Seedfork said:I think the main reasons most mixes avoid real soil is due to the drainage and disease and insect problems when they are placed in pots. I feel that a little garden soil is OK, I use some in my mixes and have so far had no problem, but it is a very small amount I use in the mix. When I dig some of my compost for the mix, I make an effort to always get some of the soil mixed in with it, often in an attempt to catch some of the worms. The soil added in my mix replaces the sand actually recommended. I don't think I would add garden soil if it was clay, but I have very little clay soil anywhere on my property. Fine pine bark is the main ingredient of my mix and I love it. I buy it by the pickup truck load. How much compost and soil I mix in just depends on exactly what I am doing with the mix, for just potting up daylilies it probably varies from 75 to 90 percent fine pine bark.
thommesM said:Potting mix... what are you going to use the potting mix for? Just want to be clear. If you are talking about for starting seeds, as Larry mentioned, I'd be careful about using soil from any source that hasn't been sterilized. I regularly lose brassicas due to damping off and not sterilizing the soil is one of the largest issues. If you sterilize the soil, I don't see why you couldn't use some top/garden soil in the mix.
If you are talking potting mix for planters, I make my own. If the container already has soil in it from previous season, I'll dump it into a wheel barrow and add compost from my pile, or compost that I've bought for the season, or typically a little of both. That's the mix I use. I don't really add any soil.
I'll mention this warning. I was trying to be more sustainable and use coconut coir as an ingredient in my seed starting/potting up mix. First year I lost a ton of plants and someone suggested the coir had too much salt in it. I tried to buy a meter but it came DOA. I rinsed the coir this last season four or five times then used it as an ingredient, and I still lost a lot of plants. I am going to swear off coir, though it was the same coir that I used the previous year. If someone has had good luck with coir, I'd like to hear about it and the brand that you used.