Yes, you're absoulutely right (I understood that you meant Light Mix?).
Furthermore, I have to moderate my previous post. Thought I've mostly have used All Mix 'till now, I have found that I save a substantial amount of money making my own mix, with similar results:
Approx:
- 50% good quality organic potting mix with sphagnum peat moss, limestone meal, sand, clay, dolomite, minerals and micro-nutrients, as well as N-P-K. (over 400 kg/m3 = heavy).
- 10% Biobizz Wormcastings
- 10% Perlite
- 10% Vermiculite
- 20% Cow manure compost
- 2-3% Biobizz pre-mix
- beneficial fungi and bacteria
- GHE Mineral Magic
For seedlings, clones and 1st transplant, I use a specified, low-fert seedling-soil instead of pottingmix.
The cost of this is well under half of the finished All Mix-product. But, by all means, it's very good IMO.