Lemongrass can die for several reasons ranging from cold weather to a fungal infection and lack of nitrogen.
Whether you just planted your lemongrass or you’ve enjoyed using its leaves in recipes for several seasons, it’s disheartening to wake up and discover that it’s dying.
We’ll cover the most common causes of lemongrass decline and how to fix it.
11 Reasons Why Your Lemongrass Plant Is Dying
You can deduce the reason why your lemongrass plant is dying into three categories:
- Environmental conditions
- Insect infestation
- Fungal infection
We’ll cover each of these categories below, with environmental conditions having the greatest potential for things to go wrong with your lemongrass plant.
1. Planted Too Early
- Lemongrass is native to warm regions in southeast Asia. For this reason, they’ll die if you plant them too early in the United States before the last frost.
- If you live in USDA zones nine to eleven, you’re in luck because your lemongrass will be in an environment that more closely matches its native territory.
- Florida, southern California, and southern Texas fall within these zones.
- Knowing what USDA zone you live in and planting your lemongrass according to it will prevent your plant from dying from the cold.
- The chart below will guide you on the best time to plant lemongrass.
- However, it’s essential to watch the news and use common sense—if it sounds like a late frost could be in store, it’s best to wait for the threat to pass before planting.
|USDA Zone||When to Plant Lemongrass Outside|
|3a – 4b||Around May 15th (Annual)|
|5a – 7b||Around April 15th (Annual)|
|8a – 8b||Around March 15th (Annual)|
|9a – 9b||Around February 15th (Annual)|
|10a – 10b||December 1st – March 1st (Perennial)|
|11a – 11b||October 1st – March 1st (Perennial)|
Also, read: Growing Lemongrass in Pots
2. Lack of Nutrients
- Lemongrass is vulnerable if it isn’t in a tropical environment. So, it’s vital to ensure your lemongrass has access to an ideal level of nutrients to prevent it from dying.
- Some of the key nutrients that lemongrass needs include:
- Trace nutrients
You should also ensure your soil has a pH of 6.5 to 7.0.
- You should aim to fertilize your lemongrass with a product high in nitrogen every two to four months during the growing season. The fertilizer should also contain phosphorus.
- Nitrogen regulates lemongrass growth and development. So, a nitrogen deficiency is one of the most common reasons why these plants die.
- Your lemongrass can get trace nutrients from manure tea, a compost you can make at home by steeping aged manure in water.
Check: Why Are My Lemongrass Leaves Wilting? [How to Care]
3. Wrong Amount of Sunlight
- Lemongrass is a sun-loving plant. It relies on sunlight for photosynthesis, which helps it turn oxygen and light into carbohydrates for energy.
- Once it depletes its energy reserves and the plant has little to no access to a sufficient amount of sun to restore the reserves, your lemongrass will die.
- If your lemongrass is getting under six hours of direct sunlight per day, replant it in an area where it’ll receive more sunlight. You can also bring your plant inside and use artificial light.
- Cloudier climates aren’t necessarily a death sentence for lemongrass; this plant can grow with only three to five hours of sunlight, but it’ll be at a slower pace.
Check out: How to grow Lemongrass From Cuttings
4. Not Enough Water
- In its natural habitat, lemongrass has access to abundant water from rain and humidity.
- So, if you live with little rainfall, your lemongrass might be dying from dehydration. The problem compounds if lemongrass is growing in a hot, dry climate, such as Arizona.
- In that case, your lemongrass will suffer from a lack of natural rainwater and water evaporating from the soil.
- It’s best to water your lemongrass every one to two days to prevent it from dying, assuming it hasn’t rained. Using a spray bottle to mist your lemongrass’ leaves can also help revive it.
- If you live in a dry climate, you should also place mulch around your lemongrass. That way, it’ll help the soil retain moisture, slowing the evaporation rate and keeping the roots moist.
Read: How To Grow Lemongrass From Seed Indoors
5. Poor Drainage
- Although keeping your lemongrass well-watered is crucial to prevent it from dying, water can also kill your plant if it doesn’t have the proper drainage.
- There are many reasons why poor drainage is detrimental to lemongrass, including:
- Causes root rot
- Decreases soil aeration
- Prevents nutrient loss
- Reduces soil erosion
- If you plant your lemongrass in a low-lying area that collects a lot of water, transplanting it to higher ground can help improve drainage.
- If your lemongrass is in a higher elevation area, mixing free raining potting soil into the dirt can help improve drainage.
- Homemade compost is also effective for improving drainage and overall soil quality.
- Sometimes the fix to a dying lemongrass plant is as easy as ensuring a potted container has holes in it. Make sure the holes hover above the ground so that the water has an exit.
Check: What to Plant With Lemongrass
6. Small Space
- A single lemongrass plant requires at least five gallons of soil to thrive.
- Therefore, some people accidentally kill their lemongrass plants by constricting the space they have to grow.
- The situation worsens if you plant lemongrass plants too close together, as the roots compete for soil space.
- Lemongrass requires a minimum of five gallons of soil per plant. So, dying lemongrass from a lack of space is common in potted plants.
- If you suspect your lemongrass is dying from its roots not having enough space, transplant it into a larger pot with more soil.
- Should you have lemongrass growing in the ground, check the spacing of the plants. Lemongrass can grow as much as three feet wide and six feet tall.
- Therefore, you should space each lemongrass bulb at least three feet apart.
Read: How to Care For a Lemongrass Plant [Useful Tips]
7. Aphid Infestation
- Aphids can be as damaging as they sound—these ⅛-inch-long insects use their needle-like mouths to eat the sap from your lemongrass.
- Although the occasional aphid won’t kill lemongrass, these insects produce rapidly and can cause a slow but steady death for your plant.
- Some of the signs of a severe aphid infestation in lemongrass include:
- Yellowing leaves
- Dead shoots
- Stunted growth
- Curling leaves
- Pull out your magnifying glass, for you’ll be able to see if aphids are the reason your lemongrass plant is dying. These insects come in many colors, including red, yellow, green, and brown.
- You also might be able to see the white skins they leave behind on lemongrass leaves.
- Insecticides are the best way to have the highest chance of permanently getting rid of aphids.
- But if you prefer a more environmentally friendly approach, setting your hose on high and spraying your lemongrass leaves is also effective for killing them.
Check this post: How Do You Keep the Lemongrass Plant Healthy?
8. Mealybug Presence
- Mealybugs look like they’re from outer space, with a white or grey cotton wax appearance and a segmented body.
- Unfortunately for lemongrass, mealybugs thrive on grassy plants, eating nearly every part, including their roots.
- Signs that your lemongrass has a mealybug infestation include:
- Stunted growth
- Leaf dropping
- Chlorosis is the discoloration of the leaves. It can happen when too much of the mealybug’s sticky waste prevents sunlight from reaching a lemongrass’ leaves, preventing photosynthesis.
- Using two or three insecticide treatments that are 10 to 14 days apart is the most effective way to get rid of mealybugs.
- Non-chemical approaches are more challenging since mealybugs often return.
- However, you can try to throw away your infected lemongrass plant and clean up the soil around it before planting new lemongrass.
Read: Is Lemongrass Safe for Dogs? Can Dogs Eat Lemongrass?
9. Leaf Blight
- We’re now moving into fungal infections that can cause lemongrass plants to die, as leaf blight results from the fungus Helminthosporium turcicum.
- Unfortunately, leaf blight loves humid conditions, the kind of weather where lemongrass thrives.
- Leaf blight typically causes a lemongrass plant’s leaves to turn a deep reddish brown. The discoloration is most notable on the tips of the leaves and edges. The leaves also become dry.
- The best way to get rid of leaf blight is to treat your lemongrass with a fungicide.
- You should also prune the most infected leaves. Watering your lemongrass at the roots instead of spraying its leaves is also helpful, as leaf blight enjoys moisture.
- Leaf blight is highly contagious. So, if other plants around your lemongrass aren’t yet affected, it’s best to isolate your lemongrass to prevent the fungus from spreading.
Check: Are Coffee Grounds Good for Lemongrass?
10. Leaf Rust
- Leaf rust is another fungus that loves the wet, humid conditions that lemongrass requires for optimal health.
- The silver lining is that it rarely kills lemongrass, but it makes it appear unhealthy and the leaves won’t be appetizing to eat or use in tea.
- Tell-tale signs of leaf rust are:
- Distorted leaf shape
- Yellow or white spots
- Reddish-orange blisters
- Orange and yellow streaks
- Unfortunately, leaf rust is a fast spreader, using wind and water to transfer its spores from affected plants. So, if you keep your lemongrass outdoors, controlling leaf rust is challenging.
- Sometimes, the best fix for leaf rust is to grow a new lemongrass plant and keep it inside where it’s unlikely that it’ll have access to the fungus’ spores.
- If you keep your lemongrass plant outside, regular applications of botanical fungicide can help control the problem. You can also try dusting your lemongrass in sulfur once per week.
- Other strategies for keeping leaf rust in check include watering your lemongrass at the base of the plant and carefully removing its most infected leaves.
Also, Read: Why Is My Lemongrass Turning Purple? [Reasons & How to Fix]
11. Red Leaf Spot
- Helminthosporium fungus or Red leaf spot transfers between plants through relatively large, cigar-like spores.
- At first, it can be difficult to tell red leaf spots from leaf rust to the untrained eye, for the signs are similar.
- But as red leaf spot takes a stronger hold on your lemongrass plant, it can cause the leaves to collapse to the ground.
- Signs of red leaf spots include:
- Red to reddish-brown spots
- Irregular red patches
- Tan center in the red spots
- Blighted leaves
- Red leaf spots often start as small spots. As it progresses, the spots expand and merge into each other, forming irregular patches.
- Red leaf spot can kill your lemongrass plant, so it’s critical to act immediately. Using a fungicide every 14 to 21 days is an effective way to kill and control this fungus in the future.
- You should also take care not to give your lemongrass too much nitrogen, as red leaf spot thrives on it.
- As with any fungus infection, watering your plant at the base and avoiding its leaves is helpful.
- If you’re a truly dedicated lemongrass owner, it’s beneficial to remove morning dew on outdoor plants. That way, it removes moisture where the red leaf spot spores like to live.
Read: Is Lemongrass a Perennial?
When Dying Lemongrass Is Normal
- There’s a phenomenon called winter leaf die back in lemongrass. It occurs in USDA zones under nine, where frost or colder weather is present.
- During these cooler times of the year, the leafy part of lemongrass turns brown, shrivels, and appears to die. However, in many cases, the lemongrass bulb remains healthy beneath the soil.
- So, when cold weather strikes and you notice your lemongrass appearing to die, it’s best to leave it in place. Its wilted leaves will help protect the bulb from frost.
- Once spring rolls around and you’re sure there aren’t any more frosts in the forecast, it’s safe to cut away the lemongrass’ old leaves.
- With any luck, your lemongrass will soon start growing new leaves, and you’ll have another season to enjoy it.
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The Bottom Line
There are many insects, fungi, and environmental conditions that can kill lemongrass. Compounding the issue is that lemongrass doesn’t naturally grow in most parts of the U.S. Nevertheless, it’s often possible to cure a dying lemongrass plant.
By using the information we shared here, your plant will soon have a new lease on life.
I’m Elsa, and I love gardening. I started GardeningElsa.com as a resource for other gardeners, and I offer expert advice on gardening topics such as plants, flowers, herbs, and vegetable gardening. On my website, I share my latest tips and tricks for creating beautiful gardens. When I’m not working on my website, you can find me in my own garden, tending to my plants and flowers. Read more about me.