What Are Perennial Herbs
The term “perennial” refers to plants that come back year after year so with perennial herbs you can expect them to keep growing back every year after they have been planted.
Although perennial plants include plants such as trees, shrubs and woody plants, they include herbaceous plants and herbs that you might not expect to survive a winter.
Herbs That Come Back Every Year
Lavender, rosemary and sage are present all through the year and are some good examples of woody herbs that are like shrubs. These herbs are perennial and can survive throughout the winter keeping their leaves.
Other perennial herbs such as tarragon, chives and mint are less hardy so may die back as the temperatures drop over winter.
Dying back during the winter doesn’t mean the herb is not still growing as the root system is still alive underground. When the weather warms in spring the plant sprouts into growth and new shoots and leaves emerge.
Differences With Annual Herbs
Annual herbs complete a whole life-cycle in one year. They are typically soft-stemmed plants and cannot withstand cold temperatures over winter.
They grow leaves, flowers and go to seed in the same year.
Annual herbs will need to be grown from seed each year and have a limited harvest before the season finishes and the plant dies.
Along with annual and perennial herbs, there are biennial herbs which most notably include parsley, angelica and caraway.
Biennial herbs take two years to complete a life cycle. In their first year biennials like parsley produce leaves which can, of course, be harvested when needed. In the second year, they produce flowers and then go to seed and die back. Biennial herbs will need to be seeded in rotation every year.
Herbs That Will Survive Over Winter
Perennial herbs that can survive over winter fall into a few groups. There are evergreen herbs that have leaves throughout the year. These tend to be the more woody herbs you use and the plants that resemble shrubs.
The great thing about evergreen shrubs is that you can use them throughout the year as the leaves are there to be picked. You will want to limit the amount you harvest during the winter of course.
Depending on the climate, evergreen herbs include:
Other herbs that will survive over winter will typically die back over winter. They are still perennial as the root system will survive underground and produce new shoots in the spring.
Perennial Herb Care & Maintenance
Perennial herbs are great because they are most often, the easiest herbs to care for. Hardy perennial herbs can take a fair amount of neglect and keep on growing.
The maintenance you will need to apply are things like:
Putting in supports for tall plants or herbs liable to be blown over. Stakes, pea sticks and wire loops can be put in early to prevent any plants like fennel from falling over in bad weather.
Cutting back herbs after flowering will encourage fresh new shoots and growth. It will also help to keep a nice shape to the plant and prevent it from becoming straggly.
During very dry spells ensuring your herbs are watered enough will be necessary. This is going to be especially important if you grow herbs in containers.
When To Cut Back Perennial Herbs
Perennial herbs that die back over winter and be cut back after the growth dies back at the end of autumn if there is a chance at self-seeding. Alternatively, the dead growth can be left until late winter to early spring before being cut.
It is also a good idea to cut back stems after flowering to prevent the plant self-seeding and to prevent the plant from getting too leggy.
Some herbs which are great for culinary or medicinal use can spread far too quickly in the garden.
Mint and lemon verbena are examples of herbs that can quickly outcompete and overrun a whole border if left unchecked. The best way to combat this is to plants herbs like mint in containers.
A container can be a pot on the patio or even buried in a border so you can still enjoy the herb in a border with other plants without the worry it is going to take over the whole bed.
Perennial Herb List
- Lemon Balm
- Winter Savory