Just wanted to say that
giving seedlings nutes doesn't burn them when you do it right....I have done it every time my seedlings showed yellowing at the edges and have NEVER burned them. Yellowing means deficiency! Any nute guide will tell you that. There are actually many nute feeding charts that instruct you to give low strength nutes as soon as the first leaves appear. I'm not try to be negative or a Know-it-all or anything like that! But I was scared to give nutes to my plants because everyone said it was a big no no...and my girls grew very very slowly. I finally caved in and gave them a very low strength diluted mix, and they finally took off how they were supposed to.
You're not supposed to give nutes if your medium already has them, but if it is devoid of nutes, the baby has to get food from somewhere 
.
Here is
PROOF that giving a seedling nutes is pretty much necessary for many plants when your medium doesn't have any...
This is my blueberry starting out:
This is a few days later.....usually my seedlings are much bigger in just a few days, the 1st leaves get really long and start to take up the pot, but the blueberry (left) is still the same size. On the right, the skunk has yellow baby leaves and is stunted like the blueberry.
This is a week later....the skunk is working on it's second set of leaves and is still very small:
The Blueberry too is growing....VERY slowly, and the yellowing slowly working it's way throughout the plant:
This is the blueberry at day 15:
Horrible growth! Let me show you what one of my healthy plants looks like (
that I ferted from day 2) at day 14:
I finally caved in and gave the Blueberry nutes after everyone told me not to, and this is 4 days later:
Just wanted to show you that's
it's not always true that you should not fert seedlings! If you don't have N in your medium, then your babies have nothing to feed them...some girls come out hungry. Low strength nutes (especially organic nutes) will not burn them! No offense to anyone...but I'm not just repeating information I heard, as you can see, I have found out for myself! I now fert every seedling after a couple days and I have 11 healthy plants with
NO signs of burning.