Lettuce fertilizer?

[Elizabeth C]

I’ve read that fish emulsion is the best organic lettuce fertilizer; is there any kind of diy fertilizer I could use that I don’t have to buy? Like coffee grounds, or banana peel water, or something? The fish emulsion has NPK of 4-1-1, so is there something that could copy that I can make at home?
Also, when should I start fertilizing? My lettuce is still pretty small; has 2 or 3 sets of leaves.

 

[YumYum]

Lettuce likes nitrogen. I start just as soon or even slightly before I see the true leaves.

 

[Elizabeth C]

Thanks!