Miracle Gro Seed Starting Potting Mix For Weed

Make the Best Seed Starting Mix for Dirt Cheap (It’s Organic Too) The best DIY seed starting mix needs only three ingredients, and you can find them all in your local garden center. Save money Can You Grow Cannabis with Miracle-Gro Soil or Nutrients? Miracle-Gro Slow Release Soil is Not Suited to Growing Marijuana! Many of us have grown up seeing Miracle-Gro being used in our homes, So I bought a bag of miracle gro seed starter mix. It's just peat moss, so I thought. I germinated 2 seed, paper towel method. when they sprouted a tap…

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

The best DIY seed starting mix needs only three ingredients, and you can find them all in your local garden center. Save money and get my no-fail recipes for organic seed starting mix and potting mix that you can easily make at home (all without complicated soil amendments and fertilizers). Keep them dry and you can store them to use next season too.

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

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.

Disclosure: All products on this page are independently selected. If you buy from one of my links, I may earn a commission.

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.)

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!).

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).

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.

Get my recipe for homemade potting mix below.

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.

    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.

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.

See also  Uk Weed Seeds

Basic Seed Starting Mix Recipe

  • 1 part sphagnum peat moss (or coco coir)
  • 1 part perlite
  • 1 part vermiculite

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.

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.

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 lime, worm castings, kelp meal, or other supplements depending on the nutritional needs of your plants.

Basic Potting Mix Recipe

  • 6 parts sphagnum peat moss (or coco coir)
  • 1 part perlite
  • 1 part vermiculite

Enriched Potting Mix Recipe

  • 4 parts sphagnum peat moss (or coco coir)
  • 2 parts compost
  • 1 part perlite
  • 1 part vermiculite

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.

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.

Common questions about seed starting mix and potting mix

Does seed starting mix or potting mix go bad?

Since seed starting mix and potting mix are soilless mixes, they don’t “go bad” or expire if they’ve been properly stored in a dry location. You can still use these mixes years after you make or buy them, but with one caveat.

One of the main ingredients in seed starting and potting mixes—peat moss—is an organic material that naturally decomposes over time. It doesn’t have a very long shelf life and after one or two years (from the time you purchase it), the fiber starts breaking down, making it ineffective at its primary job: to hold moisture.

Expiration in this case doesn’t mean the peat turned moldy or smelly (and it doesn’t as long as it’s been kept dry)—just that it loses its structure.

So while you can still use old seed starting mix or potting mix past its “expiration,” you’ll likely have to replenish the peat to maintain its water-holding capacity.

Can you reuse seed starting mix or potting mix?

You can reuse seed starting mix or potting mix as long as you didn’t have any problems with pests or diseases.

Let the old seed starting or potting mix dry out before storing in a bucket, storage bin, or clean trash bin, and keep it dry until you’re ready to use it again.

You’ll likely only get one reuse before the quality of the seed starting or potting mix is diminished, since one of its main ingredients, peat moss, is a natural fiber that breaks down over time (especially if it’s been wet).

What can you do with old seed starting mix or potting mix?

Old seed starting and potting mixes that need to be rejuvenated can be mixed in with new soilless mixes to give them a second life. They can also be added to your garden soil to help improve soil structure. (In either case, just make sure they’re free of any pests or diseases so you’re not introducing problems to new plantings.)

But if you don’t plan to reuse your seed starting or potting mix, you can just add it to your compost pile and let it break down naturally.

Do you need to sterilize seed starting mix or potting mix?

I don’t recommend sterilizing your seed starting or potting mix because it puts your seedlings and plants at a disadvantage from a biological standpoint.

Sterilization kills all bacteria—both good and bad. Without these microbes providing natural checks and balances that weed out weak plants and strengthen the healthy ones, your plants—which have been coddled in a “perfect” sterile environment inside your home—become unable to fend for themselves once they’re out in the garden.

3-Ingredient Organic Seed Starting Mix

The best DIY seed starting mix has only 3 ingredients. Save money and get my no-fail recipe for organic seed starting mix you can easily make at home.

Materials

  • 1 part sphagnum peat moss (or coco coir)
  • 1 part perlite
  • 1 part vermiculite

Tools

  • Clean tub or bucket

Instructions

  1. Combine all the ingredients in a clean tub or bucket, and saturate the mix with water.
  2. 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.
  3. 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.)
See also  Ph For Germinating Weed Seeds

Notes

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.

Did you make this project?

Please leave a comment on the blog or share a photo on Instagram

Where to buy seed starting mix

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

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 »

81 Comments
Amar Choudhary
Ken Long

Do you add any lime to the seed starting mix?
The base mix by itself comes out very acidic, about 4.5 ph. just like the peat moss. Compare this to the Espoma Organics seed starting mix, which is just peat moss, perlite, and lime, at about 6.5 ph.

Linda Ly

Did you have the base mix tested to determine the pH? In my experience, peat moss does very little to acidify soil (in seed starting mixes or in garden soil). The pH is acidic to start (when peat is first added) but neutralizes after about a week of being watered, and most seeds don’t germinate until then. So there’s no need to add lime to seed starting mix. I’ve yet to find any ag studies that support the common belief that peat is an effective acidifier by itself.

Gene @The California Table

wow, this is an especially informative discussion of seed starting mix (and some good info on potting soil mix, too), thank you for all the education!
I wanted to add that many gardeners are finding that coir has such a high salt content that seedlings fail to thrive in mixes made with coir. Recently, a company in Pittsburgh started offering PittMoss, a soil-less planting mix. Their product “Plentiful” seems to work well. Using it is a little bit of an adjustment…it looks lumpy but it IS light and fluffy and it doesn’t change color much when it’s wet (so I have to be careful to water enough and not too much).
It’s all recycled paper products and sold in approximately 2 cu ft bags, online.
Tho the Canadian Peat Moss Association is succeeding at farming peat sustainably; there is this demand for seed starting mix that does not use peat, so PittMoss may be the first, but probably not the last, company to figure out how to reuse waste paper:) I love innovation!
Hope this helps as we all make our own decisions (as Garden Betty carefully reminds us is our own responsibility) based on the best information we have and our own best intentions. Happy Gardening!

Linda Ly

Great info, thank you Gene. I hadn’t heard of PittMoss but that sounds like a promising alternative, or at least another option people can try and see if they like it!

Gene @The California Table

I should have also stated that in San Diego, diy mix cost about the same as commercially available seed starting mix! Prices are just so high here, on everything; so, this year I planted some seeds in commercial mix and others in the paper-based product I mentioned. All of my seedlings took off, doing great:) Except some seeds that were a gift and from a seed company I haven’t ever bought from, so…. when you find high performing seeds, stick with that company:)

Helpful site – however, just wondering why you recommend peat when it is a non-renewable resource that sequesters carbon and harvesting it destroys habitats which take hundreds if not thousands of year to grow back?

Linda Ly

Hi Anne, I’ve answered the peat vs. coco coir debate a few times in the past if you scroll down a bit in the comments, but I’ll copy and paste one of my previous responses here:

If you read my post in its entirety, you’ll see that my seed starting and potting mix recipes both offer coco coir as an option if you can’t find or don’t want to use peat moss.

I know some people prefer coco coir over peat moss because it’s thought to be better for the environment, but truth is, coco coir requires quite a bit of processing. Even though the material itself is made from a waste product, the processing produces more waste products and has other detrimental effects on the countries and industries where it’s made. Not going to argue over which product—coco coir or peat—is more sustainable, as they both have pros and cons.

All that to say: peat is perfectly acceptable to use from an environmental standpoint, especially if you’re just using it to pot up plants, and not en masse as a soil conditioner. Coco coir is far from being the eco-friendly alternative it’s claimed to be, and there is little evidence to support that claim.

You’re always welcome to do your own research and draw your own conclusions on this, based on what your personal definition of sustainability is.

Suella

HI Linda – thanks for this recipe. As it has no nutrients in it, at what stage do you report the seedlings so they start to grow? My experience is that my seedlings sit at the 2 cotyledons stage, and I’ve concluded that they need nutrients to grow on. Am I right?

Linda Ly

You should repot the seedlings once they develop a few sets of true leaves—by that point, they’ve used up their nutrient stores.

Samantha

Hi Linda When you say to replenish the peat for old seed starting mix, do you mean I should buy peat and mix it in? If I just keep putting more of the seed starting mix in the cups once the seeds germinate does that count as replenishing the peat? Or could I just mix my new seed starting mix with my old one. (FYI my old mix is from 9 years ago.) Many thanks for your help!

See also  Fruity Weed Seeds
carole otness

Thanks so much for your post. Great info.
One thing that may have not been mentioned in the replies is the harm that our using peat moss does to the planet. We (USA) get most of our peat moss from the bogs of Canada. We need to be preserving these bogs as they are crucial to keeping the balance in nature.
I will be trying your “recipe” using the coco coir.
Thanks again, best wishes to you,
Carole O.

Steve

Useful post! I’m thinking of trying the seed starting mix recipe shortly (the coco coir version).

I have a question though – with the 1:1:1 ratio of coir/vermiculite/pearlite, does the one part coir refer to dry coir or hydrated coir? That is, should I be wetting the coir before measuring it for this recipe? I’m a bit confused here, because most of the other recipes I’ve seen seem to use a far higher ratio of coir (like 60-70% of the total volume, at least).

Ellen

Hi, I’m starting seeds indoors for the first time and feel like I’m missing a step, when do I move seedlings from the little containers with starting mix to larger containers with potting soil?

I am a gardening beginner. I wonder if I can add some crushed egg shell into the basic seed starting mix, or moist the mix with boiled egg shell water? Just in case I transplant the seedlings a little late and they need some nutrient…?

Can You Grow Cannabis with Miracle-Gro Soil or Nutrients?

Miracle-Gro Slow Release Soil is Not Suited to Growing Marijuana!

Many of us have grown up seeing Miracle-Gro being used in our homes, so we know that it works for ‘regular houseplants’. Cannabis is just a tough weed, so Miracle-Gro should be great for it, right?

The biggest problem with the standard Miracle-Gro nutrient formula is that it’s one formula for the entirety of the plant’s life cycle. Even if the standard Miracle-Gro plant food is decent for the first stage of your plant’s growth, it won’t be good for the budding/flowering phase. The ratio of nutrients your plants need changes drastically between seedling and full flower. Marijuana grows best with a nutrient system that accommodates their changing nutrient needs.

Avoid Miracle-Gro Soil for Growing Weed!

Do not use “Miracle-Gro” soil or any soil that has “extended release” nutrients for growing cannabis. These types of soil will continue to release nitrogen to your plant roots for up to 6 months. This can cause deficiencies or burn your cannabis plants in the flowering/budding stage, reducing your overall yields. I have seen growers successively grow cannabis in Miracle Gro, but many of them struggled with nutrient problems in the flowering stage (like the following) even though plants were healthy throughout the vegetative stage.

What’s worse than the standard Miracle-Gro nutrients is the original Miracle-Gro soil. Standard Miracle-Gro soil has “time-released” nutrients which contain high levels of nitrogen. While this formula will work okay in the cannabis vegetative stage (the first stage of life), the nutrients will continue to be slowly released throughout the plant’s life including during the cannabis flowering stage, which is not good.

Standard Miracle Gro nutrients contain too much nitrogen and not enough of other nutrients for your cannabis flowering stage, and as a result of the time-released nutrients, you will notice that your leaves in the flowering stage will get nutrient burn and your buds just won’t grow as big as they could. Learn what you can do to make sure buds grow as big as possible!

Important: Do not use “Miracle Gro” soil or any soil that has “extended release” nutrients. These types of soil will continue to release nitrogen to your plant roots for up to 6 months. This can burn your cannabis plants in the flowering/budding stage and reduce your overall yields.

There’s nothing inherently wrong with Miracle-Gro nutrients, and if you’re willing to learn about nutrients, you can use the various different formulas and get a cannabis plant to grow. For example if you’re using regular soil, you could use the standard Miracle-Gro formula for vegetative, and their “bloom” version for the cannabis flowering stage.

Yet there are so many nutrient systems that are specifically formulated to grow a plant like cannabis. Why not choose to get better cannabis nutrients that will almost always produce better results? Some options like Dyna-Gro are priced about the same as Miracle-Gro nutrients, but you will consistently get bigger yields and more flavorful buds.

Miracle gro seed starter mix

So I bought a bag of miracle gro seed starter mix. It’s just peat moss, so I thought. I germinated 2 seed, paper towel method. when they sprouted a tap root, I put them into solo cups with a 50/50 mix of perlite and seed starter mix. Both of the seeds made it to the top of the soil then stopped before the husks came off. And they just stayed there. So, being the curious person that I am, I gently pulled the seedlings out of the medium. They came right up. No resistance at all! When I looked at the tap roots, the ends were curled up and did not look happy. Now I was really curious, so I looked at the bag of starter peat moss, and low and behold, the stuff is enriched with miracle gro food. So this just leads me to believe that the SEED starter “mix” is too hot for the seedlings. WTF. has anyone else had any experience with this stuff? I have 2 more seeds germinating now and they will be going into a 50/50 coco/perlite mix this time. I already have 2 in there that just started veg. About 3 weeks old and started the training on them last night. These two were started in used/depleted soil, basically inert soil. so there was no way they were going to burn. Now they are in miracle gro cactus, palm, citrus mix at about 70/30 soil/perlite and happy as heck! The food that is in this mix isnt the “feeds for 6 months” stuff. Just enriched with the nutients outa the bag. And the ratio is 0.6-0.2-0.4 so half of that is 0.3-0.1-0.2 which is found to be the optimum ratio for cannabis (3-1-2 or so I have read)

so far under 4 x 32.5w cfl 2700k 2600lm each and 1 x 23w (I think) 5000k just for spectrum diversity and 20/4 light schedule. I have 4 more 32.5w bulbs for flower.