I've already started my first batch of seedlings! hooray! Right now i've successfully germinated about 3 types of lettuce. They are already about a week old and the tallest one is about 2cm. I put them in seedling trays with primarily cocopeat medium. I just water them right now... but won't i need to put any starter nutrients soon?

I have bought the following ingredients for use during the growing period:

* Peter's Hydrosol

* Calcium Nitrate

* Magnesium Sulfate

* Ferrous Sulfate

Unfortunately there was no mention of what the nutrient formula is for seedlings from 1 to 3 weeks old before i transplant them. I'd appreciate if someone could share their formula for seedlings applicable to lettuce. Tnx a lot!