Going out to the store and buying a perfect mix, probably with an exact correct slow release fertilizer is lovely and efficent and reasonably priced when you consider what we pay for plants and pots. Its definately the right way to goo. But, when you're finally good at keeping them alive and happy, you have the water and the light just right and your collection is now hard to count, and cubic ft packages become necessary.. it's time to DIY a dirt recipe
