Why Is My Basil Dying? 6 Reasons Indoor Basil Wilts (and How to Save It)

Indoor basil usually dies for one of six reasons: not enough light, a supermarket pot crammed with too many seedlings, cold, watering that's too much or too little, flowering, or pests. Basil is a summer plant from warm, sunny places, so a kitchen windowsill in November is a hard life for it. The good news is that basil grows fast, so a struggling plant can often be saved within a week or two. Here's how to work out what's wrong.

1. Not enough light

The most common cause. Basil needs at least 6 hours of bright light a day, ideally direct sun.

Signs: tall, thin, floppy stems, small pale leaves, big gaps between leaves.

Fix: move it to your sunniest window, usually south-facing. In winter, a cheap LED grow light 6 to 12 inches above the plant, on for 12 to 14 hours a day, makes a huge difference.

2. The supermarket pot is overcrowded

Supermarket basil pots contain dozens of seedlings crammed into a small pot. They're grown to look full for a few days, not to live long. Within a week or two they compete for water and light and start collapsing.

Fix: split it. Gently tip the plant out, tease the root ball into 3 or 4 clumps, and pot each into its own container with fresh potting mix. Water well. It looks sad for a day or two, then takes off.

3. Cold

Basil hates cold. Below about 50°F (10°C), leaves turn black or brown and droop. Cold draughts from a window at night, or leaves touching cold glass, do the same.

Fix: keep it somewhere above 60°F (15°C), away from cold glass at night and away from open doors.

4. Watering: too wet or too dry

• Too dry: the whole plant wilts dramatically, then perks up within an hour of watering. Basil in small pots dries out fast.
• Too wet: leaves yellow, stems go dark and soft at the base, and the soil stays soggy. Often with tiny flies (fungus gnats) around it.

Fix: water when the top of the soil feels dry, thoroughly, and empty the saucer. Make sure the pot has drainage holes. Our guide to overwatering vs underwatering shows how to tell, and how to get rid of fungus gnats covers the flies.

5. It's flowering

Once basil flowers, it puts its energy into seeds, the leaves get smaller and more bitter, and the plant starts to decline.

Fix: pinch off flower buds as soon as you see them. Better still, harvest so it never gets there (see below).

6. Pests

Indoor basil gets aphids (tiny green insects on new growth), spider mites (fine webbing, speckled leaves) and whitefly. Rinse the plant under the tap, check under the leaves, and see our guide to spider mites and mealybugs for the persistent ones.

How to harvest so basil keeps going

The way you pick basil decides whether it lasts a week or a whole season:

• Pinch the top of each stem, just above a pair of leaves, rather than pulling off big leaves from the bottom.
• Each pinch makes two new stems grow from that point, so the plant gets bushier.
• Harvest often, taking no more than a third of the plant at a time.

Can a dying basil plant be saved?

If the stems are still green and firm, yes. Trim off dead and black leaves, fix the light and watering, and split the pot if it's a supermarket one. If the stems are black and mushy at the base, it's rotted; take cuttings from any healthy tops (they root in a glass of water in a week or two) and start again.

Planted can look at a photo of your basil and tell you which of these is most likely the problem. And if you have pets, basil is safe for cats and dogs; see plants safe for cats and dogs.

Common questions

Why is my basil wilting?

Usually the soil has dried out, which is common in small pots. If it's wilting in wet soil, the roots may be rotting from overwatering or cold.

Why does supermarket basil die so fast?

The pot is crammed with dozens of seedlings that compete for water and light. Split it into 3 or 4 smaller pots and it will last much longer.

Why are my basil leaves turning black?

Usually cold damage, from temperatures below about 50°F or leaves touching a cold window. Overwatering can also cause dark, soft stems.

How much light does indoor basil need?

At least 6 hours of bright light a day. In winter most windows aren't enough, so a grow light helps a lot.