The fertilizing I can't provide any input on, but the temperatures- I keep my guys 78-85 degrees constantly. Less and they seem to grow a little more slowly.

At nights temps can linger around 75-80, but not much less unless it's really cold outside (sub 40 deg.)

For seed starting, I usually use the ProMix with no fertilizer added. After they have sprouted I use an orchid fertilizer diluted to half strength. I started that just because I had the orchid fert and found that it worked for me.

As ab mentioned above, higher temps are better for the seedlings. The problem for me is that my light rack is in the basement which has an ambient temp of about 55 F. I compensate by using heating pads under the trays, but, at best my soil temp doesn't get above 65F. The result - I get good healthy seedlings, but they just take longer to germinate and mature.
John A

Thanks folks for your input! I'm starting seeds in my heated shop with an ambient temp around 60F, so I guess I need to isolate them in a prop chamber with a light.......

If you can keep them in an area that has a little warmer temp just until they germinate, usually they will be alright with a lower temperature afterward. About anywhere literally works.. some folks start their seeds on top of their entertainment centers, near their computers, top of the fridge, etc etc. Just somewhere that stays slightly warmer.

I germinate in baggies at a temp around 83ðF, but then they go into a starter cell in a cold corner of the house, 60-65. No problems other than slow growing, but I wouldn't sow at that temp unless you have a couple months to wait.