When it comes to lemon-scented herbs, lemon verbena has the most intense concentration of oils per square inch of plant material. Devoid of bitterness, this plant is beloved as an additive to drinks, baked goods, or anywhere you might use lemon zest. The spear-shaped leaves of lemon verbena grow quickly in hot summer weather, replenishing the plant as you harvest throughout the growing season. For those who live where lemon verbena is hardy, the plant can become an anchoring shrub in your landscape, ready to release its citrusy aroma whenever you brush by.
- Botanical Name: Aloysia citriodora
- Common Name: Lemon verbena, lemon beebrush, vervain
- Plant Type: Tender perennial in frost-free zones
- Mature Size: Six feet where hardy
- Sun Exposure: Full sun
- Soil Type: Rich and moist
- Soil pH: Slightly acidic; 6.1-7.0
- Bloom Time: Late summer
- Flower Color: Purple buds open to white blossoms
- Hardiness Zones: USDA growing zones 8-11
- Native Area: South America, especially Chile and Peru
How to Grow Lemon Verbena
The fragrance and size of lemon verbena plants make them a valuable addition to the back of the sunny herb border. Set your plants out at the same time you plant tomatoes, coleus, and other warm weather lovers. A site with full sun, rich soil, and regular moisture will result in quick growth for the harvest.
Lemon verbena needs full sun, similar to what roses or a vegetable garden would need. Situate your lemon verbena plants where they won't be cast in the shade of a neighboring tree or building. Plants that grow indoors as houseplants may need supplemental artificial lighting to prevent lanky growth and leaf drop.
Lemon verbena does well in rich garden loam, but average soil is also tolerated. Good drainage is important for healthy lemon verbena plants, so in areas with clay you must plant them in raised beds or containers.
Lemon verbena needs regular irrigation. A lack of water leads to plant stress, leaf drop, and insect pest infestation. Keep the surface of the soil moist, but don't oversaturate the plants. Aim for a moisture level that resembles that of a wrung-out sponge. An exception is plants spending the winter months indoors: they may be kept on the dry side.
Temperature and Humidity
In its native South America, lemon verbena plants grow in a sunny, frost-free climate. Temperatures below 40 degrees Fahrenheit will trigger leaf drop and dormancy. Plants do well in dry or humid climates.
Lemon verbena is a departure from other herbs in that it appreciates a regular fertilizing schedule to keep it lush and vigorous. Feed plants in the spring with an all-purpose fertilizer. Watering each time with compost or manure tea during the growing season will keep plants productive.
Potting and Repotting
Pot up your lemon verbena in rich potting soil. Amend the soil with leaf mold or composted manure to ensure a healthy start. Potted plants moving indoors for the winter will lose many leaves. Repot plants in the spring before new growth begins.
Propagating Lemon Verbena
Lemon verbena is propagated in the same way as other woody herbs like rosemary and lavender, by taking semi-ripe cuttings. Snip a flower-free stem above a leaf node. Remove all but the top two set of leaves, and insert the cutting into moist, sterile potting mix. Keep moist until new leaves begin to form. Transplant into a sunny site with good drainage.
Toxicity of Lemon Verbena
According to the ASPCA, lemon verbena is mildly toxic to dogs, cats, and horses, causing stomach upset and colic. The small amounts that one would use in cooking do not present a problem, but ingestion of the concentrated oil causes toxic effects.
Lemon verbena plants growing in containers rarely exceed two or three feet in height, but outdoors in frost-free climates the shrubs can exceed eight feet. Over time, the shrubs can get woody and lanky. Cut plants back by half in early spring to encourage compact, bushier growth.
You can harvest the leathery leaves of lemon verbena anytime for recipes. Because the leaves are tough, you must mince them finely if you plan to consume them. You can also infuse sauce, oil, sugar or tea with whole leaves. The tiny blossoms of lemon verbena also carry its heady scent, and can be used in the same way as the leaves.
Being Grown in Containers
Growing lemon verbena in a container is an ideal way to cultivate the plant all year in colder regions, Container-grown lemon verbena also stays a more manageable size than plants grown in the ground. Choose a potting soil enriched with time-release fertilizer to give plants a head start. Keep the container in full sun, and water daily. Bring your plant indoors or to a greenhouse when temperatures drop below 40 degrees Fahrenheit.
Growing From Seeds
Lemon verbena flowers produce few viable seeds. Those that are produced rarely germinate, and therefore gardeners should start with young lemon verbena plants rather than seeds.
Lemon verbena growing outdoors in full sun and rich soil is rarely plagued by pests. When brought indoors to overwinter, spider mites and whiteflies seem to be drawn to the plants as they struggle to acclimate to weaker light and less humidity. Mist plants frequently to disrupt the dry conditions that spider mites enjoy. Put out yellow sticky traps if whiteflies congregate.
Lemon Verbena vs Lemon Balm
Lemon balm (Melissa officinalis) and lemon verbena have similar uses in the kitchen. Lemon balm is a hardy perennial, and will return in the landscape each year in zones 3-7. As a member of the mint family, lemon balm spreads vigorously, and can become invasive. On the plus side, it is more shade tolerant than lemon verbena. You can distinguish lemon balm from lemon verbena by its rounded, wrinkled leaves on low growing plants. Although both plants have a strong lemon scent and flavor, lemon balm has a somewhat astringent tone whereas lemon verbena is more floral.