EVALUATION OF POTTING SOIL VERSUS HALF SOIL HALF COMPOST FOR CONTAINER VEGETABLES

Today I want to talk about healthy soil medium especially for container planting.  I am the "soil girl" and have a great affinity to the science of soil and soil medium.  I also believe in experimenting and allowing my creativity and intuition to guide me along with scientific information.

I have been researching soil medium for container vegetables especially.  Almost all information suggests using potting soil as the soil medium, add a little Osmocote perhaps and you will have great results.  So, I used the potting soil with the Osmocote for my cabbage and zucchini plants along with my tomatoes this year.   Container vegetable success is not only related to a well draining, light, organic mixture but also to the type of roots:  short, long, vertical, etc.  Roots, I believe are key to success with container gardening...how deep to they grow; how long are they; do they expand down or horizontally,etc.   I am finding that if roots are long such as with the zucchini, they grow poorly in containers.  Tomatoes also have relatively long roots and so container gardening for the larger plants isn't the best choice.

So, here is what happened for me:  the zucchini "puttered out" in containers and gave me one zucchini that grew to about six inches and stayed there for over a month.  All other zucchini plants in containers died even with side-dressing with compost several times.  We had a lot of rain this spring so these plants got the water they needed through rain or manual watering.  My tomatoes are not growing the abundance of leaves that they usually do when in the ground and I still am getting the blight that I get every year with soil planting of tomatoes even with compost side-dressing.  Time to evaluate if potting soil is appropriate for "heavy feeders" with some of the vegetables.

One of my conclusions is that there is not enough nutrition in the potting soil with 1/3 peat moss, 1/3 compost and 1/3 vermiculite which is recommended for container planting.  Next year I am going back to my 1/2 soil and 1/2 compost with side dressing every two weeks as was done last few years.  There is such a marked difference between my container vegetable plants this year and last year.  Good to experiment but think I'll go back to a soil medium heavier on the nutrition and compost side. 

 2012

 2012

 2012

2012

2013