Citronella plants (Pelargonium graveolens Citrosa) are a popular scented geranium that features large, wrinkled, lacy green leaves that complement its pink petals. Citronella geranium grows easily in pots and when planted in the ground—with a bushy spread of 2 feet tall and wide.
Its most sought-after feature is the lemony fragrance emitted from its leaves. Although many other plants have a citrus fragrance, the citronella geranium is heavily marketed and has gotten a reputation for repelling mosquitoes. If you plan on adding this plant to your gardens, keep in mind that it is toxic to dogs and cats.
Do Citronella Plants Repel Mosquitoes?
The fresh lemony fragrance of citronella scented geraniums can add to the enjoyment of outdoor activities. When leaves are brushed up against or crushed they release a pleasant citrus aroma. Studies completed by the National Institutes of Health, however, find no evidence to suggest this plant actually repels mosquitoes. The fragrance is supposed to ward off pests with leaves that continuously release an essential oil they don't like. While this oil is present in lemongrass(Cymbopogon citratus) the study found no evidence of citronella essential oil in the citronella scented geranium, itself.
|Common Name||Citronella Plant, Mosquito Plant|
|Botanical Name||Pelargonium graveolens Citrosa|
|Plant Type||Herbaceous perennial|
|Mature Size||1 to 2 feet tall and wide|
|Sun Exposure||Full to part sun|
|Soil Type||Well-drained sandy loam|
|Soil pH||5.8 to 6.3|
|Flower Color||Pink, purple|
|Hardiness Zones||9 to 11|
|Native Area||South Africa|
Citronella plant is a low-maintenance plant with a shrubby growth habit. Once established, it's drought tolerant and fully evergreen in its hardiness zones. Northern growers can overwinter these plants in pots or grow them as annuals in the summer garden.
To plant citronella in a pot, choose one at least 12 inches deep and twice as wide as the root ball. Use a nutrient-rich soil but one that is light enough to drain well. Potting soil mixed equally with sphagnum moss and sand is a good combination.
In northern growing zones, plant citronella in the garden when overnight temperatures remain steady at 50 degrees Fahrenheit or above. Set plants 18 to 24 inches apart in fertile, well-draining loam. Amend soil with compost or other organic material, when needed.
Seeds can be sown directly in the ground by sprinkling them lightly over the soil one to two weeks after the final frost when the soil has warmed. For an earlier start, sow seeds indoors six to eight weeks before the final frost. Thin outdoor seedlings to 18 inches apart and indoor plants to one seedling per pot.
In its hardiness zones of 9 to 11, transplant citronella in early spring.
Citronella plants need six hours of full sunlight, daily, but benefit from afternoon shade, especially in southern growing zones.
This plant adapts to soil type as long as it drains well, but performs best in slightly acidic, sandy, or chalky loam with a pH level of 5.8 to 6.3.
Water potted plants regularly throughout the growing season. Check the top inch of soil every few days and irrigate when it's dry. For in-ground plants, water regularly until established then once every other week. Mildly drought-tolerant, garden-grown citronella does not require much water. However, if leaf tips and edges start to turn brown and crispy, increase watering to once a week.
Temperature and Humidity
Citronella are hardy plants that tolerate a range of temperatures from 30 to 90 degrees Fahrenheit. When temperatures fall outside this range, damage can occur. Garden plants benefit from afternoon shade in southern zones when heat remains high for extended periods. Humidity levels of 40 percent or higher benefit this native to the tropics.
Citronella plants don't require a lot of feeding, but the application of a liquid NPK 20-20-20 fertilizer can benefit young and potted plants. Dilute fertilizer by half strength and feed plants once every two to three weeks.
Encourage bushy growth and a full shrubby appearance by pinching out the growing tips of citronella plants throughout the growing season.
To grow citronella plant from a cutting, gather a snipper, a small 4-inch pot, and a well-draining potting mix. Rooting hormone and a plastic covering for the pot are optional.
- Take a cutting with at least four leaves from the citronella plant's new growth
- Remove all but the top two leaves making sure to keep two leaf nodes at the base of the stem.
- Fill a 4-inch pot with a well-draining fertile potting mix.
- Dip the base of the cutting in rooting hormone covering the two nodes at the bottom. This step is not necessary but can aid root development.
- Use your index finger or a pencil to make a hole in the center of the pot.
- Insert the cutting into the hole leaving the top leaves above soil level.
- Lightly tamp soil around the stem to keep the cutting upright.
- Place a plastic dome over the cutting to improve humidity. Alternatively, you can mist the leaves every few days.
- Place the cutting in a sunny location and keep the soil moist. Roots should establish in about one month. Check by gently pulling on the stem. Resistance indicates roots have formed and the plant can be moved to a larger pot or set out in the garden.
Citronella cuttings also root in water. Place a new growth cutting in a small container of clean water with leaves above water level and nodes submerged. Place it in a warm, sunny spot and change the water weekly. Look for roots to establish in about 4 weeks.
How to Grow Citronella From Seed
Citronella is more often purchased as a potted nursery plant, but is grown easily from seed.
Start Seeds Outdoors
- Wait until the ground has warmed about two weeks after the final frost depending on the growing zone.
- Choose an outdoor location with at least six hours of sun daily.
- Scatter seeds over the soil and cover lightly.
- Keep soil moist to aid germination.
- Thin garden plants to 18 inches apart when seedlings reach about 1 inch tall.
Start Seed Indoors
- Fill small 4-inch pots or a seed starting tray with a lightly moistened potting mix. Equal parts potting soil, sphagnum moss, and sand are a good combination.
- Scatter several seeds on top of the medium and cover lightly.
- Place a plastic dome or covering over the pot or tray to aid germination.
- Set them in a warm, sunny spot and keep them moist.
- When seedlings emerge, remove plastic and thin plants to one or two per pot.
- Separate seedlings and plant up into pots one or two sizes larger, as needed.
Potting and Repotting Citronella
As annuals in northern growing zones, purchased citronella geraniums shouldn't need to be repotted more than once, even if you plan to overwinter indoors. Keep in mind the mature size of the plant at around 2 feet tall and wide and choose a pot large enough to accommodate.
Citronella is fairly drought tolerant so any type of pot, including clay and ceramic, is okay provided it has good drainage. The container needs to be 12 inches deep and twice the width of the rootball. Use a light potting mix that drains easily.
Citronella plants brought indoors during winter months can last several years. Move potted plants inside to a warm, sunny window when nighttime temperatures remain below 45 degrees Fahrenheit. Remove dead or damaged leaves and prune stems back by as much as one-third, making your cuts just above a leaf node. Irrigate deeply but less frequently, allowing the soil to dry out slightly between waterings. Feed citronella once or twice during winter with a liquid houseplant fertilizer diluted to half strength.
Common Pests and Plant Diseases
Scented geraniums are relatively disease free but they do attract sap-sucking pests like whitefly, aphids, weevils, leafhoppers, and mealybugs. A strong spray of water can eliminate problems when discovered early. If your plant becomes infested, you may need to repot it with fresh planting material and treat it with repeat applications of insecticidal soap until the pests are gone.
How to Get Citronella to Bloom
In its hardiness zones of 9 to 11, the citronella plant remains evergreen and can bloom year-round.
What Do Citronella Plant Flowers Look and Smell Like?
Small flowers open in clusters with five lavender-pink petals, similar to the flowers of zonal geraniums. A broad dark purple mark brushes the uppermost petals for a subtle but striking two-toned look. Fragrance comes only from the foliage so the flowers are unscented.
How to Encourage More Blooms
Dead head spent flowers and pinch back growing tips throughout the season to add fullness to your plant. A balanced liquid fertilizer reduced to half strength can be applied every three weeks.
Common Problems With Citronella
Citronella scented geraniums are sturdy plants that aren't troubled by many problems. However, this plant does require some maintenance to reach its best appearance.
Thin, Leggy Appearance
Plants that receive fewer than six hours of sunlight may extend toward available light giving them a straggly, leggy appearance. Plant or place pots where they receive adequate light. Regularly pinch back growing tips throughout the season to encourage bushier growth.
Brown Leaf Tips and Edges
Citronella plants are fairly drought-tolerant but do need regular watering, especially during hot, dry periods. Brown leaf tips and edges are signs the plant is dry. Water deeply and consider watering more frequently.
Does citronella really repel mosquitos?
It does not, according to the National Institutes of Health. Citronella essential oil, the oil that repels mosquitos, is found only in lemongrass, an entirely different species.
Are citronella plants perennials?
The citronella plant is a perennial only in USDA hardiness zones 9 to 11. It is grown as an annual in northern zones but can be overwintered for several years as a potted plant.
Is citronella safe to touch?
Yes, unless you are a person with a specific allergy to geraniums. Brushing up against the plant and crushing the leaves are the best ways to release the pleasant lemony fragrance.
What is the difference between citronella plant and citronella grass?
Citronella plant is a scented geranium and an entirely different species from lemon/citronella grass. While both are highly fragrant, only lemon grass contains the essential oil of citronella which is attributed to repelling mosquitoes.
Scented Geranium. American Society for the Prevention of Cruelty to Animals.
Essential oil analysis and field evaluation of the citrosa plant "Pelargonium citrosum" as a repellent against populations of Aedes mosquitoes. National Library of Medicine.