Hello, I am fairly new to organic gardening, and this year I tried developing my own fertilizer blend for general-purpose fruit and vegetable container gardening (strawberries, cherry tomatoes, peas, and green bush beans). However, after much careful research and effort, I was informed from a salesperson at a garden store that my special fertilizer blend may be deficient in potassium.
My fertilizer blend is composed of bone meal (Whitney Farms, Organic, 3 lb. bag, 6-8-0), blood meal (Whitney Farms, Organic, 3 lb. bag, 12-0-0), and kelp meal (Dr. Earth, 2 lb. bag, 1-0.5-2). I also added 4 dozen powdered eggshells (dried at 200-degrees for several hours), and about 2 cups of Epsom salt (I understand that magnesium sulfate helps with blossom production). I have amended the soil with store-bought compost ("Black Gold" brand; N-P-K unknown), and I am going to add worm castings from my own worm bin.
I was preparing to add dried, powdered banana peels for more potassium, but I was informed that this may not be a valid source of potassium (apparently it is an "old wives' tale").
I accessed an article on Oregon Extension website which described the N-P-K values of organic fertilizers(http://extension.oregonstate.edu/lane/sites/default/files/documents/lc437organicfertilizersvaluesrev....
I am very interested in "cucumber peels (burned)", as this article proclaims that the estimated N-P-K value of this fertilizer is 0-11-27. However, I am not clear how to properly create burned cucumber peels, in what amount to apply per square foot, and most importantly, whether this particular fertilizer presents a risk of harm to my garden when added to my already amended containers.
So, after all this explanation of my particular predicament, I would like to know if there are alternative, perhaps "safer" organic options for adding potassium to my garden, or would burned cucumber peels be a good solution?
Also, am I misunderstanding the importance of a "balanced" fertilizer? What I mean is, do I have to aim for a fairly equal ratio of N-P-K values, or is it sometimes ok if one of the values is a higher proportion than the other components? (For example, in my situation, I am estimating that if I were to add burned cucumber peels in the correct proportion to my current fertilizer blend, the N-P-K values would roughly be increased from 19-8.5-2 to 19-19.5-27. Would this be a safe or desirable balance for general fruit and vegetable gardening?).
Final question: I have heard varied advice about how best to apply worm castings to potted plants. I have previously allowed the castings to dry out, as this seems to encourage most of the insects from the ecosystem to vacate the castings (which I imagine is in the best interest of the plant). Is this best practice when applying worm castings, or would it be better to apply the castings straight from bin to plant?
Thank you for any advice you can offer me! Have a beautiful day!