I make my own seed raising mix, mostly as I hate carting heavy bags of ready-made stuff, I love making my own, it’s cheaper, and, last but not least, I know what’s in it.
I stock up on blocks of premium grade coconut coir (also called coconut peat) ahead of the seed raising season. They are a waste product from coconut farming that is upcycled and put to good use. They’re light, stack neatly in the nursery and the plastic packaging is much thinner and smaller than those of ready-made seed raising bags. It has however a large carbon footprint due to being imported from Sri Lanka or about… I console myself knowing that I use it to grow food, cycle nutrients, improve soil structure, etc…
Look for coir bricks that come without added synthetic fertilisers or water crystals. The type I get makes up to 9 litres.
Then, in the seed raising mix go worm castings and worm wee. I know where these come from… one of our many worm farms!
Then comes vermiculite, a natural mineral which helps with moisture retention and drainage. It is a mined product, potentially from America (although I am checking that with the brand where I buy it from and will write back once I know). Again, I have the ethical dilemma regarding the use of this product because of its carbon footprint…. Sigh! It’s not easy being 100% green I tell you!
I mix three parts coconut coir (that needs to expand with diluted worm wee), one part worm castings, one part sieved homemade compost, and one part vermiculite. Voilà! Ready to use for raising even the tiniest of seeds or taking cuttings.