What to Do When Kale Looks Rough: Yellowing, Holes, or Curling Leaves

I walked out one morning to a patch of kale that looked like it had been through a storm — yellowing leaves drooped toward the soil, something had clearly been munching holes in the edges, and a few plants were curling in on themselves like they’d just given up.

If you’ve grown kale for more than a few weeks, you’ve probably seen it too. The good news? Most of it’s fixable. You don’t need to rip it out and start over — you just need to know what’s causing the problem. That’s what we’re going to break down here, one leaf issue at a time.

1. Yellowing Leaves? Your Soil’s Telling You Something

When kale leaves go yellow, it’s usually a cry for help — and 9 times out of 10, the problem is in the soil.

What Causes It

• Nitrogen deficiency: Kale is a heavy feeder, especially on nitrogen. Yellowing starts at the bottom and moves up.

• Magnesium deficiency: Yellowing between the veins, while the veins stay green.

• Overwatering: Soggy roots can’t absorb nutrients.

• Poor drainage or compacted soil: Roots suffocate and can't do their job.

How to Fix It

• Side-dress with compost or diluted fish emulsion.

• Test your soil if problems persist — a simple home kit will do.

• Check for pooling water after rain. If it lingers, improve drainage by loosening the soil or creating raised rows.

• Cut back on watering until the soil just holds moisture — not mud.

Grandma’s Tip: “If your boots squish in the garden, the kale’s rootin’ in soup.”

2. Holes in the Leaves? You’re Hosting a Pest Buffet

Kale leaves with holes aren’t just unsightly — they’re a sign that someone’s been feeding on your plants while your back was turned. Identifying the pest is half the battle.

Top Offenders

PestDamage PatternHow to SpotFlea BeetlesTiny “shotgun” holes, especially on young leavesSmall, black, and jumpyCabbage WormsRagged, chewed holes and dark green poop trailsGreen caterpillars hiding on undersidesAphidsCurling, puckering, sticky residue (honeydew)Clusters near growing tips or leaf veins

How to Fix It

• Flea beetles: Use floating row covers early, and sprinkle wood ash or diatomaceous earth on leaves.

• Cabbage worms: Hand-pick and destroy. Spray weekly with BT (Bacillus thuringiensis).

• Aphids: Spray off with water or a mix of water + a drop of castile soap. Encourage ladybugs or plant dill and yarrow nearby.

Prevention Tips

• Row covers from day one

• Rotate crops to disrupt pest life cycles

• Companion planting: Nasturtiums attract pests away from kale. Garlic repels aphids.

3. Curling Leaves? That’s Kale Under Stress

Leaf curl often gets blamed on pests, but more often it’s environmental stress. Kale is hardy, but it still needs some babying through rough patches.

Common Causes

• Heat stress: Especially common in summer in Zones 7 and up

• Cold shock: Early spring planting or sudden fall frosts

• Wind exposure or crowded spacing: Both cause root or leaf stress

What to Do

• Thin plants to 12–18 inches apart to give room and airflow.

• Add mulch to stabilize soil temperature and moisture.

• Prune off the most curled or damaged leaves.

• Provide shade cloth during extreme heat spells.

4. When to Prune, Compost, or Replant

Sometimes the best move is just knowing what not to try saving.

Prune if:

• Only a few leaves are affected

• Plant has healthy new growth

Compost if:

• Leaves are yellow, wilted, and clearly beyond use

• Infested or covered in mildew

Replant if:

• Stems are thin, spindly, or floppy

• Roots are rotted (you’ll know when you pull one up)

• Pest damage is widespread

If it’s late summer, replanting isn’t a loss — it’s a second chance. In Zones 5–7, late-season kale often turns out sweeter after a touch of frost.

5. Kale Rescue Checklist (Save or Print This)

Here’s a quick breakdown for diagnosing rough-looking kale:

SymptomCauseFixYellowing from bottom upNitrogen deficiencyAdd compost or fish emulsionYellowing between veinsMagnesium deficiencyUse Epsom salts in waterRandom yellow spotsOverwatering or poor drainageAdjust watering, loosen soilTiny holesFlea beetlesRow covers, DE, ashLarge chewed holesCabbage wormsHand-pick, spray with BTCurling up, not chewedHeat or wind stressShade, mulch, pruneCurling with stickinessAphidsSoap spray, companion plants

Want the printable version?
Download the Kale Rescue Card [Lead Magnet CTA here].

6. What Not to Do

Let’s make sure you don’t accidentally make it worse:

• Don’t overfeed — especially not late in the season.

• Don’t crowd your kale — airflow prevents pests and mildew.

• Don’t ignore pests — they multiply fast.

• Don’t plant kale in the same spot every season.

7. Kale Problems by Season (Zones 4–7)

SeasonCommon IssuesEarly SpringCold stress, aphids, flea beetlesSummer HeatLeaf curl, cabbage worms, overwateringLate Summer/FallSoil fatigue, curling from drought, powdery mildew

Zone-specific tip:
In Zones 5 and 6, plant a fall kale crop around August for the sweetest harvest of the year.

Final Word: Ugly Kale Can Still Feed You

Kale isn’t always pretty. That’s part of what I like about it. It grows when other crops fade. It keeps giving after a frost. It can look half-dead and still bounce back with a little compost and care.

Grandma used to say: “Kale ain’t pretty, but it’s proud. Treat it right and it’ll feed you twice.”

So if yours is looking rough, don’t toss the trowel. Look closer, take action, and learn from what the garden is telling you.