Seed Starting Mix: A Recipe To Make Your Own

Starting your own plants from seed, whether edible or ornamental, is 1 of the most satisfying things a gardener can do. And, you can get a head start on the season by putting your seedlings in the ground once the weather warms. It’s important to have a good seed starting mix and even better if you make your own.

This is a soilless mix, which is what you want for seed starting. It’s very light and well-aerated so those tiny plants can easily emerge. 

Note: This mix can also be used as a propagation mix for cuttings. It works great for stem, leaf, softwood and tip cuttings because the roots can easily emerge and grow into it.

I don’t start much from seed anymore (I live in the Sonoran Desert) except for the arugula I grow every winter. My new kitty Sylvester, who I adopted from the Humane Society of Southern Arizona 2 months ago, has taken a shine to my Spider Plant which sits on a low plant stand in the bedroom.

a  large tuxedo cat lays on a rug & looks into the camera

Fortunately, he doesn’t chew on any of my other 45+ houseplants but because he’s an indoor kitty, enjoys a daily chomp on those crunchy Spider Plant leaves. This prompted me to buy cat grass seed mix seeds which germinate quickly and grow fast.

I’m starting with 2 – 4″ pots and will see how he likes the grass. I may be germinating it in constant rotation so this mix will most likely get a lot of use. Stay tuned cat lovers – I’m doing a separate post and video all about growing cat grass.

The ingredients for this seed starting mix are very similar to the succulent and cactus mix recipe I shared with you a few months back.  So if you made that, you’ll only need 1 extra ingredient (perlite) for this.

I bought all my ingredients at Eco Gro (a place for we plant aficinados) here in Tucson.  I list the same or similar products but different brands which you can find online below.

bags of ingredients used to make seed starting mix sit next to a trowel & a metal bin

The ingredients next to my metal mixing bin.

Seed Starting Mix Recipe

Elemite can be hard to find online – I buy it in-store at Eco Gro. Azomite is similar in that it’s also a mineral rock dust & makes for a good alternative.

What you use for a scoop is up to you. Just follow the proportions. At Eco Gro they use a good-sized soil scoop which is approximately equal to a large yogurt container. I used a good-sized bowl in the video.

Peat moss is often used in seed starting mixes but I prefer coco coir. It’s a much more environmentally friendly alternative and if you’re interested, can read more about that here and here.

The coco brick, or portion of it, needs to be hydrated prior to using; usually a couple of times. It expands and becomes fluffy after hydrating – you can use it damp or dry. There’s no need to hydrate again when using it in this or other mixes.

This recipe isn’t something I concocted. The original comes from Mark A. Dimmitt who is local and very well known in plant circles. He shared the formulation with the folks at Eco Gro and now I’m sharing it with you.

See the mix being made!

How Much Does it Cost to Make One Batch of this Recipe?

I bought all the ingredients locally. The cost may vary for you depending on where you purchase everything. Even though I made 1/2 the recipe, I calculated this estimate using the full recipe. And, there are plenty of ingredients left over to make more batches.

Approximate cost: $6.50

I used old 4″ grow pots to start the cat grass. If you’re new to this, there are hundreds of seed starting trays on the market along with a multitude of biodegradable seed starter pots.

Here are tutorials on using toilet paper rolls and newspaper if you like to craft your own.

A bit about each of the ingredients

Coco peat or coco fiber comes from coconut husks & is a sustainable alternative to peat moss. It’s very light, holds water & is beneficial for roots.

Perlite aids in drainage & lightens any mix.

Vermiculite absorbs moisture & aerates.

Ag Lime is crushed limestone. It promotes healthy growth.

Elimite (& Azomite) stimulate root growth & overall health.

a large metal bin filled with diy seed starting mix sits next to a 4" grow pot

Good to know about this seed starting mix

This recipe keeps; especially when kept dry. If you don’t use it all in 1 go round, you can save & use it throughout the year or the following season.

It’s excellent for propagating as well as starting seeds. 

It’s very dry so be sure to thoroughly wet the mix in your pots or trays before planting the seeds. 

If you do a fair amount of seed starting or propagating, this mix saves you money. 

As I said above, I don’t grow much from seed anymore. But that doesn’t stop me from looking at seed companies online and wishing I did!  A few of my favs are Baker Creek, Territorial Seed Co, Seeds Of Change, Renee’s Garden, Sustainable Seed and Botanical Interests. When it comes to flowers, Floret Flowers really is a treat for the eyeballs.

Gardening season is right around the corner – it’s a great time to give this mix a try.

Happy gardening,

Signed by Nell Foster

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