A DIY Seed Starting Soil Mix Recipe
If you want to start a garden from seed, it is very important to choose the correct soil medium for starting and raising those seeds. Using a good seed starting mix will improve your chances of success. Now, you do have some choices, but it’s important to not feel overwhelmed and just go for it! Read on for my DIY seed start mix recipe.
You can skip this article all together if you A) want to direct sow your seeds and B) the weather and conditions look right for directly sowing your seeds in the garden
You can read about the pros and cons of direct sowing versus transplanting from seed pots HERE.
What Are Some Choices For Seed Starting Mixes?
1) Pre-mixed bags
There are some wonderful companies out there selling seed starting mixes that are ready to go! These are a wonderful option if you are looking for an efficient way to start a small amount of seeds. One of my favorites is a mix from Epsoma and for convenience I’ve been picking up this Jiffy Seed Starting mix from Home Depot. Simply fill your trays or pots with your seed starting mix and you are ready to go!
Most commonly, you’ll see peat pellets at your local hardware store or nursery. These little discs expand into individual soil pellets when you add water to them. All you need to do is add your seeds and keep them moist. These pellets are wonderful for beginner gardeners. When Sam and I first started gardening, we used pellets with great success. They are also small-space friendly. Eventually, as our garden grew larger, our need to start more seeds made it most feasible to make our own seed starting mix using bulk ingredients.
Here are some examples of pellet kits that are great for small spaces:
12 Pellet Greenhouse Kit -great for windowsills, starting a few seeds
36 Pellet Greenhouse Kit – You’ll notice the pellets are larger in size (50 mm). I do find these larger pellets more convenient sometimes because plants can grow larger without needing up-potting.
3) Soil blocks
This method requires a soil-blocking tool like this one. There are a lot of benefits to using soil blocks—-such as no need for plastic pots/trays and less transplant shock. If you plan on using soil blocks, you’ll have to follow the directions for a specialized seed starting mix that will hold together—you can’t use my mix recipe. Instructions usually come with the tool, or you can find videos on YouTube.
4) DIY Seed Starting Mix
This is currently our preferred method. We buy large bags of each ingredient at our local nursery and can keep them on hand for mixing when we need it. Our original recipe lists peat moss, but it is very easy to make the mix peat-free. If you would like to make a peat-free seed starting mix, simply substitute coco coir in place of peat moss. *The only change is that you’ll need to pre-moisten the coco coir (per package instructions) in order to break it apart for mixing.
If you are using a DIY seed start mix, you’ll need to choose seed trays or pots to grow in as well. Personally, I used to struggle to find good quality seed pots for starting—so many crack or get crushed after one season—but now I use Epic 6-cell or 4-cell trays and LOVE them. They are durable, rigid, and will last for many years!
Calculate the approximate amount of seed starting mix that you’ll need. Tip: Do not make more than you’ll use right away. Only make seed starting mix as needed.
Wear a mask and safety glasses and do this outdoors *see additional notes below
Start by mixing together equal parts peat moss (or coco coir) and vermiculite. For example, if you want to make a 5 gallon bucket of mix, fill half the bucket with peat moss and then add an equal amount of vermiculite. Tip: keep in mind that you’ll need space for mixing, so leave room in your container to mix all the ingredients together.
Sprinkle starter fertilizer. I never measure, but just do a light sprinkle over the whole thing. This is even an optional step! You can feed your seedlings once they have already germinated, instead of adding the starter fertilizer. I personally do both types of feeding and made a video of How I Feed My Seedlings after they have germinated and started growing.
Moisten the mix with water. My biggest tip for using any seed starting mix it to pre-moisten it. This allows us to simply plant our seeds and not have to worry about watering them afterwards—which can sometimes lead to flooding the seeds out of the container or other similar disasters.
Watch My DIY Seed Starting Mix Video Tutorial
Additional Notes & Tips
Remember not to make more than you need right away. Seed starting mix doesn’t keep well, and by leaving it for later you are inviting gnats or other problems into your mix.
Pre-moisten! The mix should stick together slightly when squeezed in your hands, but not leak out tons of water. Don’t make it too soggy!
Don’t inhale the small particles as you are mixing. The dry vermiculite and peat moss contain really small dust particles that can be bothersome. I sometimes wear a mask and definitely work in a well-ventilated area. Moistening the mix does help keep the particles at bay—so feel free to add water as you go along.
⇓ Do you plan to start a garden from seed? What are some of your experiences or questions about this process?⇓