I absolutely love growing lemon verbena plants! It has a very strong lemon scent which is much more intense than that of other herbs. Inhaling transports you to a lemon grove in the Mediterranean where you feel uplifted, refreshed and awake.
Lemon verbena is a type of aromatic shrub that is part of the genus Aloysia, which contains more than 30 species. All of the species in this genus are native to North and South America. The botanical name for this plant has changed over the past two centuries since it was brought to England. The lemon scent of Verbena citriodora gives it the alternative name Verveine citronelle in France. This Spanish researcher determined that this plant belonged to the genus Aloysia because its fruit separates into two nutlets, as opposed to the four nutlets that result from fruits of Verbena species. The plant was previously known as A. citriodora but was moved to the genus Lippia in the early nineteenth century. The genus Lippia is named for Lippi, an Italian botanist. Lemon verbena has been reassigned to the genus Aloysia as A. triphylla. The species name is based on the plant’s leaves, which grow in whorls of three. The whorls on some plants consist of four leaves instead of the usual three. This occurs occasionally, and may happen on all the stems of a plant, or just on certain ones.
Loose, well-drained soil that is rich in organic matter is the best type of soil for lemon verbena to grow in. However, of the two characteristics, drainage is more important. Lemon verbena does not do well in either clay soils or very acidic soils. The best remedies seem to be a lot of sand and a little lime, respectively. If the roots of lemon verbena are constantly wet, it will rot.
Lemon verbena can manage with a variety of watering schedules as long as the drainage is good. If you’re unsure how much water your plant needs, it’s better to err on the side of giving it less rather than more. The best way to determine how much water your plant needs is to keep an eye on it and get to know its watering needs over time. If you live in a colder climate than Zone 9, you should stop watering your lemon verbena plant a few weeks before freezing weather is expected. This will allow the plant to harden off and prevent the roots from freezing. The plant doesn’t need much water when it’s dormant, whether it’s kept inside or outside.
Fertilize lemon verbena as you would any other herb plant: as often as every two weeks indoors or every four weeks in the garden when the plant is growing vigorously, less during periods of slower growth and not at all during dormancy. Some gardeners question whether it is the fertilizer or just the water that stimulates growth in spring after winter dormancy.
Lemon verbena grows best in full sun in northern regions, and even does better when reflected off a white fence or greenhouse wall. It thrives better near the equator in its native latitude where there is at least some shade during part of the day.
Lemon verbena flowers and sets two-seeded fruit best in southern zones where the growing season is long, or in more northern zones under lights. Although the length of the growing season is a factor in whether a lemon verbena plant will produce flowers, other aspects such as stem length also play a role. Gardeners who regularly prune their lemon verbena plants heavily are less likely to see flowers. The flowers are small, numerous, and white to pale purple. They are clustered along the last few inches of the main stem and on short stems in the leaf axils.
Pruning herbs encourages new growth at various points along the stem. For lemon verbena, new growth mainly occurs at the whorl of leaves immediately below the cut. This habit of frequent, severe pruning gives the topiary gardener quite a bit of control over the plant, but it also means that the plant will become leggy and will need to produce more foliage.
Planting Lemon Verbena
Lemon verbena can be difficult to propagate, so it is best for new home gardeners to start with a well-established shop-bought plant. Plant lemon verbena outside after you are sure that there will be no more frosts and only warm weather. Pick a location for your lemon verbena that gets a lot of sun and has soil that won’t let the plant dry out. The plant can be sensitive to changes in temperature, so try to find a spot that is sheltered from any drafts.
Lemon verbena can survive outside in cold climates if it is in a full sun location and is protected from frost with a deep winter mulch of woodchip, bark, or straw. If you don’t want to plant your lemon verbena in soil, you can put it in a container with loam-based compost. Containers can then be brought inside over winter. Short of indoor space? You should use large heavy pots that will provide some insulation, and move your containers to a sheltered area during the winter months.
Make sure the planting hole or container you use for lemon verbena is big enough to accommodate the root ball. Put the plant in the hole so that the bottom of the stem is the same depth as it was in the pot. If stems are planted too deep, they may rot.
Think about the climate you live in and how you want to use the plant when it comes to spacing. Lemon verbena prefers hot climates and can grow up to 8ft by 8ft. Regularly harvested plants should be spaced 12 inches to 30 inches apart and kept in shape with regular trimming. Growing lemon verbena in a container will cause the plant to be shorter, only growing to be 2-3 feet tall.
Moisture-Retentive Soil is often Recommended
Gardeners often grow lemon verbena in pots so that it can be moved indoors or outdoors depending on the weather. The advantage of this is that you don’t have to replant every year and the plant experiences less trauma, however the soil inside a pot heats up and cools down much faster than ground soil, so the plant can still go through some stress. Choose a large pot so the roots have plenty of space to grow, and so soil temperature won’t be affected too much by short-term changes in air temperature. Decreasing the effect can be done my burying the pot in the garden during the plant’s outdoor sojourn. The negative aspect of this strategy is that the roots could grow out of the drainage holes and be damaged when the plant is removed from the pot in early fall. Root breakage can significantly slow down growth and will probably cause leaves to fall off. Trimming the plants back a bit may help them to adjust to the loss of roots.
The temperatures that lemon verbena can survive differ depending on the source, with some saying it can’t survivebelow 14 degrees and others saying it can’t survive below 22 degrees. (Andy was) very surprised Andy Van Hevelingen of Newberg, Oregon was very surprised that an uncovered lemon verbena that he had survived a single night at 3 degrees. Conditions were optimal: the stems were protected from wind, the soil was completely dry around the roots, and the decrease in temperature was gradual over a few weeks so that the plant had time to harden off and become fully dormant. If you want your plant to survive near the edge of its hardiness range, it’s important to protect it from wind. You can do this by wrapping the dormant top with weatherproof plastic foam or burlap, or by covering it with mulch. In order to protect her lemon verbena plants from the cold weather, Kae Snow-Stephens from Shreveport, Louisiana puts them in plastic garbage bags. These plants have been able to endure overnight temperatures as low as 22 degrees without losing leaves or slowing their growth.
Choose a pot that is at least 12 inches in diameter so that the roots have plenty of space to grow and so that the effects of short-term changes in air temperature on soil temperature are minimized.
Lemon verbena that winters outdoors is one of the first plants to emerge from dormancy for some gardeners, but others in similar climates report that growth resumes later in lemon verbena than in other perennials. If it’s spring and you’re wondering if your lemon verbena will come back, you can test for signs of life by bending or clipping off the ends of the dormant woody stems. Although the wood may be dry and brittle, the stems closer to the base of the plant are still alive. One experienced gardener recommends not testing if a branch is dead by trying to bend it because the dead wood protects what is alive; if your curiosity can survive the wait, the answer will come eventually in the form of new growth (or its continued absence).
Lemon verbena grows best in a soil that is well-drained and able to retain moisture, while also being moderately fertile. The ideal pH level for soil is neutral to slightly acidic. Loam-based compost is beneficial for container-grown plants because it provides a nutrient boost.
Water your lemon verbena plant with nitrogen-rich liquid fertilizer every few weeks to keep it healthy and growing.
Lemon verbena plants can get big and woody over time. Trimming young leaves and stems regularly will help keep plants productive, but after a while, branches may become spindly and congested. To encourage compact, bushy growth, lemon verbena plants should have their branches cut back by a third in early spring.
Lemon verbena is difficult to propagate from seed. Seeds that come from reliable sources and have been produced in cooler climates are not always viable. The best way to propagate lemon verbena is via taking softwood or semi-ripe cuttings from the plant, similar to how you would with other woody herbs such as rosemary and thyme. Cut 4-6 inches of new growth from a softwood plant in spring. Remove the lower leaves and place the stem into a pot filled with a 50:50 mix of compost and perlite or horticultural grit. Keep the cuttings moist and humid until roots form.
Cutting softwood can be done by placing it in a glass of water, allowing you to see the root development more closely. Make sure to change the water every few days. After the roots are established, transplant the cuttings into a larger pot and continue growing until they are well established. In colder climates, it’s best to keep young plants sheltered for a while longer and acclimate them to outside conditions. Cutting that are semi-ripe can be taken in the later summer or early fall. They should be kept indoors until the spring of the next year.
Harvesting and Storing
Lemon verbena leaves are excellent when used fresh. This herb is easy to dry and retains its signature sherbet lemony scent for a long time.
Fresh young leaves have the best lemon flavor. Leaves can be harvested from the plant once it is well established and is about 10-12 inches tall. You should only pick a few leaves when you’re making a fresh herbal tea. Cut the stems back 4-6 inches to encourage bushy growth for a larger harvest.
Storing fresh herbs: -Wrap stems in damp kitchen paper -Place stems in a glass of water To dry leaves quickly, hang bunches of stems up or lay them out on a flat surface in a cool, ventilated dark place. Dry leaves can be stored for 1-2 years by crumbleing them and keeping them in an airtight container.
When growing lemon verbena, the main issues are getting the soil right and protecting plants over winter. Aim for rich, well-drained soil that retains moisture. Heavy, wet soils can cause problems for plants over winter, including soggy roots that may rot or freeze. A dry mulch like straw, wood chip, or bark will protect roots and prevent soils from becoming waterlogged. It is essential that plants have direct sun in order to develop properly.
Many gardeners and commercial growers refuse to have lemon verbena around because they believe it attracts whiteflies and spider mites, which are pests. However, many people in the same climates either experience no such problems or find the pests easy to deal with. If you’re a home gardener with just a few plants and you’re dealing with an infestation of whiteflies or spider mites, you can spray the leaves (top and bottom) with insecticidal soap or a solution of dishwashing liquid (1 teaspoon), vegetable oil (1 tablespoon), and water (1 quart) three times at 10-day intervals. Just make sure to rinse about three hours after application. Indoor plants should be kept away from other houseplants during treatment. Watering the plants twice a week is said to discourage mites from returning.
Pythium root rot is a fungi that lives in poorly drained, wet soils or soils that are over irrigated or have experienced prolonged heavy rainfall. The symptoms of this plant disease are reduced growth, wilting, and plant death. To prevent pythium root rot, lemon verbena should be planted in well-drained fertile soils and watered consistently to keep the soil moist, but not wet. Soil solarization, or exposure to the sun, is a good non-chemical treatment for affected soils or areas. Areas that cannot be treated with solarization can be treated with an appropriate fungicide. Always check the label.