The lower leaves of my miniature tomato variety are turning yellow unfortunately. I have been fertilizing them with a citrus fertilizer, thinking that would be OK. They receive enough light (12 hrs), so I'm afraid I have been overwatering them. Can they still be saved? I have watered them again after letting them dry out a bit till the leaves started to droop a little. What else can I do? Do have to plant new seeds?

Thanks!

Unfortunately there are many possible candidates for that conditions, ranging from the mundane (psyllid infestation) to the exotic (poor water quality).

However my gut feeling given the otherwise healthy look of it and the apparent lack of "sugar" (psyllid droppings) is this is simply a case of overwatering: remember tomatos don't like too much water and as the season gets cooler they need less and less of it.

Martwlk, where are you located? That is the most important information before giving any type of advise. Putting that information in your profile is very important. Good luck with your growing issues.

Actually, I have a miniature 'garden' inside, using a DIY grow light that closely matches sunlight, here in the Netherlands. Other plants like oleander, zucchini and basil are growing and blooming very well, so the environment isn't an issue

I'd trim off the tomato's yellowed leaves and water less. The plants look wonderful.
My aunt is from Amsterdam.