Potting Soil Comparisons

I came across this fantastically in-depth potting soil comparison the other day. It's too bad he only used one organic soil, as I'd much rather see how various organic soils fared with one another. Nevertheless, I'm impressed by his thoroughness! Here's his conclusion:

Supersoil's high germination rate and superior growth in both melon and tomato seedlings make it the preferred choice of the potting soils tested. When the additional factors of ease of handling, easy watering, fast drainage and low cost are also considered, it is the clear winner.

Peaceful Valley Farm Supply's potting soil came in a close second. But, the fact that it's four times the price of Supersoil after adding in the cost of shipping and not conveniently available makes it much less desirable. Another downside is that it contained weed seeds that germinated in the sample I tested. This was an annoyance that could be a serious problem for someone whose desired seedlings looked like the germinating weeds. How would he or she know which to remove?

They are many dozens of other potting mixes on the market that I wasn't able to test so this experiment can't be considered definitive. But, it strongly suggests that Supersoil potting soil is a superior product capable satisfying anyone's gardening needs. It's certainly the brand I'll be using in my garden from now on.
 

And here's a final note of warning that he makes about a horrible brand he used the year prior. Funny enough, this is the potting soil that I've been using (not the rose one, but the vegetable one). Yipes!

The year before the above comparison I purchased four bags of Gardener and Bloome's Rose Potting soil and used it to plant 77 pots with zinnia, tomato, melon, Canterbury bell and salvia seeds. The results were a complete disaster. Although I followed my regular routine for growing seedlings, a routine that's worked flawlessly for over 20 years, with this brand of potting soil I only got a 20-percent germination rate, the few plants that came up grew poorly, exhibited many disease symptoms and 30-percent of them died. Upon testing the soil I discovered that in spite of the package advertisements stating that the soil contained a wide spectrum of organic amendments such as bat guano, worm castings, kelp meal, alfalfa meal and so forth, the soil was completely lacking in nitrogen, potassium and phosphorous. Even after adding extra fertilizer the plants grew poorly. I've used many potting mixes over the years and this is clearly the worst. Perhaps I got a bad few bags out of what may otherwise have been a a good production run, but for myself I will never use this product again.