Do Citronella Plants Come Back? - Plant Care Guide

Whether citronella plants come back depends entirely on the specific species you're referring to and your USDA Hardiness Zone. The term "citronella plant" commonly refers to a scented geranium (Pelargonium citrosum) which is a tender perennial. This means it will only reliably return year after year in warm, frost-free climates (typically USDA Zones 9-11). In colder zones, it is treated as an annual unless brought indoors for winter. True citronella grass (Cymbopogon nardus or Cymbopogon winterianus) is also a tender perennial, hardy in similarly warm climates.

What is typically sold as a "citronella plant"?

What is typically sold as a "citronella plant" in garden centers and nurseries (especially in temperate climates outside of the tropics) is most often a scented geranium, specifically Pelargonium citrosum, or a related Pelargonium hybrid. This plant is marketed for its lemon-scented foliage, which is often associated with mosquito repellent properties.

Here's a breakdown of what is commonly sold as a "citronella plant":

1. Pelargonium citrosum (Scented Geranium):

   • Common Name: "Mosquito Plant," "Citronella Geranium," "Citrosa Geranium."
   • Appearance: Features deeply lobed, lacy green leaves that release a strong, citrusy (lemony-geranium) fragrance when crushed or brushed against. It grows as an upright, bushy plant, often reaching 1-2 feet tall and wide. It may produce small, inconspicuous pinkish-lavender flowers.
   • Origin: This plant is widely believed to be a hybrid, possibly involving a cross between Pelargonium graveolens and Cymbopogon nardus (true citronella grass), though its exact genetic lineage is debated. However, it's firmly a Pelargonium species.
   • Repellent Properties: While its leaves contain compounds similar to citronella oil (like citronellal, geraniol), the plant itself does not actively repel mosquitoes simply by existing. Mosquitoes are only repelled if the leaves are crushed and the oils are rubbed directly onto the skin. The whole plant growing nearby offers very limited repellent effect.
   • Hardiness: This "citronella plant" is a tender perennial. It is reliably hardy outdoors only in USDA Hardiness Zones 9-11, where it can grow back each year. In colder zones, it will die with the first hard frost and must be treated as an annual or brought indoors for winter protection.

2. True Citronella Grass (Cymbopogon nardus or Cymbopogon winterianus):

   • Common Name: "Lemongrass," "Citronella Grass."
   • Appearance: This is a tall, clumping, grass-like plant, resembling ornamental grasses or edible lemongrass. Its leaves also have a strong, lemony fragrance when crushed.
   • Origin: Native to tropical regions of Asia. This is the plant from which commercial citronella oil (used in candles, sprays) is primarily extracted.
   • Repellent Properties: Like the Pelargonium, the intact plant offers little active mosquito repellent in a garden. The essential oil needs to be extracted and concentrated for effective use.
   • Hardiness: Also a tender perennial, reliably hardy only in USDA Hardiness Zones 10-11 (some sources say Zone 9 for C. nardus). It will not survive frost and must be treated as an annual or overwintered indoors in colder climates.

So, when asking "Do citronella plants come back?", the common garden center "citronella plant" (Pelargonium citrosum) is a tender perennial that returns only in frost-free regions.

What is the hardiness of the commonly sold "citronella plant" (Pelargonium citrosum)?

The hardiness of the commonly sold "citronella plant" (Pelargonium citrosum) is that of a tender perennial, meaning it is sensitive to cold temperatures and will only reliably return year after year in frost-free or very mild winter climates. Its ability to "come back" depends entirely on your specific USDA Hardiness Zone.

• USDA Hardiness Zones 9-11 (Tender Perennial):

  • In these warmer zones (e.g., Southern California, Florida, parts of the Gulf Coast), the citronella plant will typically survive winter outdoors in the ground and regrow from its rootstock or perennial stem base in spring.
  • It may experience some dieback of foliage during cooler periods, but the main plant will persist.

• USDA Hardiness Zones 8 and Colder (Treat as Annual or Overwinter Indoors):

  • In Zone 8, the citronella plant may sometimes survive a very mild winter if heavily mulched and protected, but its survival is not guaranteed.
  • In Zones 7 and colder, it is unequivocally not hardy outdoors. The plant will die with the first hard frost.
  • Options for Colder Climates:
    • Treat as an Annual: Plant it each spring, enjoy its scent and foliage through summer, and accept that it will die with winter.
    • Overwinter Indoors: Bring the plant indoors before the first hard frost. This allows you to keep it as a perennial. (See specific section on overwintering).

Temperature Sensitivity:

• Frost Intolerance: Pelargonium citrosum is highly intolerant of freezing temperatures. Even a light frost (temperatures dipping to 32°F / 0°C) can severely damage or kill the foliage, and a hard freeze (prolonged temperatures below 28°F / -2°C) will often kill the entire plant.
• Ideal Temperatures: It thrives in warm, sunny conditions, typically above 50°F (10°C).

In summary, the commonly sold "citronella plant" (Pelargonium citrosum) is a tender perennial that only comes back reliably in USDA Zones 9 and warmer. In colder zones, active intervention (overwintering indoors) is required to ensure it returns.

How can I overwinter a citronella plant indoors in colder climates?

To overwinter a citronella plant indoors in colder climates and ensure it comes back next spring, you need to provide a suitable indoor environment that protects it from freezing temperatures and allows it to rest. This strategy transforms a tender perennial into a reusable plant for multiple seasons.

Here's how you can overwinter a citronella plant indoors in colder climates:

1. Timing is Key:

   • Before First Frost: Bring your citronella plant indoors before the first hard frost is expected in your area. Even a light frost can damage or kill the foliage, reducing its chances of survival indoors. Monitor your local weather forecasts.
   • Acclimatization: Ideally, gradually acclimate the plant to indoor conditions by moving it to a shadier outdoor spot for a week, then a protected porch, before bringing it fully inside. This reduces shock.

2. Preparation Before Bringing Indoors:

   • Inspect for Pests: Thoroughly inspect the entire plant (leaves, stems, undersides, soil surface) for any signs of pests (e.g., aphids, spider mites, mealybugs). You do not want to introduce these into your home.
     • Treatment: If pests are found, treat them outdoors with insecticidal soap or neem oil for a week or two before moving indoors.
   • Pruning: Give the plant a light prune to reduce its size, remove any leggy or damaged growth, and shape it. This makes it more manageable indoors and stimulates new growth in spring. Remove any yellowing leaves.
   • Cleanliness: Wipe down the pot to remove any hitchhiking insects.

3. Provide a Suitable Indoor Environment:

   • Light: Place the citronella plant in the brightest location possible indoors, ideally a south-facing window. While it won't be actively growing as much, it still needs light. If light is limited, the plant might go into a semi-dormant state, dropping some leaves. Supplemental grow lights can help maintain vigor.
   • Temperature: Aim for cool, but not freezing, temperatures. An ideal range is 50-60°F (10-15°C). Avoid placing it near heat vents that can dry it out or drafty windows with extreme cold. Unheated sunrooms, basements, or garages with windows are often good choices.
   • Humidity: Indoor air can be very dry due to heating. While geraniums don't demand high humidity, extremely dry conditions can cause leaf crisping. You can mist occasionally or place the pot on a pebble tray with water.

4. Adjust Watering and Fertilizing:

   • Reduce Watering: Significantly reduce watering frequency during winter. Allow the soil to dry out almost completely between waterings. The plant is not actively growing and is very susceptible to root rot if kept too wet. A soil moisture meter can be helpful.
   • Stop Fertilizing: Do not fertilize the citronella plant during its indoor overwintering period. It does not need the extra nutrients while resting.

5. Monitoring:

   • Continue to monitor the plant for pests and diseases throughout the winter. Dry indoor air can sometimes encourage spider mites.

6. Transition Back Outdoors (Spring):

   • Once all danger of frost has passed in spring, gradually reintroduce the citronella plant to outdoor conditions. Start in a sheltered, shady spot and gradually move it into brighter light over 1-2 weeks before placing it in its final sunny location. Repot if needed.

By carefully following these steps, you can successfully overwinter your citronella plant indoors and enjoy its fragrant foliage again next season.

What care do citronella plants need during their active growing season?

During their active growing season (spring through fall), citronella plants (specifically Pelargonium citrosum) need consistent care to encourage vigorous growth and abundant fragrant foliage. These plants are relatively low-maintenance but respond well to optimal conditions.

Here's the care citronella plants need during their active growing season:

1. Sunlight (Crucial):

   • Full Sun: Citronella plants thrive in full sun, meaning at least 6-8 hours of direct sunlight per day.
   • Location: Place them in the sunniest spot in your garden, on your patio, or a bright windowsill. Ample sunlight encourages dense, healthy foliage and the production of their aromatic oils.

2. Watering:

   • Moderate Moisture: Water regularly to keep the soil consistently moist but not waterlogged. Allow the top 1-2 inches of soil to dry out between waterings.
   • Deep Watering: When you water, do so thoroughly until you see water draining from the bottom of the pot (for container plants).
   • Avoid Wet Feet: Ensure good drainage in pots or garden beds. Overwatering is a common killer.
   • Monitor: Use a soil moisture meter to accurately gauge moisture needs.

3. Soil:

   • Well-Draining: Citronella plants prefer well-draining soil.
   • Nutrient-Rich: Use a good quality, all-purpose potting mix for containers or amend garden soil with compost for in-ground planting.

4. Fertilization:

   • Moderate Feeder: Fertilize sparingly. A monthly application of a balanced liquid fertilizer (e.g., 10-10-10 or 5-10-5) diluted to half-strength during the active growing season (spring and summer) is usually sufficient for container plants.
   • In-Ground: In-ground plants may need less, especially if planted in rich soil.
   • Avoid Over-Fertilizing: Too much fertilizer, especially nitrogen, can lead to lush but weak growth.

5. Pruning and Maintenance:

   • Pinching/Pruning: Pinch back the growing tips or prune the plant regularly to encourage a bushier growth habit and prevent legginess. This also promotes more foliage, which is the scented part.
   • Deadheading: Remove any spent flowers (though they are small and not the main attraction) to redirect energy into foliage production.
   • Clean-up: Remove any yellowing, damaged, or dead leaves promptly.

6. Pest and Disease Monitoring:

   • While generally quite robust, watch out for common pests like aphids, spider mites, or whiteflies. Treat with insecticidal soap or neem oil if infestations occur. Good air circulation helps prevent fungal diseases.

By providing consistent sunlight, appropriate watering, and regular pruning, your citronella plants will remain healthy and vigorously produce their fragrant foliage throughout the active growing season.

How effective are citronella plants at repelling mosquitoes?

The effectiveness of citronella plants at repelling mosquitoes is often overstated and generally limited when the plant is left intact. While the essential oil extracted from true citronella grass (Cymbopogon nardus) is a proven mosquito repellent ingredient, merely having the living plant in your garden offers very little protection.

Here's a breakdown of the actual effectiveness of citronella plants at repelling mosquitoes:

1. Intact Plant: Minimal Repellent Effect:

   • Myth vs. Reality: The common belief that placing a citronella plant (either the scented geranium or the grass) on your patio will create a "mosquito-free zone" is largely a myth.
   • Why: The repellent compounds (like citronellal, geraniol) are contained within the plant's cells. They are not actively released into the air in sufficient concentrations to deter mosquitoes simply by the plant's presence.
   • Studies: Scientific studies have repeatedly shown that intact citronella plants (both Pelargonium citrosum and Cymbopogon species) offer negligible mosquito repellent efficacy compared to commercial repellent products or even a simple fan. Some studies indicate they are no more effective than a plain green plant.

2. Crushed Leaves: Limited, Short-Term Repellency:

   • Activation: To release the repellent oils, the leaves of a citronella plant must be crushed, bruised, or torn. Rubbing the crushed leaves directly onto the skin will provide a short-term, localized repellent effect.
   • Limitations: This method is impractical for widespread protection, requires continuous reapplication, and some people may experience skin irritation from direct contact with the plant's oils.

3. Extracted Citronella Oil: Proven Repellent:

   • Commercial Use: The essential oil derived from true citronella grass (Cymbopogon nardus or C. winterianus) is a well-established and effective mosquito repellent ingredient. It is precisely because it contains these active compounds that it is extracted and concentrated for use in citronella candles, sprays, and lotions.
   • Mechanism: These concentrated essential oils, when burned (in candles) or applied topically, create a vapor barrier that mosquitoes dislike, or they interfere with the mosquitoes' ability to detect the human scent.

4. Citronella Candles:

   • Limited Range: Even citronella candles, which burn the concentrated oil, have a very limited range of effectiveness, typically only offering some protection in a very small, still area directly around the candle. The smoke itself often has more repellent effect than the citronella.

Summary Table of Effectiveness:

In conclusion, while the idea is appealing, relying solely on citronella plants in their living form for mosquito control is largely ineffective. For actual mosquito repellency, it's best to use commercial products that contain extracted citronella oil or other proven active ingredients.

What other plants are often mistaken for "citronella plants"?

Several other plants are often mistaken for "citronella plants" due to their similar lemony fragrances or general appearance, creating confusion among gardeners. The most common mix-up is between the scented geranium sold as "citronella" and the actual citronella grass.

Here are other plants often mistaken for "citronella plants":

1. Lemongrass (Cymbopogon citratus):

   • Confusion: This is edible lemongrass, a common culinary herb. It looks very similar to true citronella grass (Cymbopogon nardus or C. winterianus) and also has a strong, fresh lemon scent when crushed.
   • Distinction: While it contains some similar compounds, it is a different species used primarily for cooking (especially in Asian cuisine) rather than insect repellent. True citronella grass is generally more robust and coarser than edible lemongrass.
   • Hardiness: Also a tender perennial, generally hardy in USDA Zones 9-11.

2. Lemon Balm (Melissa officinalis):

   • Confusion: A member of the mint family, lemon balm has bright green, crinkly leaves and a strong, sweet lemon scent. It's often grown as a culinary and medicinal herb.
   • Distinction: Looks very different from the geranium (it's a leafy herb, not a geranium) and the grass. Its leaves are more rounded and textured.
   • Hardiness: A very hardy perennial, often growing in USDA Zones 4-9, and can be quite vigorous/invasive.

3. Lemon Verbena (Aloysia citrodora):

   • Confusion: Known for having one of the strongest and purest lemon scents among plants, often used in teas and culinary dishes.
   • Distinction: Has long, slender, lance-shaped leaves. It's a woody shrub. Looks distinctly different from either the geranium or the grass.
   • Hardiness: A tender perennial, generally hardy in USDA Zones 8-10, sometimes Zone 7 with protection.

4. Lemon Thyme (Thymus citriodorus):

   • Confusion: A creeping or mounding herb with small, fragrant leaves that have a distinct lemon-thyme scent.
   • Distinction: Its small, intricate leaves and growth habit are very different from the broader leaves of the geranium or grass.
   • Hardiness: A hardy perennial, typically USDA Zones 5-9.

5. Eucalyptus (Eucalyptus citriodora - Lemon-Scented Gum):

   • Confusion: The leaves of this tree species have a powerful, pungent lemon-eucalyptus aroma.
   • Distinction: This is a large tree! Its long, slender, blue-green leaves are distinctly different from the geranium or grass.
   • Hardiness: Varies greatly by species, but Lemon-Scented Gum is generally for warmer climates (Zone 9+).

The common thread among these plants is their delightful lemony scent, which often leads to them being grouped with or confused for the "citronella plant." While many of them are wonderful garden additions with their own uses, it's important to know their true identity and capabilities.

How can I use citronella plants for actual mosquito deterrence?

To use citronella plants for actual mosquito deterrence, you need to actively extract and utilize the volatile repellent compounds from their leaves, as simply having the intact plant in your garden is largely ineffective. The plant's inherent ability to repel mosquitoes only becomes apparent when its oils are released and concentrated.

Here's how you can use citronella plants for actual mosquito deterrence, moving beyond just having the plant present:

1. Crush and Rub Leaves Directly on Skin (Short-Term, Localized):

   • Method: This is the most direct way to get the repellent oils from the plant. Pick a few leaves from your citronella plant (Pelargonium citrosum or true citronella grass). Crush or bruise them vigorously in your hands to release the aromatic oils. Then, rub the crushed leaves directly onto exposed skin areas.
   • Effectiveness: Provides a noticeable, though short-term (often 20-30 minutes), localized mosquito repellent effect.
   • Cautions:
     • Skin Irritation: Some individuals may have skin sensitivities or allergic reactions to direct contact with plant sap or oils. Test a small patch of skin first.
     • Impractical: This method is labor-intensive and requires continuous reapplication, making it impractical for prolonged or widespread protection.

2. Make a Topical Repellent Spray/Lotion (DIY, with Caution):

   • Method: You can attempt to make your own repellent by steeping a large quantity of crushed citronella plant leaves in a carrier oil (like witch hazel, vodka, or olive oil) for several weeks, then straining and using the infused liquid as a spray or diluting it further into a lotion.
   • Effectiveness: The effectiveness of DIY extractions will be highly variable and generally less potent than commercially produced repellents using concentrated essential oils. The concentration of active compounds will be much lower.
   • Cautions:
     • Consistency: Achieving a consistent, effective concentration is difficult without specialized equipment.
     • Preservation: DIY solutions may not be shelf-stable and could spoil.
     • Safety: Always test on a small area of skin.

3. Burn Dried Plant Material (with extreme caution and proper ventilation):

   • Method: Some people try to burn dried citronella plant leaves or stems, similar to how citronella coils work. The heat releases the aromatic compounds into the air.
   • Effectiveness: Can provide some localized deterrence, but the smoke itself might be more effective than the citronella compound.
   • Extreme Cautions:
     • Fire Hazard: Burning dry plant material poses a significant fire risk.
     • Smoke Inhalation: Inhaling plant smoke can be irritating or harmful. Only do this outdoors in a very well-ventilated area, and do so very sparingly.
     • Inefficiency: It's often an inefficient way to release the compounds compared to purpose-made citronella candles or diffusers.

Best Practice:

• For reliable and safe mosquito deterrence, it is generally much more effective to use commercial mosquito repellent products that contain either extracted citronella essential oil (from Cymbopogon grass) or other proven active ingredients (like DEET, Picaridin, Oil of Lemon Eucalyptus). These products offer controlled concentrations and tested efficacy.
• Grow citronella plants for their ornamental value and fragrant foliage, and rely on commercial repellents or other methods (like fans, screens) for active mosquito control.

By understanding the limitations and the need for active extraction, you can approach using citronella plants for mosquito deterrence more realistically and safely.