The nights are just beginning to stay in the upper 30's, but I am still not brave enough to set plants outside just yet. Our average last frost date is May 20th and my front yard micro-climate can be 5-10 degrees colder than surrounding locations on a clear night. I have yet to connect my electric space heater or my propane heater out in the greenhouse. And my home weather station was still showing low nighttime temperatures below freezing just last week. My indoor seedling racks are just about bursting at the seams, so moving out to the greenhouse will need to happen pretty soon.
I believe the #1 cause for spindly weak seedlings is not enough light. I use 6 - T12 or 4 - T8 or 4 - T5 bulbs per shelf and my lights are on for 16 hrs each day. You might notice the placement of my TomatoCam in the photo. This is my new netcam that will be moving out to the greenhouse along with my plants soon. Come back as often as you like to monitor my growing season, here in Wasilla.