OnMySill

Kale / Leaf Cabbage

Brassica oleracea var. sabellica

description

Kale is a cold-tolerant leafy vegetable that grows well in beds and containers.

benefits

  • Pet-friendly, non-toxic to animals
  • Edible
  • Suitable for containers

How to care for Kale

sunlight

Wild cabbage relatives grow on sunny coastal cliffs, so kale is happiest in an open, bright spot. Give it more sun in cool weather and a little relief from harsh heat.

Full sun

Ideal for sturdy plants and plentiful leaves. Aim for approximately 6 or more hours of direct sun daily, especially in spring, fall, and winter.

Part shade, tolerated in heat

In hot summers, morning sun with afternoon shade helps leaves stay tender and slows bolting. Too little light makes growth sparse and slow.

For container kale, move the pot to catch winter sun, then give it afternoon shade once hot weather arrives.

watering

Keep kale's soil evenly moist, especially while seedlings establish and new leaves are growing. Water deeply, then let the surface begin to dry rather than keeping the roots constantly wet.

Warm, bright weather

Check containers about every 2-4 days and beds about once a week if rain is scarce. Water when the top 1 inch of soil feels dry; small pots and hot, windy days may need water daily.

Cool or low-light weather

Growth slows in cool, dim conditions, so container kale may need water roughly every 5-10 days. Check below the surface before watering, and skip it if the root zone is still moist or rain has soaked the bed.

Lift a container before watering: noticeably lighter soil is a better cue than following a fixed schedule.
Use pots with drainage holes and empty saucers after watering. Soggy soil can damage kale's roots.

humidity

Preferred humidity

40-60%

Kale comes from cool, often moist coastal conditions, but it is adaptable. Average household or outdoor humidity is usually fine as long as the soil stays evenly moist and air can move around the leaves.

Acceptable range

30-70%

Very dry heated air can cause crisp leaf edges, slower growth, and tougher young leaves. In humid weather, give plants space and water the soil rather than wetting foliage to reduce fungal problems.

For container kale in dry conditions, mulch the soil and shelter pots from hot, drying wind rather than misting the leaves.
  • Water thoroughly when the top 2-3 cm of soil feels dry.
  • Use a light mulch to slow moisture loss.
  • Keep indoor plants away from radiators and ensure gentle airflow.

temperature

Best growing temperatures

10-21°C (50-70°F)

Warm-weather limit

Above 24°C (75°F)

Kale is a cool-season crop, so it grows sweetest and most steadily in mild weather. It tolerates light frost, but sustained heat above 24°C (75°F) can make leaves tougher and encourage flowering.

Place containers where roots stay cool, and give plants afternoon shade when temperatures regularly exceed 24°C (75°F).
Protect young plants from hard freezes below about -4°C (25°F), especially in containers where roots chill quickly.

nutrition

March - October

Feed kale while it is making new leaves, about every 2-3 weeks in containers with a balanced liquid vegetable fertilizer at half strength. In beds, compost at planting and one light midseason feeding is usually enough. Stop when growth slows in cold or very hot weather.

Nitrogen

Nitrogen supports the leafy harvest kale is grown for. Steady, moderate feeding keeps leaves productive without pushing soft, pest-prone growth.

Potassium

Potassium supports sturdy growth and helps kale cope with changing weather. A balanced vegetable fertilizer supplies it alongside nitrogen.

Feed onto already moist soil, then water lightly. Brown leaf edges or a white crust on the potting mix can mean fertilizer salts are building up.

soil

Fertile, moisture-retentive soil that still drains freely

Kale needs steady moisture and nutrients for tender leaves, but its roots suffer in compacted, waterlogged soil. Mix garden soil or potting mix with compost, then add perlite or coarse grit for extra air flow, especially in containers.

pH 6,0 - 7,0

This is slightly acidic to neutral, a range where kale can take up nutrients well. Use a quality vegetable or all-purpose potting mix, and add compost to improve poor soil. If your soil is very acidic, a small amount of garden lime can help.

Use a pot with drainage holes and at least 25 cm of soil depth so roots have room and excess water can escape.