Lemongrass Yellowing Leaves: Causes and How to Fix It
When lemongrass blades fade to yellow instead of vivid green, it's usually telling you it's hungry, cold, or short on light. Here are the likely causes, ranked, with how to tell them apart and fix each one.
Nutrient shortage (the usual culprit)
What's happening
Lemongrass is a hungry grass that needs steady nitrogen to keep its blades green. Without regular feeding — especially in a container, where nutrients wash out fast — the whole clump pales and yellows and new growth slows.
How to confirm
The plant hasn't been fed in weeks, it's in a pot or poor soil, and the yellowing is generalized across the clump rather than confined to a few old blades. Growth looks sluggish despite warmth and sun.
How to fix it
Feed with a balanced or nitrogen-rich liquid fertilizer, then continue every 2–4 weeks through the growing season. A topdressing of compost helps garden clumps. Color usually returns to new growth within a couple of weeks.
Prevent it
Feed regularly through spring and summer and refresh container soil or topdress with compost each season.
Too little light
What's happening
Grown in shade or a dim indoor spot, lemongrass can't photosynthesize enough to stay deep green, so blades turn pale and yellowish and the stalks grow thin and floppy.
How to confirm
The plant sits in partial shade or away from a bright window, the clump is sparse and leggy, and the color is washed-out and weak overall rather than spotty.
How to fix it
Move it into full sun — at least 6 hours a day outdoors, or a south window with a grow light directly overhead indoors. Transition a shade-grown plant gradually over a few days to avoid shock.
Prevent it
Always give lemongrass the brightest, hottest spot available; it can't thrive on less.
Cold stress
What's happening
This frost-tender tropical yellows and browns when temperatures drop. Below about 40°F growth stalls and blades discolor; a freeze yellows or kills the top growth outright.
How to confirm
Yellowing follows a cold snap or chilly nights, an indoor plant sits near a drafty cold window, and the damage appeared suddenly after the temperature fell.
How to fix it
Move potted plants to a warm, bright spot above 50°F and away from cold glass. Outdoors, cover clumps before frost; if the top dies back, cut it down and wait — established roots often resprout when warmth returns.
Prevent it
Bring pots indoors before the first frost and shelter garden clumps in cold snaps with a frost cloth.
Waterlogged, soggy roots
What's happening
Though it loves moisture, lemongrass yellows if its roots sit in stagnant, airless water — usually a pot without drainage or a heavy, compacted soil that never drains.
How to confirm
The soil stays wet for days, the pot may lack drainage holes, and lower blades yellow while the base feels mushy or smells sour.
How to fix it
Stop watering and let the soil drain and dry somewhat. Move the plant to a pot with drainage holes and looser, faster-draining soil, trimming any soft, rotted roots before replanting.
Prevent it
Use a draining container and a well-draining mix; keep the soil moist but never let the roots stand in stagnant water.
When to worry (and when not to)
An occasional yellow blade on the oldest outer ring is normal as the grass retires old growth — pull or trim it and move on. Worry when yellowing spreads across the whole clump, when it follows a freeze and the base feels mushy, or when new growth comes in pale and thin. Most yellowing lemongrass recovers quickly once it's fed, warm, and in full sun.