I made a new video on how to start seeds indoors to reflect all I've learned lately. This included making cool paper pots and cardboard tubes.
To start seeds indoors
You need warmth and light and water. Lots of light and warmth, and not much water. Soaking wet seeds or seedlings will die off, imagine having your feet in water all the time, not fun.
I start my seedlings near the furnace in our basement. You can also buy a waterproof grow mat that is like a heating pad but built for seeds starting. Don't go and use your heating pad for this, OK?
When the seeds start to sprout, its time to move them under the grow lights. The seedlings do not have to be as warm once they are started. But is is very important to keep the seedlings directly under the lights, basically touching the bulbs. With our DIY grow light rig, you can slowly raise the grow light as the plants grow.
I have found putting seed trays in the window doesn't work. The plants get very leggy and top heavy. When you transplant them, they fall over in the wind. Your experience may be different, as I live in New England, where the winter light is poor at best.
For the grow light, we use regular fluorescent bulbs, not the expensive lights. For seed starting, this works fine.
You don't want to over-water your seedlings. This can cause mold and fungus to grow and will kill the young plants. Best is slightly moist to slightly dry. Many of the seed starting trays have a wicking mat under the seed pots, and this works pretty good. Watering from underneath instead of over the plants is best. I do not mist the plants.
I use a prepared seed starting mix, I don't make my own, too much work, I think. Do not use regular potting soil or soil from your garden. You can get Clyde's Planner here.