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Plant care

Kale (cavolo nero) care

Brassica oleracea var. sabellica

Also called curly kale, Tuscan kale, cavolo nero, Lacinato kale.

RHS H6USDA 3-9Mildly toxic to petsIndoor 60-90 cm tall

Watering rhythm

Direct sun (at least 4-6 hours)

2-3 cm per week

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Light

Direct sun (at least 4-6 hours)

Soil

Rich, well-drained loam

Humidity

40-70% (outdoor)

Temp

7-24°C

Pet safety

Mildly toxic to pets

Mature size

60-90 cm tall

Care at a glance

Light

Aim for at least 4-6 hours of direct sun on the leaves. Full sun to part shade. If your only bright window faces south, that's perfect for kale — same window any aroid would fry on.

Watering

Crops like kale reward consistent watering — 2-3 cm per week. The mistake is the daily light sprinkle: it never reaches the deeper roots. A long soak twice a week beats a five-minute splash every day. Consistent moisture keeps leaves tender; mulch to even out soil temperature.

Soil and pot

Kale grows best in rich, well-drained loam. Compost-rich; pH 6.5-7.5. Lime acidic soils to deter clubroot. A pot with a working drainage hole is non-negotiable for this species — even free-draining mix will turn soggy in a closed planter. If you love the look of a decorative pot without a hole, use it as a cachepot around an inner nursery pot you can lift out to water.

Humidity and temperature

Kale sits happiest at around 40-70% (outdoor) humidity and 7-24°C (45-75°F). Outdoor humidity rarely matters. If you keep the room above 7 year-round and avoid placing the plant near a cold draught, a hot radiator, or an air-conditioning vent, you have already handled the two biggest indoor stressors.

Fertilising

Feed kale sparingly. A balanced feed at planting; top-dress with nitrogen every 6 weeks during heavy harvesting. Skip fertiliser entirely on a stressed, recently-repotted, or actively wilting plant — fertiliser salts make damage worse, not better. Wait for a round of healthy new growth before resuming a feeding rhythm.

Common problems

Below are the issues we see most often on kale in the Growli community. Where a problem matches one of our diagnostic guides, click through for the full step-by-step recovery plan written for kale specifically.

  • Cabbage white caterpillars — Cover with insect mesh from early summer.
  • Aphids in leaf folds — Rinse off with water; encourage ladybirds.
  • Clubroot — Wet acidic soils; lime and rotate, do not plant brassicas in the same spot for 5+ years.
  • Yellow lower leaves — Nitrogen depletion in mature plants; side-dress with compost.

Companion plants

Kale pairs well with Onion, Beetroot, Dill, and Nasturtium. These are species with similar light and water needs, so you can grow them in the same bed or container without conflict.

Propagation

Sow seed in modules in spring; transplant out at 4-6 weeks. Propagation is the cheapest, most satisfying way to expand a collection — and it doubles as insurance against losing a mature plant to an accident. Take a backup cutting once the parent is established and healthy.

Toxicity to pets

Kale is mildly toxic to pets. ASPCA lists Brassica species as toxic to cats, dogs, and especially horses in quantity. Small amounts of cooked kale are widely fed to dogs without issue; large raw amounts can cause GI upset and goitrogen issues over time. If you keep cats, dogs, or curious children in the house, weigh placement carefully — a high shelf or a hanging planter is enough for casual safety. For severe ingestion incidents, call your local vet and the ASPCA Animal Poison Control Center (in the US, 888-426-4435).

Pet-safety status is sourced from the ASPCA Toxic and Non-Toxic Plant List, which catalogues the most-asked-about plants for cats, dogs, and horses.

Kale care — frequently asked questions

What is the common name for Brassica oleracea var. sabellica?

Brassica oleracea var. sabellica is most commonly called Kale, but it is also known as curly kale, Tuscan kale, cavolo nero, Lacinato kale. The names refer to the same species, so care instructions for Kale apply identically to anything sold as cavolo nero.

How much light does kale need?

Kale grows best in direct sun (at least 4-6 hours). Full sun to part shade.

How often should I water kale?

Water kale 2-3 cm per week. Consistent moisture keeps leaves tender; mulch to even out soil temperature. The finger-test (or lifting the pot to feel its weight) beats a fixed weekly calendar because pot size, light, and season all change how fast the soil dries.

Is kale toxic to cats and dogs?

Kale is mildly toxic to pets. ASPCA lists Brassica species as toxic to cats, dogs, and especially horses in quantity. Small amounts of cooked kale are widely fed to dogs without issue; large raw amounts can cause GI upset and goitrogen issues over time.

What USDA hardiness zone does kale grow in?

Kale is rated for USDA zone 3-9 and RHS hardiness H6. Outside that range, grow it as a container plant that overwinters indoors before the first hard frost.

Kale deep-dive guides

Every aspect of kale care, each with its own calibrated guide:

Related guides

Kale is also known as curly kale, Tuscan kale, cavolo nero, and Lacinato kale.