiar with growing roses.

          Reply
  • Avatar
    Ravi Theja
    September 7, 2014 at 7:24 pm

    Hi,
    I’ve been using this potting mix but one problem i encouter always is that my seedlings tend to wilt off!
    What could be the reason?

    Reply
    • Linda Ly
      Linda Ly
      September 7, 2014 at 9:54 pm

      The wilting (damping off) is caused by different kinds of fungi. If your seed starting mix is sterile (never reused and always mixed with new ingredients), the fungi could come from pots or tools that haven’t been cleaned. Sometimes the fungi could be reintroduced via gloves, clothes, or other items that might come in contact with your seedlings.

      Reply
      • Avatar
        John Gabriel Arends
        January 1, 2015 at 12:25 pm

        What do you do with the potting/starter mixes from previous years if you don’t reuse it? Do you know of an affordable source to get these ingredients?

        Reply
        • Linda Ly
          Linda Ly
          January 2, 2015 at 5:44 pm

          I store unused potting mix in a covered container. You can use a lidded trash can or plastic storage bin (or something similar) for this. Mine just stays outside next to my potting shed.

          As for affordable sources, I get all of my ingredients from one of the local nurseries. They tend to have a larger (and better) selection than a big box nursery like Home Depot.

          Reply
  • Avatar
    josey
    February 2, 2014 at 3:53 pm

    Hi Linda, Could you grow grass out of yoiu soilless mixture ? EG: if i created the mixture could i then add grass seeds to it and it will grow ? Thank You ! & great blog 🙂

    Reply
    • Linda Ly
      Linda Ly
      September 18, 2014 at 11:28 pm

      Yes, you can sprout any seeds in the soilless mix, but eventually you’ll need to fertilize the plant or amend the soil if you want it to thrive.

      Reply
  • Avatar
    Kristin
    April 14, 2013 at 11:17 am

    Dear Linda: Can I start these seedlings outside rather than in the window of my apartment where I have such limited space? Thank you.

    Reply
    • Linda Ly
      Linda Ly
      April 14, 2013 at 2:02 pm

      Sure, as long as it’s warm enough outside to germinate the seeds.

      Reply
  • Avatar
    Andre David bowers
    August 27, 2012 at 4:21 pm

    HI Linda, I’ve been readign your bog entries, ideas on gardening , potting soil ideas, even the chicken tiki coop. I was about to post a pic of my hot Portugal Peppers and my cukes  but hmmmm I guess you don’t accept photos of other people’s  gardens, harvest etc. Thats Ok , I just wanted to say hi and   I enjoy  your ideas as  well as th erecipies  too!  Best of luck in the future with  your blog.

    Reply
    • Linda Ly
      Linda Ly
      August 29, 2012 at 12:44 pm

      Thanks!

      Reply
  • Avatar
    AshleyWaterstradt
    March 22, 2012 at 11:54 am

    Gah! I wish I had seen this before starting all my seeds! lol 

    Reply
  • Avatar
    Lorena
    March 15, 2011 at 8:21 pm

    How creative! it would be nice to have the extra space for things like this, but very difficult in nyc 🙁 … would love to have a whole garden with little herbs, flowers and gadgets.
    I love the concept of your blog! and you surf, how cool!..i wish i was brave enough but i think i’d break in half, lol..plus I basically just learned to swim..
    (p.s. thank so much for your comment! i changed my web name in case you want to follow the new one, traveldesignery.com is where i’ll be!)
    —Lorena

    Reply
    • Linda Ly
      Linda Ly
      March 17, 2011 at 9:19 am

      Haha I know, I used to live in NYC and the extent of my gardening was a couple of little pots on the fire escape!

      Thanks for stopping by and I’ll be sure to bookmark your new URL!

      Reply

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