Is Thyme A Perennial Or Annual?

Written by Becky Mathews
Published: September 23, 2022
Image Credit iStock.com/wmaster890
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Thyme is a popular herb and the holidays wouldn’t be the same without its festive aroma. If you want to grow some of your own, it couldn’t be easier. Thyme is a drought-tolerant herb that loves hot sun, but let’s start off with a simple question: is thyme a perennial or annual?

Thyme: Perennial or Annual?

Culinary thyme is a perennial not an annual. It’s an evergreen shrub that retains its foliage year-round but grows and flowers every summer.

The majority of thyme cultivars are perennials too, but culinary thyme is the hardiest. In the coldest areas, thyme can be grown as an annual.

The Difference Between Perennial and Annual

The difference between annual and perennial plants is simple. Annual plants only live for one year. Generally, they germinate in spring and die as winter approaches, packing their lifecycle into less than 12 months. On the other hand, perennials live for at least three years. Some perennials like thyme are evergreen, but others like lantana are deciduous and die back for winter.

It’s worth mentioning the biennials here. Biennials are often mistaken for plants that flower twice a year. Bi means two so it’s a good guess, however biennial actually means the plant lives for two years. They germinate in year one then flower, set seed, and die in year two.

Can Thyme Survive Winter?

Yes, thyme survives winter if it has very well-drained roots. It’s a Mediterranean sun-loving herb, but it’s hardy enough to tolerate frost if its feet are dry. To achieve this, thyme should be planted in gritty soil that drains quickly.

winter
Being a Mediterranean herb, Thyme can survive winter, but it’s not the hardiest herb out there.

iStock.com/mscornelius

USDA Growing Zone for Thyme

Culinary thyme grows in USDA growing zone 4 and above, but remember to keep it’s roots well drained. Thyme will rot in the hottest zones if it has consistently wet roots.

Is Thyme A Herb?

Yes, thyme is a herb and a very popular one because there are over 300 varieties. Thyme is in the thymus genus and it’s a member of the Lamiaceae family of mints. It’s an evergreen perennial herb related to oregano and it has a rich history alongside humans, more on that later!

The variety of thyme used for cooking is culinary thyme. It’s sometimes called English thyme and its botanical name is thymus vulgaris. It’s a bushy shrub with dark green tiny leaves that forms a short mat reaching about 10-12 inches in height and spread.

Culinary thyme is the original native plant, but the cultivars are also excellent plants for a kitchen garden. Cultivars have been bred in different scents and tastes such as lemon thyme and pretty yellow-green foliaged versions to suit everyone’s taste.

A Brief History Of Thyme

Thyme is native to the Mediterranean area where it’s cultivated and grows wild in the mountains.

It was used by the ancient Egyptians for embalming mummies and the Greeks burned it in their temples to honor the gods. In ancient Greek times, thyme inspired courage on the battlefield. This tradition lasted into the European Middle Ages when ladies of the court would give knights bouquets of thyme to promote bravery.

Experts think the Romans brought thyme to Britain when they invaded in 43AD and then settlers took it when they colonised the Americas and Australia.

Today, culinary thyme is researched for its anti-microbial activity. This article in the Journal of Medicine and Life investigates thyme oil’s potential antiseptic properties.

How Do You Pronounce Thyme?

Thyme is pronounced time. It’s derived from the ancient Greek word thuein which means burn or sacrifice. It describes the Greeks’ habit of burning thyme in temples.

Do You Let Thyme Flower?

You certainly can let thyme flower because they can be used as edible garnish and pollinators love them.

Culinary thyme flowers are tiny pink stars that sit just above the mat of foliage, but there are thyme cultivars with different colored blooms such as the white flowering Thymus serpyllum ‘Albus’ and Broad Leaf Thyme with purple flowers.

Should Thyme Be Cut Back?

Yes, cut thyme back after it’s flowered otherwise it can get leggy and produce less tasty foliage the following year.

It’s easy to clip back. Just use garden shears to snip off all the new season’s growth. Don’t throw away the clippings though, they can be hung up in a cool, dry place to dry out and be used over winter in soups, stews, and holiday stuffing. Spread any short pieces out on kitchen paper and once it’s dried pop it in a glass jar.

It’s worth mentioning that thyme rarely needs any fertilizer. It prefers poor, dry soil and if it’s fed, it’ll shoot upwards with barely foliaged woody branches that are unattractive and not much use in the kitchen.

How To Over-Winter Thyme

Thyme grows in zones 4 and above, but as we’ve already seen, it needs well-drained soil to survive. You may also find thyme cultivars are a little less hardy. Check the label for a growing zone before you plant it out.

As winter approaches, clip thyme back to increase air flow through its branches and ward off fungal disease. If you’re growing thyme in the ground, make sure it’s well drained. Dig them up and add grit to the soil if not, or move thyme plants into a container of gritty compost for winter.

In growing zones 3 and under, thyme won’t survive the long stretch of cold and wet – it is a Mediterranean native after all! Dig up plants and pop them on a bright windowsill for winter. They can go back outside when the frosts have passed.

Is Thyme Toxic To Pets?

Thyme isn’t toxic to dogs, cats, and horses, but it’s never a good idea to let pets chew garden plants. Thyme has lots of health benefits for humans and animals so it can actually enhance health. There are lots of pet supplements with safe amounts of thyme if you want to try.

Dog and cat head shot on white background
Thyme isn’t toxic to dogs or cats but it’s probably not a good idea to let them eat it.

iStock.com/adogslifephoto

Thyme Is A Perennial In Zone 4

In the majority of gardens, thyme is perennial, not annual and it’s easy to grow.

Thyme is an excellent addition to kitchen gardens and it makes a pretty evergreen divider too. Not only do bees love its flowers, but it’s also drought tolerant and full of essential oils that benefit our health. It’s always a good time to plant thyme.

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About the Author

I’ve been a professional writer since 2014 with special interests in the environment, particularly endangered animal and plant species. I graduated from the University of Reading, UK with an MA in history and hold University of Oxford qualifications in archaeology. Outside of work, I rehabilitate wildlife, work in my allotment garden, and play the piano badly.

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Sources
  1. , Available here: https://www.rhs.org.uk/plants/18213/thymus-vulgaris/details
  2. , Available here: https://www.aspca.org/pet-care/animal-poison-control/toxic-and-non-toxic-plants/thyme
  3. (1970)