How to Grow Kale from Seed: Fall & Spring Planting Guide

By Paul Smith, pemdasgarden.com

Kale has a secret: it gets sweeter after frost. While the rest of the garden surrenders to autumn, kale stands tall in the cold — its leaves converting starches to sugars, turning a humble green into something almost candy-like. It's the vegetable that laughs at winter.

And it's one of the easiest, most rewarding crops you can grow from seed. Two planting windows — spring and fall — mean you can harvest kale nearly year-round in many climates. Here's everything you need to know.

WHY GROW KALE FROM SEED?

A packet of kale seeds costs less than a single grocery-store bunch — and grows dozens of plants that produce for months. Kale is a cut-and-come-again crop: harvest the outer leaves and the plant keeps growing from the center, giving you continuous harvests from one sowing.

It's also a nutritional powerhouse — packed with vitamins A, C, and K — and one of the most cold-hardy vegetables in existence. Some varieties survive well below freezing and keep producing through winter under simple row cover.

Our pick for classic curled kale: Vates Blue Scotch Curled kale seeds — a compact, blue-green, finely curled variety that's been a garden standard for generations. Browse all our greens in the vegetable seed collection.

Two Seasons, Two Strategies

Kale is a cool-season crop that bolts (flowers prematurely) in summer heat. The trick is timing it for the cool shoulders of the year:

Spring planting: Direct-sow 2–4 weeks before your last frost date. Kale seedlings tolerate light frost easily. You'll harvest through late spring and early summer, until heat arrives.

Fall planting (the main event): Sow 6–8 weeks before your first expected fall frost. Fall kale grows through cooling weather, sweetens with each frost, and in mild climates produces all winter. Many gardeners consider fall the superior kale season.

Succession sowing: Sow small batches every 2–3 weeks during each window for a continuous supply of tender young leaves.

Sowing: the Details

Depth: ¼ to ½ inch deep.

Spacing: Sow seeds 1 inch apart in rows, then thin seedlings to 12–18 inches apart. Kale needs room — crowded plants stay small and invite disease. (Eat the thinnings! Baby kale is delicious.)

Soil temperature: Kale germinates in soil from 45–75°F (7–24°C), emerging in 5–10 days. It's one of the few vegetables that germinates happily in cool spring soil.

Soil: Rich, well-drained soil with a pH of 6.0–7.5. Work 2–3 inches of compost into the bed before planting — kale is a heavy feeder.

Sun: Full sun is ideal, but kale tolerates partial shade — especially welcome in warmer regions where afternoon shade delays bolting.

Growing on: Feed the Leaves

Kale is grown for its leaves, and leaves want nitrogen. Side-dress with compost or a nitrogen-rich fertilizer 3–4 weeks after transplanting, and again mid-season for fall crops.

Water: About 1–1.5 inches per week. Consistent moisture keeps leaves tender; drought stress makes them tough and bitter.

Mulch: 2–3 inches of straw or shredded leaves conserves moisture, suppresses weeds, and keeps soil cool — kale appreciates all three.

The frost bonus: Don't rush to pull spring kale when summer heat hits, and definitely don't fear fall frosts. Light frosts (down to ~28°F) sweeten the leaves. Hardy varieties survive into the teens with row cover.

Pests and Problems

Kale's main enemies are the cabbage family pests:

Cabbage worms (those velvety green caterpillars) chew holes in leaves. Inspect leaf undersides for tiny yellow eggs; handpick caterpillars or spray Bt (Bacillus thuringiensis), an organic biological control.

Flea beetles pepper seedlings with tiny shot-holes. Floating row covers from day one are the best prevention — they block beetles while letting light and rain through.

Aphids cluster on new growth. Blast with water or introduce ladybugs.

Bolting: In heat, kale sends up a flower stalk and leaves turn bitter. Harvest promptly, or let it flower — the yellow blossoms feed pollinators, and you can save the seeds.

The single best investment for kale: floating row covers. They prevent most pest problems before they start.

Harvest: Cut and Come Again

Begin harvesting when leaves are about the size of your hand. Always pick the outer leaves first, leaving the central growing point intact — the plant continues producing new leaves from the center for months.

Harvest in the cool of the morning for the crispest leaves. A mature plant can be harvested weekly through its season.

Baby kale: For salads, harvest leaves at 2–3 inches. Sow thickly and cut the whole patch like microgreens.

Storage: Refrigerate unwashed leaves in a bag for up to a week. Kale also freezes beautifully — blanch 2 minutes, ice bath, squeeze dry, and freeze.

Winter harvest trick: In cold climates, bury fall kale under straw mulch or a low tunnel. Dig through snow for the sweetest kale of the year.

Companion Greens to Try

Kale loves company in the cool-season garden. Pair it with Astro arugula seeds for peppery salads and Mizuna mustard seeds for mild Asian greens — all three thrive in the same cool conditions and similar sowing windows.

Timing matters in the garden. Our gardening tools hub has a seed-starting date calculator and a frost date finder to help you plan sowing around your local climate.

Frequently Asked Questions

Why did my kale bolt?
Heat or day-length stress. Plant for fall harvest to avoid it, choose bolt-resistant varieties, and harvest promptly in warm spells.

How cold-hardy is kale really?
Very — mature plants typically survive down to 10–20°F, and sweeten with frost. Under row cover or in mild climates, harvest continues all winter.

Can I grow kale in containers?
Yes — one plant per 3–5 gallon pot. Dwarf varieties like Vates Blue Scotch Curled are ideal for containers.

My kale leaves are tough and bitter. What went wrong?
Usually heat or drought stress. Keep water consistent, mulch well, harvest young leaves, and wait for cool weather — fall kale is a different vegetable from stressed summer kale.

How long does one planting produce?
With cut-and-come-again harvesting, a spring planting gives 6–10 weeks; a fall planting can produce for months, even through winter in mild zones.

Timing varies by climate region — count backward from your frost dates to set sowing times. In frost-free climates, grow kale through the coolest months as a winter annual.

Wrapping Things Up!

Spring kale, fall kale, frost-sweetened winter kale — one packet of seeds, months of harvests, and a vegetable that gets better when the weather gets worse. That's hard to beat.

Start with our Vates Blue Scotch Curled kale seeds, explore the vegetable seed collection, and browse all our Growing Guides. Happy growing! 🥬