Looks like an ok plant to me. Different varieties have different characteristics and tendencies to curl. Tomato leaves are very cool. I haven't read this elsewhere but I think the tomato plant uses them as tendrils by just observing my own masses of leaves. Back to yours. There are many reasons a tomato plant can curl that have to do with environment, toxins and simply poor general fertilization rather than a single obvious deficiency. IMO, this picture does not contain enough enough info to really rule in or rule out many of them. I would be sure to not over water the plant and smother the oxygen loving roots, though, so that is my suggestion, though just general. Is that a 240 mL cup? It might be very small and each time you water it , iof there is no drainage as the plant reaches transplant size, is a big change of soil water, especially if it collects on the bottom. This can interfere with nutrient take up as well.. Good luck.

Dan, I've used a few different mixes in containers and I like the sound of your sea soil. The problem with containers is that the system is really too small to set up a true organic soil system in them. People do all sorts of things and may technically get away with it, but I my abilities can't do a completely organic soil and get reliable production, since any "help" and you kid yourself that it is "almost organic". That said, I had some luck with a mixture of 1/3 compost (Black Kow Composted Organic), 1/3 peat & 1/3 perlite in summer but you must watch it doesn't get waterlogged. I know it sounds strange, but raw perlite is "organic". You could put some of those fancy rock dusts in there and dolomitic lime and give it a whirl. Problem is at some point your plants will need the nutrient boost of something like Miracle Gro, which is not organic, but not as bad as some make it out to be, either! There are some Fox Farms hydroponic/organic and Dutch Master hydro organic ones, but these things are really cost intensive and there is no way I could afford to even evaluate them. Tomato-Tone is organic and you can use some of it (the affordable option I would use) but a lot of experimentation is necessary to get it right in a bucket. Those are the tools I would use. There are others that are more expert than I am in this forum on organic methods in a container, but the problem is that ingredients and climates can vary enough that a lot of experimentation is necessary anyway and it is a bit much to ask of a container considering the nutrient demands of a big tomato plant. And a bigger contaner ( say, 25 gallons) can be costly to fill with organic nutrients only. There are other much more economic ways to go if you drop the requirement of deriving all nutrition from "organic" sources, for example pine mulch, etc, is cheap but offers no nutrition so it doesn't get you anywhere nutrient wise, though it might help you save on perlite. I can't answer whether your tap is appropriate for your plant, even knowing the pH is 7.5. That's because it will be the interaction among the tap, soil ingredients and amendments that determine the pH of the container. For example, if your soil starts on the acid side which it likely will it needs to be neutralized with some lime, but you can do what I do ... put less in and water with alkaline water for a while. Clearly that is not an optimal situation but to be honest my plants do fine despite all the issues with pH, and my tap is pH 7.7. But this is a fragil relationship and the only way to now for sure is to pH test your soil while you grow toget the hang of what's happening, if you are really enthusiastic. Just because it works for me, btw, doesn't mean it will work for everyone. We get lots of rain here and that frequently washes trhough soil mixesand I purposely open the tops wide to encourage that. No residue builds up from the tap or any of my not-organic supplements due to the rain. The common wisdom of hydroponics of a vegetative and a reproductive period fertilization schemes doesn't seem very pronounced to me when growing the tomato for the long haul. To be perfectly honest, I think all these mantras about vegetative stages and drastic changes during flowering stages are geared towards high value crops LOL. Really with tomato plants you want to keep the nitrogen at a baseline, low in all of my scenarios. You are not growing vines, they get quickly unmanageable for indeterminates and make few tomatoes, and most everyone here seems to agree that being pretty stingy with nitrogen is the way to go. That's the opposite of what you've done. When I grow my tomatoes, my seedlings have only 1/2 to 2/3 the nitrogen the producing plants do, so my nitrogen rate actually increases for me. At the end I back off though because the plants get less productive and unmanageable so there's a lot of give and take. Hope that helps a little, because nothing is as easy as it seems, so most people find something that works and get pretty stuck to it. Cheers PC

Likely if you eat tomatoes from the store they are production tomatoes. 1. They won't have the taste like a good gardener hybrid or heirloom tomato (in other word they tastes like cardboard). 2. They are hybrid, when you replant a seed from a hybrid plant, it won't be exactly like the original plant, it will have different characteristic and may not taste as good or have desired traits. I would rather order some seeds online and grow some dwarf tomato instead. If you intend to grow indoor you will need some good lighting and space. Something like this is minimum I would recommend for full size tomato indoor: https://www.1000bulbs.com/product/8256/FC105-S50OD.htm. So as you can see, tomato need lots of light which isn't not going to work in a single room dorm. Not only that, they need lots of soil, at least a 5 gallon container. So it's better off growing something like lettuce or basil indoor, or look for a dwarf or microdwarf tomato variety. Some variety to consider are: Red Robin, Tiny Tim, Silvery Fire Tree. For indoor potting soil, make sure you ask question and find the right potting soil that does not smell and perhaps pasteurized for indoor use, otherwise it will be an unpleasant experience. I don't buy potting soil, but I know "FoxFarm's Potting Soil" have good reputation so you may want to check them out, but I don't know how it'll smell. In my bedrooom I have an "AeroGarden Extra LED" that let me grow vegetable hydroponically, and it's LED light is bright enough to provide light for some extra plants in smaller container next to it. It is full spectrum and would be adequate for small dwarf tomatoes. It have a timer and shuts off after 12-16 hours. It is also very easy to make your own affordable indoor hydroponic setup. However, considering you live in a dorm, I don't know if you may have issues with campus authority who will be concerned with cannabis growing which is quite popular with hydroponic growing (not that I'm trying to give an idea).

The "primary" nutrients all plants need to varying degrees are nitrogen, phosphorous, and potassium. Without those nutrients supplied in some form anything else makes little to no difference. Neither peat nor coir supply any of those nutrients. Most brands of fish emulsion supplies all 3 in small amounts. That is why plants normally get transplanted to a growing medium of some sort that contains those nutrients. " though the plugs are bigger ones and lasted for a good 6 weeks last year. Seedlings are just over 4 weeks old at this point." Yeah I know the size of the plug flats you are using. We use many of them in the nursery but for germination and growth only to the first true leaf stage. Then they get transplanted so that feeder root development can begin and you begin to supply them with a diluted form of nutrients. Dave