Anniemae: Although adding perlite to any garden soil works fine, I find I don't have time to do it. I have planted over 100 containers for each of the past two years, so I buy the sterile planting medium, which already has perlite or some other such thing added to promote good drainage. I have on occasion bought bags with fertilizer added, so there's no need to fertilize until planting out time. For me it's just a matter of how much time and space I have to devote to winter sowing. You have taken the time to find something that works well for you and produces healthy seedlings. Thanks for sharing.

I use Miracle Gro. Had one funky bag, otherwise all is well.

Whatever it takes to have fluffy "soil," that's the key. I bought a bag of Hyponex my first year wintersowing, and adding perlite didn't seem to help. I think I should have let the soil dry out and added peat moss instead. I still got sprouts in that brick of soil, but they stayed tiny until I eventually planted out.

I saved my containers from my first year (quite a lot of people don't save containers) so I used that extra time for mixing up my own wintersowing mix. It's the cheapest way I can have lots of nice fluffy mix, since I buy perlite and peat in bulk. I also add garden soil, compost, and aged horse manure. My seedlings sit in the container for months, sometimes, so I want there to be 4-5 inches of mix, and some nutrients in there.

For any newbie deciding on what to do for their wintersowing "soil" mix, our seed-starting mix doesn't need to be sterile, although many times the product we buy is. Fluffy is the key word!