There are thousands of herbs all belonging to separate plant families and needing different growing conditions. The lifecycle of herbs tend to fall into four main groups:
These grow from seed in the spring, the flower produces seeds and then the plant dies (borage is an example of this).
Biennials rapidly grow from a seed in the first year and their flowers produce seeds and later die in their second year (an example is parsley).
These perennial plants live for more than two years and die down each autumn to sprout again in spring (for example, mint).
Evergreen perennials live from year to year and keep green throughout the winter (an example of this is bay).
Within these groups are herbs of different hardiness. Tender herbs, like lemongrass, shouldn’t be exposed to temperatures that fall below one degree centigrade. Half-hardy herbs like lemon verbena will survive down to temperatures of minus five degrees centigrade, and hardy herbs such as sage, will be content down to minus ten degrees centigrade. There are even several very hardy herbs such as fennel, which will survive in temperatures much lower than that.