How to Grow Kale

Kale grows in every US state, tolerates more cold than nearly any other vegetable, and produces continuously for months when harvested correctly. The catch: most gardeners either plant it too late in spring (missing the sweet spot before heat arrives) or harvest it all at once instead of picking outer leaves regularly.

This guide covers the practical details — varieties, planting timing, spacing, pests, and harvest technique — that determine whether you get two months of kale or four.

Kale varieties worth growing in the US

Three main kale types dominate US home gardens, each with distinct uses and characteristics.

For Zones 2–4 where winter temperatures drop severely, Siberian kale is the most reliable. For the best flavor in cooking, Lacinato consistently outperforms curly types in taste tests. For tender salad greens, Red Russian is a top choice — its leaves are less tough and much better raw.

When to plant kale in the US

Kale grows in cool weather (45°F–75°F). Heat above 80°F causes bolting and bitter leaves. Time plantings around this window.

Spring planting: Transplant or direct seed 4–6 weeks before your last spring frost date. Kale tolerates light frost (28°F–32°F), so early planting works. In Zone 5, this means planting in late March or early April for a May–June harvest.

Fall planting: This is kale’s best season. Plant 6–8 weeks before your first fall frost date so plants reach maturity as temperatures cool. Fall-grown kale improves dramatically after the first frost.

In Zones 9–11, kale is exclusively a cool-season winter crop. Summer temperatures are too high for quality production.

How to plant kale

Direct seeding (recommended for most US gardens)

Direct seeding is faster and cheaper than buying transplants. Kale seeds germinate reliably in 5–7 days at soil temperatures of 60°F–70°F.

1. Prepare a bed with 2 inches of compost worked into the top 8 inches.
2. Sow seeds ½ inch deep, spacing them 1 inch apart in rows.
3. Water the bed gently and keep soil moist until germination.
4. Thin seedlings to 12–18 inches apart once they reach 2–3 inches tall.
5. Use the thinnings as baby kale — they’re tender and excellent in salads.

For soil preparation guidance, see how to start a vegetable garden for complete bed setup steps.

Starting transplants indoors

Start transplants 5–6 weeks before your planned outdoor planting date. Use seed-starting mix, not potting soil. See how to start seeds indoors for the full setup.

Transplants let you get a head start in Zones 3–5 where the spring window is short. For fall crops, transplants provide better control of timing — you start them indoors during the hottest summer weeks when direct-seeding outdoors is unreliable.

Spacing

Plant kale 12–18 inches apart in rows 18–24 inches apart. Closer spacing (12 inches) works in raised beds. In-ground rows need 18 inches between plants.

Crowded kale has reduced air circulation and produces more aphid and fungal disease problems. Proper spacing also allows the plant to reach full size — mature kale plants can span 2–3 feet across.

Soil and fertilizing

Kale thrives in rich, well-draining soil at pH 6.0–7.5. It is a moderate feeder — less demanding than broccoli or cabbage but more nutrient-hungry than beans or carrots.

At planting: Work 2–3 inches of compost into the top 8 inches of soil. Add a balanced fertilizer (10-10-10) at the label rate if your soil hasn’t been amended recently.

Side-dressing: 3–4 weeks after transplanting or thinning, side-dress with a nitrogen fertilizer (fish emulsion, blood meal, or granular balanced fertilizer). Apply 6 inches from the stem. Kale growing in hot weather without adequate nitrogen turns yellow-green and stops producing.

Ongoing: Continue side-dressing every 4–6 weeks for plants that produce for multiple months.

See how to test soil pH to confirm your soil is in the right range before planting.

Watering

Kale needs 1–1.5 inches of water per week from rain plus irrigation. Consistent moisture prevents bitter leaves and premature bolting.

Mulch with 2–3 inches of straw or wood chips to retain moisture and keep roots cool during spring warm spells. See best mulch for vegetable garden for material comparisons.

In fall, reduce watering as temperatures cool — plants need less water and roots need good drainage to survive winter in Zones 5–7.

Pests and problems

Cabbage worms

Cabbage worms (larvae of the white cabbage butterfly) and imported cabbageworm loopers are the top kale pests across the US. They eat irregular holes in leaves, and heavy infestations strip plants to stems within days.

Best control: Install row cover fabric at seeding or transplanting. The fabric blocks adult moths from landing and laying eggs. It’s the most effective control available. Check under leaves weekly and hand-pick any caterpillars you find.

Organic spray: Bacillus thuringiensis (Bt) is a naturally occurring bacteria that kills cabbage worms specifically. Apply every 5–7 days on affected plants. It is safe for beneficial insects and people. For more on pest identification and organic control, see aphids and companion planting strategies.

Aphids

Cabbage aphids — gray-green, dusty-looking clusters — attack kale stems and undersides of leaves. They multiply rapidly in warm weather.

A strong spray of water from a hose removes most aphid colonies. Repeat every 2–3 days until the population drops. Neem oil spray controls moderate infestations. Row cover installed before infestation starts is the best prevention.

Harlequin bugs

In the South and Southwest (Zones 7–10), harlequin bugs (black with red/orange markings) can devastate kale. They inject toxic saliva that wilts leaves rapidly. Hand-pick adults and egg masses (barrel-shaped, white with black stripes, found on leaf undersides). No chemical control is highly effective; physical removal and row cover are the best options.

Harvesting kale for continuous production

The harvest method determines whether you get 6 weeks or 6 months of kale from the same plants.

How to harvest: Remove outer leaves (lowest on the stem) when they reach 4–8 inches long. Snap or cut the leaf stem where it meets the main stem. Never remove the central growing point (the top cluster of young leaves) — this is where new growth originates.

How much to take: Remove no more than one-third of a plant’s leaves at any harvest. Over-harvesting weakens the plant and slows regrowth.

Harvest frequency: In cool weather, harvest every 7–10 days. In warm weather (spring bolting risk), harvest more aggressively every 5–7 days to slow flowering.

Sign to harvest immediately: When the stem begins to elongate and form flower buds (bolting), harvest all remaining leaves at once. Bolted leaves become tough and bitter quickly. Remove the plant after bolting to make room for the next crop.

Companion planting for kale

Kale performs well alongside certain garden neighbors. See kale companion plants for a detailed look at what to plant near kale and what to avoid.

Good companions:

• Dill and fennel attract parasitic wasps that target cabbage worms
• Nasturtiums act as a trap crop for aphids
• Lettuce and other cool-season crops share the same timing and growing conditions
• Spinach pairs well — both are cool-season leafy greens that can be harvested together

Poor companions:

• Other brassicas (broccoli, cabbage, cauliflower) — share pests and diseases; plant together in the same rotation block but not directly adjacent

Growing kale through winter in Zones 5–8

Kale is one of the most cold-hardy vegetables available. In Zones 5–8, established plants survive hard freezes if given basic protection.

Cold protection strategies:

• Mulching: Apply 4–6 inches of straw mulch around plant bases after first frost. Mulch insulates roots, not leaves — the leaves themselves survive most freezes.
• Row cover: Lightweight floating row cover (1.5 oz per square yard) adds 4–6°F of frost protection. It’s enough to push harvests 3–4 weeks later into fall and winter.
• Cold frames: A simple cold frame (bottomless box with a glass or plastic top) lets kale grow through Zone 5–6 winters in most years.

After a hard freeze, kale leaves wilt and look dead. Give them 24–48 hours — most kale recovers fully once temperatures rise above freezing. This freeze-thaw cycle is what converts starches to sugar, creating the sweetness fall kale is known for.

Kale yield expectations

A single 10-foot fall row of kale — planted in late August in Zone 6 and harvested through November — provides more than enough for fresh eating, cooking, and a few batches of kale chips for a family of four. For larger preservation goals, plan on two 10-foot rows.