And if you have to both sterilize and amend the substrate to make it work for starting seeds, why not just make life a little easier and start with a mix intended for the purpose?
Also, how sure are you that your backyard topsoil doesn’t contain weed seeds?
These will be difficult to kill to prepare the soil for use as a growing medium for propagation, since some weed seeds only die after spending seven days at temperatures of 180°F or higher.
Because of the difficulty of maintaining that temperature at home to alleviate the risk of weeds, using a readymade seedling mix is a much easier option.
Are Seed Starting Mixes Best?
While commercially available potting mixes can be used provided they are sterile, the lightweight media in soilless mixes formulated for seed starting enables tender roots and shoots to emerge easily.
It also makes transplanting easier.
I prefer to use soilless seedling mixes for this propagating seeds – but I always look for those free from peat moss, a gardening ingredient with heavy environmental baggage that is being banned in the European Union and the United Kingdom.
One of my favorites, Rosy Soil Seedling Mix, includes ingredients such as biochar, sand, compost, and worm castings.
Rather than providing a sterile option, Rosy’s Seedling Mix contains beneficial mycorrhizae to help young plants get established.
Rosy Soil Seedling Mix
Want to give it a try? Rosy Soil Seedling Mix is available for purchase in eight-quart bags via Walmart.
And there are other great options especially designed for maturing plants as well!
If you’re low on space and prefer sterile ingredients, you can also use coconut coir as a propagation medium.
You can find coconut coir in packs of two concentrated space saving blocks from Burpee.
Concentrated Coconut Coir Blocks
You just need to add water, and each block will expand to eight quarts, ready for use.
Since coconut coir isn’t a nutrient-rich substrate, be sure to fertilize young plants regularly with a suitable food.
When to Use Specialty Mixes
By now, you’re probably thinking that growing mediums specifically formulated for propagating seedlings are the best choice.
But there are exceptions!
