Thymus citriodorus (Lemon Thyme)

Thymus citriodorus – Lemon Thyme: A Complete Guide

Thymus citriodorus, commonly known as Lemon Thyme, is a compact, evergreen herb in the mint family (Lamiaceae). Once considered a hybrid, DNA analysis now recognizes it as a distinct species. Native to Europe, it is cherished for its citrus-scented foliage, culinary uses, and pollinator-friendly flowers. With a spreading, mounding habit and aromatic leaves, it brings ornamental and functional value to any garden.

Aside from Lemon Thyme, the Lamiaceae family includes other popular herbs such as rosemary, basil, mint, sage, and oregano.

Native Range

Lemon Thyme is believed to have originated in Southern Europe, although its exact native range is debated. It is widely cultivated across the Mediterranean and temperate regions for its ornamental beauty and culinary value.

Plant Type and Habit

Lemon Thyme is an evergreen sub-shrub with a mounding or spreading habit. It forms low clumps with fine-textured, aromatic foliage that gently spills over garden edges or fills in spaces between pavers.

Size

This herb typically grows 6 to 12 inches (15 to 30 cm) tall and spreads 12 to 18 inches (30 to 45 cm) wide. Certain cultivars may grow more compactly or have trailing habits.

Lifespan

Lemon Thyme is a perennial, providing fragrance and greenery for several years. With proper care, it remains productive and ornamental year-round in mild climates.

Flowers

Lemon Thyme produces tiny, tubular flowers in pink or pale lilac hues, appearing in whorls at the stem tips in early to mid summer. While subtle, they are highly attractive to bees and butterflies.

Fruits

After flowering, small brown schizocarps form, splitting into nutlets. These are rarely harvested, as most Lemon Thyme is propagated vegetatively.

Foliage

Leaves are tiny, ovate, and evergreen, usually bright green and strongly lemon-scented. Some cultivars feature variegation in silver or gold. The foliage is simple, with entire margins.

Hardiness

Lemon Thyme is hardy in USDA zones 5–9. It tolerates heat, drought, and moderate cold, though winter wetness should be avoided.

Uses

• Culinary: Adds a citrusy note to poultry, fish, marinades, vegetables, and dressings. Best used fresh or as a garnish.
• Ornamental: Attractive mounding habit and fragrant foliage enhance borders, patios, and rock gardens. Complements other sun-loving perennials.
• Aromatic: Used in potpourri, herb pillows, and natural air fresheners. Crushed leaves release a refreshing lemon scent.
• Medicinal: Traditionally used in teas or infusions to aid digestion, soothe coughs, and relieve mild respiratory symptoms.
• Pollinator Garden: A magnet for bees and butterflies during summer bloom. Supports biodiversity and pollination.
• Ground Cover: Suitable for dry slopes, stepping stones, rock crevices, and low-maintenance lawns. Helps suppress weeds. Colorful Creeping Thyme Varieties As Lawn Alternatives
• Container: Perfect for herb planters and mixed arrangements on sunny balconies or terraces. Offers easy access for cooking and decoration.
• Cottage Garden: Fits well into informal garden designs where herbs and flowers mix freely. Adds color, texture, and fragrance.
• Companion Planting: This aromatic herb repels plant pests, making it a valuable companion in vegetable gardens.
• Mosquito-Repellent: The strong essential oils in thyme help repel mosquitoes, making it useful around seating areas or patios.
• Bank & Slopes: An excellent erosion-control plant for sunny banks or dry embankments, providing coverage and resilience.
• Butterfly Garden: Contributes nectar and habitat to pollinator-focused gardens. Especially attractive to small butterflies and native bees.
• Drought Tolerant Garden: Thrives in xeriscapes and other low-water-use landscapes. Perfect for dry Mediterranean-style designs.
• Edible Garden: A flavorful and decorative addition to herb beds and edible landscapes. Pairs well with other culinary plants.
• Rock Garden: Natural fit for rocky, gravelly soils and alpine gardens. Foliage spills beautifully over edges and stones.
• Border: Makes a charming front-of-border plant, adding soft color, evergreen interest, and structure throughout the year.
• Mass Planting: When planted in groups, it forms an aromatic, attractive mat of foliage that brings cohesion and visual rhythm to planting schemes.

Wildlife Value

Lemon Thyme attracts pollinators such as bees and butterflies, making it a welcome addition to wildlife and pollinator gardens.

Drought Tolerance

Once established, it is drought-tolerant. It prefers dry, sandy, or rocky soil and thrives with minimal watering.

Deer and Rabbit Resistance

The intense lemony aroma and essential oils render it unappealing to deer and rabbits.

Toxicity

According to the ASPCA, thyme is non-toxic to pets. However, large quantities of thyme oil may cause irritation.

Invasiveness

Lemon Thyme is not invasive, though it can spread moderately in favorable conditions. Prune or divide regularly to manage size.

Benefits and Drawbacks of Lemon Thyme

Benefits

• Fragrant and Edible: Adds a delightful citrus aroma and taste to dishes, teas, and garden spaces.
• Drought-Tolerant and Hardy: Requires little water once established and thrives in hot, dry conditions.
• Low Maintenance: A resilient herb with minimal care needs and long-lasting beauty.
• Pollinator-Friendly: Supports beneficial insects and wildlife with its nectar-rich flowers.
• Deer and Rabbit Resistant: Naturally repels herbivores, making it ideal for rural and suburban gardens.
• Attractive Ground Cover: Forms neat, aromatic mats perfect for edging, paving, and rock gardens.

Drawbacks

• Root Rot Risk: Poor drainage or excessive watering can lead to fungal issues.
• Woody Growth Over Time: May become leggy or woody if not pruned regularly.
• Slow from Seed: Germination and growth are slow; most gardeners prefer cuttings or nursery plants.

How to Grow and Care for Lemon Thyme

Planting

• Location: Lemon thyme thrives in full sun. Choose a location with at least 6 hours of direct sunlight daily.
• Soil: Plant in loose, sandy, or rocky soil with excellent drainage. Lemon thyme prefers neutral to slightly alkaline pH. Avoid waterlogged or clay soils to prevent root rot.
• Spacing: Space plants 12 to 18 inches (30 to 45 cm) apart to allow airflow and room to spread.

Watering

• Frequency: Water sparingly. Allow the soil to dry out between waterings. Overwatering can lead to root rot.
• Young Plants: Keep soil lightly moist until established.
• Heat Tolerance: In extreme heat or drought, water occasionally with a deep soak to maintain vigor.

Fertilizing

• Minimal Feeding: Fertilization is rarely needed. Too much fertilizer can reduce aromatic oils and compact form.
• Optional: Apply compost or half-strength liquid fertilizer in early spring if soil is poor.

Pruning

• Timing: Prune after flowering to encourage bushy growth and prevent woodiness.
• Maintenance: Trim lightly throughout the season to shape and promote fresh leaves.

Overwintering

• In-ground plants: Mulch lightly in fall to protect roots in colder climates (zones 5–6).
• Containers: Bring indoors before frost or shelter in an unheated greenhouse.

How to Harvest Lemon Thyme

When to Harvest

• Best Time: Harvest just before flowering when the lemon scent and essential oils are at their peak.
• Morning Harvest: Pick in the morning after dew has dried for the best flavor and aroma.

How to Harvest

• Snip Tips: Use scissors to cut 4–6 inch stems above a leaf node. Avoid cutting woody parts.
• Leave Growth: Always leave a few inches of growth to allow the plant to recover and regrow.

Preserving

• Drying: Air-dry in small bundles or on screens. Store in airtight jars away from light and heat.
• Freezing: Freeze sprigs in oil or water using ice cube trays for long-term use.

How to Propagate Lemon Thyme

From Cuttings

• Take 4 to 6 inch cuttings from healthy, non-flowering stems in late spring or early summer.
• Remove the leaves from the bottom half of the cutting.
• Place the cutting in a well-draining medium such as moist sand, perlite, or a mix of potting soil and vermiculite.
• Keep the cuttings in a warm, bright location out of direct sunlight.
• Mist regularly to maintain humidity around the cuttings.
• Roots should develop in 2 to 3 weeks.
• Once rooted, transplant the new plants into individual pots or directly into the garden.

By Division

• Divide mature plants every few years in spring or early fall.
• Carefully dig up the entire plant.
• Separate it into smaller clumps, ensuring each has healthy roots attached.
• Replant the divisions immediately in well-drained soil.
• Water thoroughly to help them establish in their new location.

By Layering

• Select a low-growing, flexible stem in the garden.
• Bend it gently to the soil surface and make a small nick where it touches the ground.
• Cover the nicked section with soil, leaving the growing tip exposed.
• Keep the area slightly moist to encourage rooting.
• After a few weeks, roots should form at the buried section.
• Once rooted, cut the new plant from the parent and transplant it elsewhere.

By Seed

• Start seeds indoors 6 to 10 weeks before the last expected frost.
• Scatter seeds on the surface of moist seed-starting mix and press lightly.
• Do not cover seeds, as they require light to germinate.
• Cover the tray with a dome or plastic wrap to maintain humidity.
• Place the tray in a warm, bright area and keep the soil evenly moist.
• Germination typically occurs in 14 to 21 days.
• Once seedlings are large enough, transplant into pots or the garden after hardening off.

Common Pests and Diseases of Lemon Thyme

Pests

Aphids

• Symptoms: Leaves may curl or become distorted, and a sticky residue (honeydew) may be present.
• Treatment: Spray the plant with a strong stream of water or apply insecticidal soap or neem oil to affected areas.

Spider Mites

• Symptoms: Fine webbing and yellow-speckled leaves, particularly during dry weather.
• Treatment: Increase humidity around the plant and apply neem oil or insecticidal soap to control infestations.

Whiteflies

• Symptoms: Small white insects fly up when the plant is disturbed; yellowing and weakened foliage.
• Treatment: Place yellow sticky traps near the plant or spray with horticultural oil or insecticidal soap.

Mealybugs

• Symptoms: White cottony clusters appear on stems and leaf joints; leaves may become sticky or drop.
• Treatment: Dab insects with rubbing alcohol or treat the plant with insecticidal soap. Use systemic treatments for persistent infestations.

Scale insects

• Symptoms: Brown or white waxy bumps on stems and leaves, often accompanied by sticky residue and black sooty mold.
• Treatment: Remove manually or apply neem oil or horticultural oil to suffocate the pests.

Fungus gnats

• Symptoms: Tiny flying insects near soil surface; larvae may damage young roots, leading to stunted growth.
• Treatment: Allow soil to dry between waterings, use sticky traps, or apply beneficial nematodes to target larvae.

Weevils

• Symptoms: Irregular holes in leaves and root damage from larvae in the soil.
• Treatment: Handpick visible adults or introduce beneficial insects such as nematodes to target larvae in the soil.

Diseases

Powdery mildew

• Symptoms: White, powdery patches form on the leaves and stems, reducing plant vigor.
• Treatment: Prune affected parts, improve air circulation, and apply a fungicide formulated for powdery mildew.

Root Rot

• Symptoms: Wilting foliage, yellowing leaves, and mushy roots, typically caused by poor drainage or excessive watering.
• Treatment: Ensure excellent drainage, avoid waterlogged soil, and replant affected plants in fresh, dry soil if needed.

Alternaria

• Symptoms: Brown to black circular spots on leaves, often with concentric rings. Can lead to leaf drop if left untreated.
• Treatment: Remove infected leaves, improve airflow, and apply a general-purpose fungicide.

Rust

• Symptoms: Orange or rust-colored spots on the underside of leaves, which may spread quickly in humid weather.
• Treatment: Remove affected foliage and apply a rust-specific fungicide if necessary.

Botrytis (Gray Mold)

• Symptoms: Fuzzy gray mold appears on stems, flowers, or leaves, often in damp and overcrowded areas.
• Treatment: Increase spacing and air circulation, remove infected parts, and treat with an appropriate fungicide.

Preventive Measures

• Space plants 12 to 18 inches apart to encourage airflow and reduce humidity buildup.
• Use well-draining soil and avoid overwatering to prevent root diseases.
• Inspect plants regularly to catch pest or disease problems early.
• Avoid overhead watering to keep foliage dry and reduce fungal risks.

With careful monitoring and good growing practices, Lemon Thyme can stay vibrant, healthy, and productive in the garden for many seasons.

Companion Planting with Lemon Thyme

Thyme is an excellent companion plant that enhances growth, flavor, and pest resistance in many garden plants. Its strong aroma naturally repels common vegetable pests such as cabbage loopers, cabbage maggots, cabbageworms, corn earworms, tomato hornworms, spider mites, and whiteflies. Its small flowers also attract beneficial insects and pollinators, making thyme a valuable addition to any vegetable garden.

Good Companions for Thyme

• Cabbage Family (Brassicas): Thyme helps repel cabbage loopers, whiteflies, and aphids. It works well with broccoli, cabbage, cauliflower, kale, and Brussels sprouts.
• Tomatoes: Plant it near tomatoes to improve their flavor and deter hornworms and whiteflies. It also helps attract pollinators to nearby tomato flowers.
• Eggplant: Thyme’s pest-deterring scent protects eggplants from moths and flea beetles.
• Roses: Thyme planted near roses helps reduce black spot and aphid problems thanks to its antifungal properties.
• Herbs with Similar Needs: Lavender, rosemary, sage, oregano, and marjoram all prefer dry, sunny conditions and pair well with thyme. Companion Planting with Herbs: A Guide to Smart Pairings

Bad Companions for Thyme

• Basil: Basil prefers richer, more consistently moist soil and partial shade, which clashes with thyme’s dry, sunny preferences.
• Cilantro: Cilantro likes cooler temperatures and more water, making it a poor match for thyme.
• Chives: Chives require moister soil and more frequent watering than thyme tolerates.
• Mint: Mint is aggressive and spreads rapidly, often choking out smaller, slower-growing herbs like thyme. It also prefers damper conditions.

Frequently Asked Questions about Lemon Thyme

Will Lemon Thyme Spread?

Yes, lemon thyme has a spreading, mounding habit. It can gradually extend outward to form a dense mat, especially when grown in ideal conditions. While it won’t take over a garden aggressively, it may spread up to 18 inches or more, making it useful as a ground cover between pavers, along walkways, or over slopes.

Does Lemon Thyme Come Back Every Year?

Lemon thyme is a perennial herb in USDA zones 5–9. In these regions, it will return each year with proper care. In colder climates, it may need winter protection or be grown in containers and brought indoors to survive frost. With evergreen foliage in mild winters, it provides year-round interest in the garden.

What Is the Difference Between Lemon Thyme and Regular Thyme?

Lemon thyme (Thymus citriodorus) differs from common thyme (Thymus vulgaris) primarily in its aroma and flavor. Lemon thyme has a bright citrusy scent and taste, while regular thyme has a more earthy, pungent, and slightly minty profile. Lemon thyme also tends to have a softer, more ornamental growth habit with greener or variegated foliage, depending on the variety.

What Not to Plant Next to Lemon Thyme?

Avoid planting lemon thyme next to herbs or vegetables that require consistently moist or rich soil, such as basil, cilantro, chives, and mint. These plants have different water and nutrient needs and may not thrive when grown alongside drought-tolerant lemon thyme. Mint, in particular, is aggressive and can crowd out thyme.

Where Is the Best Place to Plant Lemon Thyme?

The ideal location for lemon thyme is a sunny, well-drained area with lean, sandy or rocky soil. It performs beautifully in herb gardens, rock gardens, raised beds, containers, along borders, or between stepping stones. Ensure it receives at least 6 hours of sunlight per day and has good air circulation.

What Does Lemon Thyme Keep Away?

Lemon thyme is known to repel several common garden pests due to its strong essential oils. It helps deter mosquitoes, cabbage worms, whiteflies, and aphids. Planting it near vegetable beds, patios, or doorways can provide mild natural pest protection while attracting beneficial pollinators like bees and butterflies.