It can be overwhelming to shop for seed starter mix, and what to use. Big-box stores are full of tiny bags at high cost, while plant nurseries offer small and large bags, even more expensive.
But it doesn’t have to be. In most cases, it is only 2 to 3 ingredients, easily done in a day, and you have full control over it. It is usually peat moss, coconut coir, and perlite. Some brands add in mild plant food or lime to balance out the moss/coir. If all you are starting is a couple of trays of seeds, then prebagged might be better, but if, like me, you have many to start, making it from scratch is usually a better deal.
For example, this “seed starter mix” is actually nothing but coconut coir, which you can buy in larger quantities for far less. While it will work, you will need to feed your seedlings sooner or later, and perlite helps with drainage.
Now then, coconut coir has become the go-to, and peat moss is being used less. The argument for this is that peat moss is limited. We will eventually run out of it. Coconut coir is a recycled waste product from the vast number of coconuts used annually. If anything, it is preventing a lot of garbage. However, it has its own issues: not every brand sold is prewashed, and it can be salty (it is processed using ocean water). If the package you buy doesn’t declare that it is washed, I highly recommend soaking and draining it at least twice before using it.
Most coconut coir is sold in compressed blocks, making it easy to purchase and carry. You will need a tub to place the brick in, then soak it in water. After it sits for a few minutes, you can scrape at it with a hand shovel, then add more water and repeat. Once it is finally all fluffed up, then add your other ingredients and mix well. Just store it out of the rain if you keep it outside for best results.
Having a dedicated soil tray makes gardening happy. While they exist and are sold at large garden centers or online through greenhouse companies, you can make one from concrete mixing pans/tubs. bought inexpensively at hardware stores. I keep two around, in medium and large, bought at The Home Depot for $8 and $17. I had a dedicated greenhouse tub that came with our greenhouse, and it was far more fragile and bit it after a couple of years, developing cracks. The concrete tubs keep going.
DIY Seed Starting Soil Mix
Ingredients:
- 2 parts Coconut Coir or Peat Moss
- 1 part Perlite
Directions:
If using coconut coir, place the brick in a water-tight mixing tub (see above) and soak it in water, then scrape the brick as it hydrates, adding more water as needed, until the entire brick is fully hydrated. If the coir isn’t labeled “prewashed,” you will want to soak it, then drain, and repeat once more.
If using peat moss, add water as needed to fully hydrate. It will take far longer than coir does. Be sure to break up clumps and work it into a fine powder.
For both materials, it should be the moisture content of a wrung-out sponge.
Add in the perlite and mix well.
Now start filling your pots and get seeding your future garden.
~Sarah