I am trying to determine a fertilization schedule for some tomatoes in 17 gallon containers next season.

I am thinking that for a non-SWC, unused ferts would just wash out the container's drainage hole, and be lost to the plant. Therefore, you would need to fertilize more often.

For a SWC, unused ferts would wash into the reservoir, and (assuming the reservoir does not overflow during the growing season) the fert would get carried back up into the soil and be made available again. So, you would not have to fertilize a SWC as often or as much as a non-SWC.

I am wondering if I am missing something, so would be glad to hear a more experienced opinion. Thanks.