Thymus citriodorus (Lemon Thyme)

Thymus citriodorus, commonly called Lemon Thyme or Citrus Thyme, is an aromatic evergreen shrub with a compact cushion form which can gradually spread into an undulating ground cover. It has small yellow-green leaves, which can have variegated margins in some cultivars, and spikes of tiny pale-pink flowers.

It is a drought-tolerant shrub native to the Mediterranean basin.


Quick Overview

TYPE

Type Shrub

HEIGHT&WIDTH

Thymus citriodorus height and width

BLOOM TIME

Thymus citriodorus bloom time

SUNLIGHT

full sun

HARDINESS

hardiness (-12ºC / 10º F)

DROUGHT TOLERANCE

drought tolerance aprox 3 months

ORIGIN

origin mediterranean basin

Lemon Thyme scientific name

  • Botanical name:  Thymus citriodorus (TY-muss sit-ree-oh-DOR-us)
  • Family: Lamiaceae (lay-mee-AY-see-ee)
  • Common name: Lemon Thyme, Citrus Thyme
  • Other names: Thymus x citriodurus.  For many years it was thought to be a hybrid between T.pulegioides and T. vulgaris , but recent DNA analysis has revealed that it is an independent species and is now known as Thymus citriodorus.
NameMeaning
ThymusThere are several versions of the origin of the name:
1- From the Greek word thymon meaning smoke or to fumigate. Related to its use as an incense for its fragrance.
2- From the Greek word thumos meaning courage. Thyme symbolised bravery.
3- From the Greek word thymos, meaning perfume. Because of its intense fragrance
citriodoruscitrus scented (citri = citrus, odorus = odour,smell)

How to identify Thymus citriodorus

Thymus citriodorus shrub (Lemon Thyme, citrus thyme)

Shrub

Compact, aromatic, evergreen woody shrub with upright to decumbent stems forming a cushion shape. It will gradually spread into an undulating ground cover as it layers its stems on the ground forming new roots.

It has small yellow-green leaves, which can have white or yellow variegated margins in some cultivars, and clusters of tiny pale-pink flowers.

The shrub has an average height of 20 cm (0.6 ft) and a width of around 30 cm (1 ft).

Thymus citriodorus stem (Lemon Thyme, citrus thyme)

Stem

The stems are upright in the middle and decumbent on the edges. They are reddish and covered with short hair.

Like other thymes, the young stems are squared but become rounder and woody at the base as they age.

They have opposite leaves at each node and tufts of smaller foliage in the leaf axils. 

Spikes of tiny flowers appear along the terminal part of the stem.

The stems will naturally form roots as they touch the ground, leading to the shrub’s horizontal spreading.

Thymus citriodorus leaf (Lemon Thyme, citrus thyme)

Leaf

The leaf has an intense citrus aroma with dark green to yellow-green colour

Some cultivars will have white or yellow variegated margins.

The shape is elliptical with a rounded tip, flat margin and a prominent central vein.

Thymus citriodorus flower (Lemon Thyme, citrus thyme)

Flower

The inflorescence has a globose or spike form and is composed of tiny flowers in whorls around the stem.

The flowers are pale pink with a fused corolla. They are two-lipped, the upper lip has 2 lobes almost fused into one, and the lower lip has 3 lobes.

Clusters of pale-pink flowers appear during the summer.

Thymus citriodorus usage

Ornamental

The Lemon Thyme forms a pretty cushion of yellow-green or variegated foliage and pale-pink flowers with a lovely lemon aroma, which is a very interesting addition to your garden.

It looks great in rock and gravel gardens, especially in aromatic or herb gardens, due to its intense lemon aroma.

It can be used as a solitary plant or planted in groups. It can be planted in containers, beds or borders. It is also a good choice for a ground cover due to its spreading growth.

It’s ideal for drought-tolerant and low-maintenance gardens.

Medicinal

Lemon Thyme leaves and essential oils have interesting applications in the medical industry.

Studies have demonstrated its antioxidant activity and also, its antimicrobial and anti-inflammatory properties in treating skin acne.

Cosmetics

The strong lemon fragrance and its antiseptic and deodorant properties make Lemon thyme essential oil very popular in perfumes, deodorants, soaps and skincare products.

Culinary

Lemon Thyme is a versatile herb in any cuisine, especially in the Mediterranean one.

This plant gives a typical thyme flavour mixed with a lemon zest essence

It has many gastronomical uses in any recipe requiring a citrus flavour: salads, teas, jams, desserts, and cooked dishes such as soups, stews, and roasted and grilled meat or fish.

Other uses

The dried leaves can be used to produce scented sachets for cupboards and drawers to scent clothes and linen and repel cloth moths.

Lemon thyme is used as a homemade insect repellent. Crushing the leaves and rubbing them on your skin will repel annoying insects such as mosquitos.

Studies have demonstrated the potential of Lemon thyme to manage pests in agriculture.

Biodiversity

The flowers of Lemon thyme are rich in nectar, being very attractive to bees, butterflies and other pollinating insects. Other insects, such as ladybugs, hoverflies, and parasitic wasps, will also gravitate to this plant. These insects, in turn, attract various birds. All this wildlife enhances your garden’s biodiversity.

Cultural

Thyme symbolises love and courage. The knight´s cloaks and tunics would have thyme leaves embroidered by their loved ones.

Greeks believed that thyme would bring courage and motivation and used thyme sprigs in baths and the clothes of knights before battles.

How to care for Thymus citriodorus

Cold exposure

This thyme is quite hardy. It is frost tolerant and can endure temperatures down to -12ºc (10ºF). However, it will need winter protection until it is fully established. Add some mulch to protect the roots from low temperatures and the foliage from the wet soil.

Sun exposure

Needs full sun, at least 6 hours per day. It can tolerate some shade but at the expense of less aroma and foliage.

Soil

It likes poor, well-drained stony soils. Sandy and loamy soils are ideal. It tends to rot on wet soils.

It prefers neutral and mildly alkaline soils but can also tolerate slightly acidic soils.

Watering

Thymus citriodorus is a drought-tolerant plant native to the Mediterranean basin and adapted to hot, dry summers. So it rarely needs watering once established. It can go for about 3 months without water if the temperature is not excessively high.

During the first two years after planting, you must water the young thyme every two to three weeks during the summer.  Allow the soil to dry out between watering. In case of a heat wave, water more frequently. Monitor your plants closely and look out for any signs of stress.

To preserve the soil´s moisture, you should add mulch around the root area of the Thyme (but not too close to the base). Wood chips and gravel are good options for mulching. 

It especially dislikes humid winters and cannot tolerate being water-logged.

Other conditions

It can endure strong windy conditions but not sea exposure.

It is best to plant it during the Autumn so it will have all winter to develop its roots.

How to prune Thymus citriodorus

Like other thymes, this shrub needs to be pruned a couple of times during the year to remain vigorous and maintain its compactness.

Ideally, you should give it a prune in the spring to prevent it from becoming too woody and then another prune in late summer after flowering to encourage bushiness. Be careful to always prune above the leaf, as the stems will not regrow if it is cut back too hard.

Thyme should be harvested just before flowering when it has the highest quantity of essential oil. 

How to propagate Thymus citriodorus

This thyme can be propagated by seeds, cuttings, layering and division.

Propagation by seed

Sow in spring in a cold frame or in autumn in a greenhouse. Do not cover or barely cover the seeds as they need light to germinate. The seeds usually germinate in 2 to 4 weeks at around 15ºC (60ºF).

Plant the seeds in individual pots as soon as they are strong enough to handle. Keep them in the greenhouse or cold frame to grow a bit more. Plant them in their final location after the last frost in spring or in autumn.

When transplanting, pinch the tip of each stem to stimulate more branching to create a bushy form.

Propagation by cuttings

Thyme is easy to propagate from cuttings.

Semi-ripe cuttings can be taken from mid-summer to early autumn. Take a 5 to 8 cm (2.7 to 4 in) cutting with a heel or at a node from the current year’s growth. Roots will form within a few weeks. Semi-ripe cuttings can be placed in a cold frame over winter. 

Plant them out in late spring after the last expected frosts.
Basal cuttings of young shoots can be taken in the spring. Roots will form in a frame (to maintain moisture) during the summer, and the plant will be ready to plant in the final spot in autumn.

Propagation by layering

Lemon thyme is especially easy to propagate by layering. Like other ground-covering thymes, it has horizontal stems that root when in contact with the ground.

Bend the stem down, hold it to the ground with a peg or rock, and cover it with soil.

Propagation by division

After this plant has been established for a few years, it is ready to be propagated by division. It can be divided in spring or autumn. 

Dig up the plant and carefully divide into 2 or 3 smaller sections. Each section should have a robust root structure.

The divisions with larger roots can be planted directly in their final position in the garden. 

The smaller divisions with less developed roots will first need to be potted and grown in a cold frame or greenhouse until they are strong enough to be planted in the garden.

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