Culinary medicinals like cilantro and fennel are annuals/biennials, yet I’ve not had to plant them in years as they keep self-sowing and making their continual patch.
Depending on where you live on the globe, some herbs may be perennials to you but annuals to another. If you live in a temperate zone, I recommend choosing three-fourths perennials (or self-sowing annuals) to one-fourths annuals, so that your garden comes back year after year and you’re not always starting from scratch with your plantings. Culinary medicinals like cilantro and fennel are annuals/biennials, yet I’ve not had to plant them in years as they keep self-sowing and making their continual patch. Some other medicinal annuals that self-sow are anise hyssop ( Agastache foeniculum), holy basil, chamomile ( Matricaria chamomilla), and sweet Annie ( Artemisia annua).