I started my Collards, Kale, Eggplants, and Kohlrabi indoors about a month before planting time. I have a setup with a light and a thermostatically controlled heat mat. The plants sit in a tray for easy watering from the bottom. I bought everything on Amazon.
This setup is working pretty well. But it would be nicer to have a light that was wider because this single bulb one only case a narrow beam.
I live in Zone 9 so our growing season is opposite from most of the country. These plants are for what we call the second Warm Season which is about late August till late November.