I haven't grown onions for a couple years, but I seem to remember some little curls on the tips and they turned out fine. Maybe they just like to curl.

Sue

Does anyone know why the tops where the seed heads were are getting burnt off?

the onion seedlings look great. what's wrong with them? they're a good color and standing straight up. my only question is why are you growing them under lights in late march in zone 8. they'll grow better outside now than indoors. I'd take those seedlings and plant them out asap. Same goes for everything you have planted except the peppers.

Because of how much rain we're getting and the fact that it sometimes gets to around 32 F and sometimes around 28 F. I don't have a cloche or floating row cover.

I agree with WOKNEY.32F is fine with onions. even 22F and lower than that, as long as you harden them up first.
I dont understand the rain issue ! If too little then water them, if a lot of rain, thats ok as long as your garden had adequate drainage. onion family over winter in my zone(7b, 8a)I never start them indoors. the only reason to do that would be to germinate the seeds early.

I might harden them starting tomorrow or so... and plant on Friday. If I planted outside, I'd put a heavy layer of some straw or whatever that I have around them to protect them.

If I put straw or hay, how high to the top of the plants can it be without killing them?

stuffradio: some of that looks like it is going leggy. hardening can i think be started anytime but get the lights closer for the remainder of the time indoors. 1" from the tops if possible, if they're fluorescent.

as for why folks on the west coast start indoors even when our spring temps are mild... high winds + heavy rain = dead seedlings.

I know not all zone 8's are created equal but I don't think you need much straw or hay. But if you insist I wouldn't want to cover more than about 1/3 to 1/2 their height. You should look up the recommended planting dates from your cooperative extension office, I bet you're fine. I overwintered some onions (but with a very cold Jan with lows in the single digits I lost about 2/3) and started some from seeds around Christmas. The ones that I kept in containers until early Mar were not as well off as the ones I put in the ground just weeks after germination in late Jan.