Soil: Actually, this should be planting medium, but we just call it soil, even though there's no soil in the mix. Ok...to clarify that jumble of late night babble: Buy potting mix. Not potting soil. Potting soil is just plain dirt, and, though you can start seeds in it, your germination rates will be much lower. You can buy the specialty seed starting mix, but if you are starting a lot of seeds, it can get expensive. I find the standard potting mix works just as well. Miracle Grow is good, or one of the generic versions; just make sure it contains a wetting agent, or you'll be watering all. the. time.
There are recipes for your own potting mix, and I do mix my own, but not for seed starting. I get better results with the commercial mix.
Sprinkle the planting medium into your container. I always overfill mine.
Let your soil drain a bit before you start planting; nothing worse than seeds that keep floating to the top.
I use a popsicle stick for planting. I use them to mark my plants, so it's just what I have handy. You can use whatever works for you: sticks, pens, a skinny sibling...
The popsicle sticks? I buy them by the hundreds in the craft section of my local department store. They call them "craft sticks" since they never held popsicle, fudgesicle, or anything delicious, for that matter.
Gently press the soil side to side to get a hole in the soil. Or just pop some out, if you prefer. I put the stick in and wiggle it and voila! a hole! I generally go about half an inch deep.
It's hard to tell from the pic, but there's a line of holes, just in the first row. It's best to go one row at a time so you don't miss any cells.
Today I'm planting tomato seeds. Tiny, huh?
Drop the seed into the hole, and you are done! There's no need to cover the seed. As you water, the soil will fall back into the hole. I've seen some instructions that say to pat the soil in over the seed. Not a great idea, from what I've learned. At work, we don't even dig a hole for seeding. We put the seeds in and cover them with course vermiculite, which is very lightweight and lets the seedling pop out easily.
If you are planting more than one variety of seed per flat, you definitely want to label each variety as you plant them. Here's where all those tasty fudgesicles pay off. Oh, wait...I mean, here is where you'll use those nice, fresh craft sticks. Yes, that's what I meant. ;)
I put the variety on one side and the date started on the other.
Watering: I use an empty, clean dish detergent bottle for watering. This way I have more control over the amount of water, as well as where it goes. I still end up with some in the floor, but when you have 26 flats, it's just too much trouble to drag them to the sink, one by one.
Water daily. With good drainage, you should be able to give the seeds a good soaking once a day but not drown them. If you need to water more than once a day, go ahead. Just don't let your seeds and seedlings dry out.