To grow lavender from seed successfully, you will need to provide consistent warmth and light, with bottom heat initially, and then consistent lighting for 12 to 16 hours per day.
You will need good quality lavender seeds, seedling trays to plant into, good quality seed starting mix, shelving on which to place the containers, a heat mat, and lighting.
You can use any type of seedling tray that you wish to use. You can use seedling trays, paper pots, small pots, or even soil blocks to plant the seeds into.
Any good sterile seed starting mix will do. We add a small scoop of All Purpose Fertilizer to our tub of potting mix, and mix well before filling the trays with the soil.
Lavender requires full sun, and good drainage. It grows best in a sheltered area, and will benefit from some form of winter protection in colder climates, like covering with burlap or leaf mulch.