Herb Leaves Turning Yellow? 8 Causes and How to Fix Them

You check on your basil, parsley or mint and notice a few yellow leaves. Don’t panic. In most cases, the plant is simply telling you that something in its care needs to change, and the fix is usually simple.

Herb leaves usually turn yellow because of one of these causes: overwatering (the most common), underwatering, too little light, a lack of nutrients, a pot that’s too small, cold drafts or pests.

To find yours, check three things: which leaves are yellow (the old lower ones or the new growth), how the soil feels (soggy or bone-dry) and where the pot sits. Fix the cause, remove the worst leaves and watch for new leaves coming in green.

In this guide, you’ll learn how to read the signs, use a quick diagnosis table and fix yellow leaves on each common kitchen herb.

Why do herb leaves turn yellow?

Leaves are green because of chlorophyll, the pigment plants use to turn light into food. When a plant is stressed, it makes less chlorophyll or shuts down its oldest leaves to save energy. The result is yellowing, also called chlorosis.

A yellow leaf isn’t the problem itself. It’s a symptom, like a fever. The real job is figuring out what’s causing it.

How do I find out what’s wrong?

Before changing anything, run through this quick check:

1. Look at which leaves are yellow. If it’s the lower, older leaves, the cause is usually too much water or a lack of nitrogen. If it’s the new growth at the tips, think iron deficiency or cold.
2. Do the finger test. Push a finger into the soil up to the second knuckle. Is it soggy, moist or dusty-dry?
3. Check the bottom of the pot. Does it have drainage holes? Does water drain out? Are roots poking through?
4. Look at the location. Does the pot get a few hours of direct sun? Is it near a cold window, an air conditioner or a heater vent?
5. Flip a leaf over. Look for tiny bugs, fine webbing or speckling on the undersides.

Yellow herb leaves: diagnosis table

What you see	Most likely cause	What to do
Lower leaves yellow and soft, soil always wet	Overwatering or poor drainage	Water less often, empty the saucer and check the drainage holes
Yellow, crispy leaves, wilting plant, dry soil	Underwatering	Water deeply until it drains out the bottom, then water more often
Whole plant pale green with thin, stretched stems	Not enough light	Move to your brightest window or add a grow light
Older leaves slowly yellowing, slow growth	Nutrient deficiency, usually nitrogen	Feed with compost, worm castings or a diluted liquid fertilizer
New leaves yellow with green veins	Iron deficiency or worn-out soil	Refresh the potting mix and feed with compost or castings
Roots coming out of the holes, soil dries out fast	Rootbound plant in a pot that’s too small	Repot into a slightly bigger container with fresh mix
Yellow speckles, fine webbing or tiny bugs under leaves	Pests such as spider mites or aphids	Rinse the leaves and spray with insecticidal soap
Yellow or dark leaves after a cold night	Cold, drafts or leaves touching cold glass	Keep away from drafts and pull leaves off the glass at night

Overwatering: the number one cause

Overwatering is the most common mistake with potted herbs. When soil stays soggy for days, roots can’t get oxygen. They start to rot and stop delivering water and nutrients to the plant. The classic sign is soft, yellow lower leaves with soil that never dries out and sometimes smells sour.

• Water only when the top inch of soil is dry.
• Empty the saucer about 15 minutes after watering.
• Use a pot with drainage holes and a light, well-draining potting mix, not garden soil.
• If the soil smells bad, slide the plant out, trim any brown, mushy roots and repot in fresh mix.

Underwatering

When herbs don’t get enough water, leaves turn yellow, get crispy at the edges and the plant wilts. The soil becomes hard and may pull away from the sides of the pot. This is common in small pots, hot sunny windows and dry, heated rooms in winter.

Water slowly until it runs out of the drainage holes. If the soil is so dry that water runs straight through, set the pot in a bowl of water for 15 minutes so it can soak it up from below. Then check the soil daily during hot weeks.

Not enough light

Without enough light, herbs can’t make enough food. They turn pale, grow thin, floppy stems and lean toward the window. Basil, rosemary and thyme suffer the most because they love direct sun.

Move the pot to your brightest spot. In the Northern Hemisphere, a south-facing window is best. If your herbs are already tall and thin, see our guide to leggy herbs and how to fix them. In winter, short days make this worse, so check out how to grow herbs in winter.

Nutrient deficiency

Herbs that you harvest often use a lot of nutrients to keep pushing out new leaves. Over time, potting mix runs out of food. A lack of nitrogen, the nutrient that drives leafy growth, yellows the older leaves first, from the bottom up.

During the growing season, feed every three to four weeks with a thin layer of compost or worm castings, or a liquid fertilizer at half strength. If you compost at home, learn how to use compost in pots. Don’t overdo it: too much fertilizer burns leaf tips and can also cause yellowing.

A pot that’s too small

When roots fill the whole pot, there’s little soil left to hold water and nutrients. The plant yellows, dries out quickly and stops growing. This happens a lot with grocery-store basil and mint, which are often several plants crammed into one tiny pot.

Move the plant into a pot one or two sizes larger with fresh potting mix. If it’s a clump of several plants, gently divide it into two or three pots.

Can too much fertilizer turn leaves yellow?

Yes. Many people see the first yellow leaf and reach for fertilizer, but overfeeding also damages roots. Fertilizer salts build up in the soil and burn the root tips, so they take up less water.

Common signs are brown, crispy leaf tips and edges, yellowing even when the soil is moist and a white crust on the soil surface or the rim of the pot. If the main problem is brown leaves rather than yellow ones, see our guide to herb leaves turning brown.

• Stop feeding for at least a month.
• Flush the soil: water slowly with plenty of water until it runs freely out of the drainage holes, to wash out excess salts. Let it drain completely and empty the saucer.
• Scrape off the white crust and add a thin layer of fresh potting mix.
• Resume feeding with less, at the label rate or even half of it.

Pests that cause yellow leaves

Some tiny insects suck sap from the leaves. The leaf loses strength and starts to yellow, usually in specks or patches. Because these pests hide on the undersides of leaves, many people don’t notice until the problem is serious.

• Spider mites: almost invisible. They leave fine yellow speckling, like grains of sand, and sometimes thin webbing. They love warm, dry indoor air, especially in winter.
• Aphids: small green or black insects that cluster on tips and new shoots. New leaves come in curled and yellowish.
• Mealybugs: look like small tufts of cotton on stems and under leaves.
• Whiteflies: a little cloud of tiny white flies that rises when you touch the plant.

How to treat pests on herbs

Start by rinsing the plant in the sink or shower to knock off as many pests as possible. Then spray the tops and undersides of the leaves with an insecticidal soap labeled for edible plants, following the directions on the bottle. Spray in the evening, out of direct sun.

Repeat every few days for two to three weeks, since eggs keep hatching. Test on one leaf first and wait a day to make sure the plant tolerates it. Always rinse leaves before eating them.

If tiny flies hover around the soil rather than the leaves, they’re likely fungus gnats, a sign the soil stays wet too long. The fix is the same as for flies in a compost bin: let the surface dry out between waterings.

Yellow leaves on specific herbs

• Basil: very sensitive to cold (below about 50°F) and soggy soil. If leaves yellow after flowering, pinch off the flowers so the plant goes back to making leaves. More in how to grow basil in a pot.
• Parsley: the outer, older stems yellow naturally, so always harvest from the outside in. Parsley is a biennial: in its second year it flowers and fades, and it’s time to replant. See how to grow parsley in a pot.
• Green onions: yellow tips usually mean thirst, hunger or old leaves. Cut them back to about 2 inches and they’ll regrow fresh. See how to grow green onions in a pot.
• Mint: likes moist but not soggy soil. It spreads fast, so it quickly becomes rootbound and needs a bigger pot or dividing. See how to grow mint in a pot.
• Rosemary: yellow or brown needles almost always mean too much water. Rosemary likes drier soil, a terracotta pot and lots of sun. Water only when the soil is dry an inch or two down.
• Thyme: similar to rosemary. It hates soggy soil and low light. If the center of the plant yellows, trim out dead stems so light and air can reach inside.
• Cilantro: yellows quickly once it bolts (starts to flower), especially in warm weather. At that point, the plant is finishing its life cycle. Harvest what you can and sow a new batch every three to four weeks.
• Oregano: tolerates dry spells well but not constantly wet soil. Lower leaves yellow when the pot is crowded or drains poorly.

Yellow leaves in summer vs. winter

The same yellow leaf can have different causes depending on the season.

In summer, underwatering is the usual suspect. Soil dries fast, especially in small pots and hot, west-facing windows. It’s also peak season for spider mites outdoors and for basil and cilantro bolting early.

In winter, it’s usually the opposite: too much water for a plant that’s barely growing. Add short days, cold glass and dry air from the heating, and the lower leaves start to yellow. See the seasonal care tips in how to grow herbs in winter.

Common mistakes when saving a yellowing herb

• Watering more “to help.” If the cause is overwatering, this makes it worse. Always do the finger test first.
• Fertilizing right away. A plant with damaged roots can’t use fertilizer. Fix watering and light first.
• Changing everything at once. Repotting, moving and changing your watering on the same day stresses the plant and hides what actually worked. Make one change at a time.
• Moving it into strong sun overnight. A plant used to shade can scorch. Increase light gradually over about a week.
• Giving up too soon. Yellow leaves won’t turn green again. New growth is the sign of recovery, and it takes a few days to show.

Should I cut off yellow leaves?

Yes, in most cases. A fully yellow leaf won’t turn green again, and removing it lets the plant put its energy into new growth. Fallen yellow leaves sitting on the soil can also invite mold and fungus gnats. Snip them off with clean scissors close to the stem.

If a lot of leaves are yellow, don’t strip them all at once. Fix the cause first, then remove them gradually as new leaves appear.

How to prevent yellow leaves on herbs

1. Use pots with drainage holes and a light potting mix.
2. Water only when the top inch is dry and empty the saucer.
3. Give herbs your brightest spot, or add a grow light.
4. Feed lightly every three to four weeks while they’re growing.
5. Repot when roots come out of the bottom.
6. Check under the leaves now and then to catch pests early.

To set up a healthy herb garden from the start, read our complete kitchen herb garden guide.

FAQ: yellow leaves on herbs