My suggestion would be to dump out all the containers and start over with decent potting soil - something very comparable to the 5-1-1 mix referred to here frequently.

One of the many mistakes container gardeners make is to assume that container soils will act similarly to inground soil. They won't :-) Things that work well in the ground - compost, manures, allowing roots or other plant parts to rot and decompose in place - just simply will not work well in a container. If anything, they will impede good drainage and contribute to lack of proper aeration, elements which are critical to growing in containers but have much less of an impact in natural or inground soils.

I am making an assumption from your posting that you are attempting to be pretty organic in this process. Growing organically in containers, at least as far as fertilizing is concerned, is difficult to do. There are few organic ferts that are fully water soluble AND that offer a full range of plant nutrients including the micros. And granular or non-soluble organic ferts require significant populations of soil microorganisms to break them down into plant usable forms and these are just not present in any quantity in a good quality, soil-less potting mix. The fish emulsion is decent, the molasses may add some benefit but needs to be thoroughly mixed with the liquid organics and Epsom salts isn't a fertilizer at all unless you have a magnesium deficiency - The Myth of Epsom Salts.

I'd start over next season with a good soil-less potting mix -see here - and a full range water soluble fertilizer like Foliage Pro. I think you will see significant improvement in both the health of your plants and the yield.

I am a novice gardener but I'll still throw in my two cents.

I just can't bring myself to discard used soil. I do get that "fresh" soil is best for plants like tomatoes and cucumbers and understand not reusing soil for tomatoes, cucumbers, strawberries and certain other plants but I would consider re-using the soil next year and blending it with manure for other hardier plants like flowers and herbs.

This year I did not do anything with my leftover soil until I was ready to plant. My leftover soil was from a few containers from two years ago. Based on research I did I put boiling water on the soil and then added manure to the soil at a 3:1 soil to manure ratio, i.e., for every 3 scoops of used container soil, I added one scoop of manure. I did not have a great growing season but I strongly doubt if it was related to the soil choices, things that were planted in new soil did not grow and things that were planted in repurposed soil did.

I will share my game plan for the upcoming year as I planned to create a post about it to get feedback but maybe I can get feedback here. At the end of the season, I am in zone 7 so it will probably be late October/November, I am going to pull up my non-perennial plants and will likely do the boiling water thing again. Hopefully by then I will have acquired a big receptacle and will dump my unused soil in that and then during the colder months basically use the receptacle as a compost bin and add food scraps, leaves, grass clippings, newspaper, coffee grinds, saw dust (if I can get some), comfrey (if I get a chance to plant) to the pile. I'll definitely be mindful of making sure that I am adding the right balance of greens and browns but won't be fanatical about it unless it presents a problem like there's a smell, but at some point, during the coldest months, probably January or February, I plan to carve out a couple of weeks where I will give it my full attention and do hot composting. The next phase of my scheme is that once things start to warm up a bit (early March), I may either buy some worms or capture some worms and add those to the compost bin, add more food scraps newspaper and let them do their thing.

And then when the planting season comes around I will use that soil for my plants, note that soil will likey be amended further to add other nutrients and moisture control. After all that I am still wary of planting tomatoes in repurposed soil and as of now I will likely buy the soil for tomatoes and cucumbers, but it really depends on how much planting of those particular plants I plan to do next year. If I only do a few containers of tomatoes and cucumbers I will likely buy the soil, but if I go hogwild, and it appears like my repurposed soil is the good stuff, I may plant some of the hardier tomatoes and cucumbers in the repurposed soil.

Also, I'm not sure if extension offices analyze container soil, but if they do I may stop by my local extension office and discuss what I'm planting and how I'm planting it with one of the master gardeners.

Annie, if you do further research you will find that highly organic materials - composts, manures, worm castings, etc. - make very poor additions to any container planting situation. They just do not hold up well and tend to be excessively moisture retentive. This results in a breakdown of the material over time and a loss of drainage and porosity.

Container soils are not usually subjected to traditional soil testing as they contain no soil per se but a collection of very durable organics (bark fines, peat) and mineral particles. And because there is no real soil, there are few nutrients present, so nothing really to test for!! All nutrients are supplied by the gardener/grower, not by the soil :-)

I'll direct you to the same link I directed Patches that explains simply but in great detail precisely HOW container soils work and ways to go about creating the soils that will best match your container gardening needs. Big hint: none of them contain composts or manures :-)) Read this!!!