Q&A – Why do most Commercial Potting Mixes have Fertilizer in them now?


Janice H. asks Annie:

Q  How do we get the manufacturer’s to stop adding fertilizer to potting soil and peat moss?  I’ve had a problem in the past with the roots of my AV’s being burned from the unknown [at the time] added fertilizer.  You and Joyce Stork were so helpful in letting me know that Espoma AV soil had added fertilizer that was not noted in the ingredients list.  Recently I went to my local garden center in search of buying plain potting soil along with peat moss and perlite.  Much to my disappointment nothing was available without added fertilizer in different forms.  I made my quest known to the greenhouse manager, but I was told that that was how the people want to buy their soil.  They do not want the added responsiblity to fertilize their plants.  My question to the manager was how do people who grow for show handle potting their plants?  She had no answer for me and was actually a bit short with me for bringing this up.  The solution to my problem was to buy a bag of Scott’s Top Soil.  It has added humus, but no fertilizer.  And this was a tip from the salesperson.  He said his grandmother pots all of her indoor and outdoor pots using top soil.  She is then able to fertilize on her own schedule.   I don’t mind buying the large bales of potting soil and peat moss at the garden center, but it sure would be nice to be able to have more manageable sized bags to store.


A  Janice, this is great question.  Unfortunately, we really don’t have much control over how commercial companies package their mixes.  The majority of African violet growers do not grow for show, and most people do seem to prefer soil and/or perlite with fertilizer already in it for their houseplants. I can tell you that a number of African violet growers use these types of commercial mixes – usually cut with perlite – very successfully.  I am currently using MiracleGro potting mix cut 50/50 with perlite for Rhapsodie Annie, which is growing well in a self-watering pot in natural light in my sunroom.

For my show plants, I use SunGro’s Sunshine Mix #1, which does contain some nutrients, but they are more incidental than anything else.  I am a little concerned about the topsoil you purchased as it specifies that it contains organic matter and that it’s not for use in container gardening – so, once again, I checked in with Joyce Stork.  Here’s what she said:  ” As to helping her find better ingredients to mix her own, I would suggest avoiding the big box stores with untrained staff helping the average person who knows little about chemistry. Instead go to a hydroponics store where the staff is quite prepared to sell to educated discerning growers. Of course, their primary customer grows cannabis, but they have the top of the line soil components and growing supplies.”   I hope this helps!


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