Light curl on my leaves

[fireman949]

We are in 7a / North Mississippi

I started my seeds around January 15 this year. They sprouted almost immediately and now some are near 12" tall. After potting up to 4" round pots, I started feeding with a highly diluted fish emulsion water solution about once a week (aside from keeping them watered with no fert). I use 1 to 1.5 tsp Neptune Harvest 2-4-1 per 32oz water . This is the second year I started from seed and the first year I've had good looking plants. They've been sitting in an upstairs room kept between 56 and 72* depending on outside temps with a 4' 4 lamp shop light, Aqua/Plant tubes and a ceiling fan on low or medium depending on my mood.

I'm about a week from putting them out in the raised beds under a cold frame and wall o waters, but some of the leaves on the taller plants have a light curl and some of the very tips have a slightly yellowish tint seen here :

I think it is because the lower leaves are far from the light, but I've kept the light within about 1" or 2" of the top of the plants - they are just 12" tall now.

I put the 3 plants I want to get in first outside in the open garage to get about an hour of sun, but it was in the lower 50s inside the garage so they came back in quickly.

I don't think I'm over feeding (I could be, never used fish emulsion before), but I'm wondering what is causing the curl and yellow.

I wait to water until the soil is not damp and the pots are lighter weight - am I waiting too long between waterings?