Vegetable · Brassicaceae
Kale
Brassica oleracea Acephala Group
Forgiving and generous, kale rewards a first-time grower with tender leaves from spring right through winter.
Full sun
Every 3–7 days
55–75 days
USDA 2–11
Overview
Kale belongs to the cabbage family, but instead of a tight head it forms a loose, open rosette of leaves you can pick from as they grow. You will find it in many looks, from the ruffled blue-green curls of the everyday types to the long, puckered straps of the Italian heirlooms. Best of all, it is among the most forgiving vegetables a beginner can plant, so early mistakes rarely cost you the crop.
At its heart this is a cool-season crop that feels most at home in the gentle weather of spring and fall, and it shrugs off frost that would finish a tomato overnight. The cold is actually your friend here, because a hard chill coaxes the leaves sweeter and milder rather than tougher, so a late-season plant tastes better than ever.
Give kale full sun, steady water, and rich soil, and a single planting keeps feeding you for months without fuss. You simply pick the outer leaves as you need them and let the center grow on, so the harvest stretches out gently instead of ending all at once and you always have more coming.
Care
The short version: give kale full sun and rich, evenly moist soil with about an inch to an inch and a half of water each week, and you are set. Feed it through the season, plant once for spring and again for fall, and simply pick the lower leaves as you need them.
Light
Kale is happiest in full sun, with at least 6 hours a day to fill out into a leafy plant. It will manage in partial shade too, which helps where summer heat runs strong, though deep shade leaves you with thin, slow plants and sparse leaves.
Water
Keep the soil evenly moist, aiming for about 1 to 1.5 inches of water a week. That steady moisture is the secret to tender, mild leaves rather than tough, bitter ones, so a comfy layer of mulch to hold the water in really pays off.
Soil
Set kale in fertile, well-drained loam enriched with plenty of organic matter. A pH of 6.0 to 7.5 suits it nicely, and nudging acidic soil toward the top of that range does double duty by helping hold clubroot at bay.
Temperature
This cool-season plant is content across a wide band of 10°F to 81°F (-12°C to 27°C). It takes hard frost in stride and even sweetens up in the cold, so you need not worry as winter nears, while real summer heat is what turns leaves bitter and pushes it to bolt.
Humidity
Kale asks for nothing special when it comes to humidity, so there is no target to chase. Good airflow matters far more, since crowded, damp leaves are what invite the aphids and diseases that trouble brassicas.
Feeding
Work a balanced fertilizer into the bed at planting, guided by a soil test, then side-dress with a little nitrogen about 4 to 6 weeks on to keep fresh leaves coming. Go easy on the nitrogen, though, or the soft, lush growth simply invites aphids.
Pruning
You will not need to prune kale in any real sense. Harvest the lower, outer leaves once they are large but still tender, leave the central growing point untouched so the plant keeps producing, and just pinch off any leaf that yellows or gets chewed.
Size & spacing
Plants grow to 1 to 3 feet (30 to 100 cm) tall and spread nearly as wide, so give them room. Setting them 12 to 18 inches (30 to 45 cm) apart lets air move freely between plants and gives each one space to fill out comfortably.
When to plant
Kale is made for cool weather and a long, easygoing season. Sow it in early spring for an early summer cutting, then sow again in midsummer for a fall and winter crop that only grows sweeter as the cold arrives, so you never have to rush.
Northern hemisphere
Southern hemisphere
Typical months for a temperate climate: start earlier in warm zones, later where spring frosts linger.
- Sow: Start seed indoors 6-8 weeks before the last spring frost; for a fall crop, start in mid-summer
- Plant: Set transplants out 3-4 weeks before the last spring frost, or direct sow as soon as soil is workable; sow again in mid- to late summer for fall harvest
- Harvest: Harvest spring sowings in late spring to early summer before heat turns leaves bitter; harvest fall crops into winter - flavor sweetens after light frosts
Hardiness
USDA hardiness zones: 2–11
Temperature: down to -46°C
Troubleshooting
Most kale troubles show up on the leaves, right where the chewing pests and sap-suckers work in plain view, so nothing hides for long. Peek under the leaves often and you will spot problems while they are small and easy to handle. Find your symptom below, then step in before it spreads.
Wilting, stunted plants with swollen roots
When a plant droops in the warm afternoon, yellows, and seems stuck, ease it out of the ground and take a look at the roots. Thick, club-shaped swellings mean clubroot, a soilborne disease that cannot be cured once it settles in, while tunneled roots holding small white grubs point instead to cabbage root maggot. Pull and destroy the affected plants rather than composting them, then give your brassicas fresh ground and lime the old bed toward pH 7.0 or above so the next crop starts clean.
Fix:
- Remove and destroy infected plants; do not compost them
- There is no cure in infested soil - grow brassicas elsewhere
Chewed leaves with ragged holes and green specks
If the leaves look nibbled and you spot green crumbs underneath, you are almost surely looking at cabbageworms and cabbage loopers, sometimes joined by diamondback moth larvae. Try not to worry, because plucking the caterpillars off by hand goes a long way, and a spray of Bt or spinosad handles the stubborn ones. Slipping a floating row cover over your plants at transplanting stops the moths from laying eggs, and that keeps you ahead of the whole cycle.
Fix:
- Handpick caterpillars
- Apply Bacillus thuringiensis (Bt) or spinosad according to label directions
Curled, sticky leaves crowded with little insects
Those waxy gray-green clusters tucked into the leaf folds are cabbage aphids, and they are far easier to clear than they look. A hard jet of water knocks most of them loose, and a follow-up with insecticidal soap on the undersides takes care of the rest. The good news is that lady beetles and parasitic wasps will patrol the next batch for you, so let them stay and do the work.
Fix:
- Dislodge with a strong spray of water
- Apply insecticidal soap, covering leaf undersides thoroughly
- Encourage natural enemies such as lady beetles and parasitic wasps
Small round pits scattered across young leaves
Those little round pits come from flea beetles, tiny black specks that hop off before your hand gets near. They mainly bother seedlings during warm, dry spring spells and hardly ever set a strong plant back, so take heart. Keep the young ones under row cover and growing quickly, and they will outrun the nibbling with room to spare.
Fix:
- Protect young plants with row cover
- Apply a labeled insecticide if damage is severe on seedlings
Toxicity
Kale is a food crop from top to bottom, safe for you and for the animals around the garden, so you can breathe easy. There is no toxin to fret over, and the only gentle note is moderation: very large amounts of the raw brassica foliage, fed day after day, can act as a mild goitrogen for grazing livestock.
Safe for
People · Cats · Dogs · Horses · Rabbits · Livestock · Birds
Cats None
You can relax if your cat samples a leaf, since kale holds no toxin for them. The worst a big mouthful of raw greens might bring on is a bit of gas or a soft stool, and that passes on its own.
Dogs None
Kale is a safe green for dogs and turns up in many home-cooked bowls, so there is nothing to fear. Just keep the servings small, because a sudden pile of raw leaves can leave a pup gassy or a little queasy.
Horses Safe
There is no poisoning risk in kale for horses, so a nibble is perfectly fine. Offer it now and then rather than daily, since a steady run of brassica greens can act as a mild goitrogen over time.
Rabbits Safe
Your rabbit can enjoy kale as one green among several in the bowl. Bring it in gradually and keep the portions modest so it never edges out the hay their gut depends on.
Livestock Safe
Cattle, goats, and sheep graze kale without harm, and growers plant it on purpose as forage. Day after day of nothing but the foliage can work as a goitrogen, so let it share the ration with other feed.
Birds Safe
Chickens and other birds love pecking at kale, leaves and stalk together. It gives them a wholesome green treat, and no part of it needs avoiding.
People Safe
Kale is a friendly everyday vegetable for the table, lovely raw in a salad or gently cooked. A quick rinse under the tap is all it needs, just as you would with any garden green.
Like other brassicas, kale contains goitrogenic compounds; very large quantities of raw kale fed routinely could affect thyroid function or cause digestive gas in pets and livestock - a moderation note, not a poisoning risk.
Varieties
Dozens of kale cultivars exist, yet a handful keep turning up in gardens and on extension lists for good reason. These are the friendly, dependable ones worth knowing by name as you start out.
Lacinato (Tuscan, Dinosaur)
This Italian heirloom carries narrow, dark blue-green strap-like leaves with deep puckering, and UF/IFAS singles it out as a good pick for Florida gardens.
Winterbor
A hybrid that stands up to hard cold, Winterbor grows tall and keeps producing, wearing finely curled blue-green leaves.
Redbor
With deep red-purple curly leaves that only richen as the weather cools, Redbor looks at home in a flower bed just as much as on the plate.
Red Russian
Among the sweetest kinds you can grow, Red Russian offers tender, flat, toothed gray-green leaves veined and stemmed in purple.
Vates Dwarf Blue Curled
A short, compact curly standard that holds off bolting, Vates Dwarf Blue Curled has been an extension favorite for years.
Companions
Kale grows best beside aromatic herbs and alliums that throw pests off the scent, and worst beside its brassica cousins, which trade the same diseases and pests back and forth.
Plant near
Dill: Aromatic herb whose flowers attract parasitic wasps and other beneficial insects that prey on cabbageworm and aphid pests of brassicas
Onion: Aromatic allium interplanted with brassicas may help confuse or deter common insect pests and competes little for space
Beet: Compatible cool-season root crop that occupies a different root zone and shares similar growing conditions without hosting brassica pests
Keep apart
Cabbage and other brassicas: Crops in the same family share pests and diseases (cabbageworms, aphids, clubroot, black rot); grouping them in the same bed and skipping rotation lets problems build up
Strawberry: Traditionally listed as a poor neighbor for brassicas; the perennial bed also conflicts with the crop rotation brassicas need
How to propagate
Kale is one of the kindest vegetables to start, sprouting readily from seed sown right in the ground or raised as easy transplants, so a first attempt rarely disappoints.
SeedEasy
Direct sow in early spring as soon as soil can be worked and again in mid- to late summer for a fall crop, or start indoors 6-8 weeks before the last spring frost · Seed germinates in about 5-10 days; transplants reach setting-out size in 4-6 weeks and plants mature in roughly 55-75 days
You will find kale wonderfully easy to raise, whether from seed sown right in the bed or grown on as transplants. Sow the first round in early spring the moment the soil can be worked, sow again in mid- to late summer for a fall crop, or get a head start indoors 6 to 8 weeks before the last frost. Tuck the seed 1/4 to 3/4 inch deep and give plants 12 to 18 inches of elbow room. The seedlings pop up in about 5 to 10 days, are ready to set out in 4 to 6 weeks, and mature in roughly 55 to 75 days.
Myths
Frost ruins kale, so the crop must be finished before cold weather sets in.
Take heart, because kale is one of the sturdiest vegetables you can plant, brushing off frost and light freezes that would flatten a tender crop. A cold snap even improves it, since the plant turns its starches to sugar and the leaves grow sweeter. Fall and winter are exactly when kale tastes its best.
You have to pull up the whole kale plant to harvest it.
There is no need to sacrifice the plant, so pick the big lower leaves and leave the central growing point be, and it will keep sending up fresh ones. A single plant can feed you for weeks or months of steady picking instead of one final cut.