How to Grow Brassicas (Cabbage, Broccoli)

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Brassicas (Cabbage, Broccoli)

Brassica oleracea var. capitata (cabbage), Brassica oleracea var. italica (broccoli)

vegetable

Brassicas are cool-season cruciferous vegetables that include cabbage and broccoli, both belonging to the species Brassica oleracea. They are nutrient-dense crops rich in vitamins C and K, fiber, and cancer-fighting compounds called glucosinolates. These hardy plants prefer temperatures between 45-75°F and can tolerate light frosts.

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Example Brassicas (Cabbage, Broccoli) timeline · Pittsburgh, PA (Zone 6b)

  1. Plant Brassicas (Cabbage, Broccoli)

    Around Apr 17

    Near Pittsburgh's average last spring frost.

  2. Tend & protect

    Late spring–summer

    Watering, feeding, and pest-watch reminders.

  3. Harvest Brassicas (Cabbage, Broccoli)

    Around Jun 16

    ≈ 60 days after planting

Sample dates for Pittsburgh, PA. Sign up to get exact Brassicas (Cabbage, Broccoli) dates for your own zip code.

Growing Conditions

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Sun: Full sun, 6-8 hours daily; afternoon shade beneficial in hot climates (zones 8+)
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Water: Consistent moisture: 1-1.5 inches per week via drip irrigation or soaking. Keep soil evenly moist but not waterlogged. Water at soil level to prevent fungal diseases. Increase frequency during head formation and hot weather.
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Spacing: 18-24 inches apart for cabbage; 18-24 inches for broccoli (depends on variety size) inches
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Days to maturity: 60-100 days for broccoli; 70-120 days for cabbage (varies by variety)
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Planting depth: 0.5 inches for seeds; transplants at same depth as soil ball

Soil

Type: Well-draining, fertile loamy soil rich in organic matter
pH: 6.0-7.5
Amendments:
Compost or well-aged manure (2-3 inches worked in) Balanced NPK fertilizer (10-10-10 or similar) Bone meal for calcium (helps prevent blossom-end rot and splitting) Kelp or seaweed extract for trace minerals Lime if pH is below 6.0

Growing Zones

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Zones 3-9; can be grown year-round in mild climates (zones 8-10) with proper timing

2a 2b 3a 3b 4a 4b 5a 5b 6a 6b 7a 7b 8a 8b 9a 9b

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Growth Stages

1

Seedling (Days 1-14)

2 weeks

First true leaves emerge after cotyledons; plant develops 2-4 leaves. Very tender and vulnerable to pests.

Keep soil consistently moist. Maintain 65-75°F temperatures. Provide bright light (grow lights if indoors). Thin seedlings to prevent crowding. Begin light fertilizing at 10 days with half-strength liquid fertilizer.

2

Vegetative Growth (Days 14-35 for transplants, Days 30-50 for direct seed)

3-4 weeks

Rapid leaf and stem growth; plant develops 6-12 true leaves. Root system expands significantly. Plants are established and more resilient.

Maintain consistent watering and full sun exposure. Fertilize every 2-3 weeks with balanced fertilizer. Harden off transplants gradually before planting out. Watch for first signs of cabbage worms and flea beetles.

3

Pre-Heading/Head Formation (Days 35-70)

4-5 weeks

Leaves begin to curl inward (cabbage) or central head/crown forms (broccoli). Plant reaches mature size. Visible head or crown becomes prominent.

Increase nitrogen slightly if leaves appear yellowing. Water deeply and consistently—irregular watering causes splitting in cabbage and poor head quality in broccoli. Apply mulch to regulate soil temperature and moisture. Monitor closely for pests; this is peak feeding time for cabbage moths.

4

Head Maturation & Harvest Ready (Days 70-100+)

2-4 weeks

Heads become firm and compact (cabbage should feel solid when squeezed; broccoli heads are tight and dark green). Outer leaves may yellow naturally.

Reduce nitrogen to prevent excess leaf production. Maintain even moisture to prevent splitting or bolting. Check harvest readiness regularly. For broccoli, side shoots will develop after main head is cut if plant is healthy.

Companion Planting

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Plant with:

Avoid planting near:

Fennel Kohlrabi Pole beans Strawberries Tomatoes Other brassicas (same bed in consecutive seasons)

Common Pests

  • Floating row covers over seedlings; Bt (Bacillus thuringiensis) spray; hand-pick larvae; neem oil every 7-10 days; encourage parasitic wasps by planting dill and fennel nearby

  • Bt spray every 5-7 days; floating row covers; hand removal; spinosad organic insecticide

  • Floating row covers on young plants; kaolin clay spray; neem oil; reflective mulches; diatomaceous earth; ensure strong plant vigor through proper watering and fertilization

  • Bt spray; insecticidal soap; row covers; pyrethrin spray; remove affected leaves immediately

  • Strong water spray to dislodge; insecticidal soap; neem oil; encourage ladybugs and lacewings

  • Crop rotation (don't plant brassicas in same bed for 4+ years); maintain pH above 6.8; improve drainage; remove infected plants immediately; solarize soil if severe

  • Ensure good air circulation; sulfur spray; neem oil; avoid overhead watering; remove affected leaves

  • Use disease-free seed; remove infected leaves immediately; avoid overhead watering; practice strict crop rotation; sanitize tools

Uses

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Fresh cooking & raw preparations

Culinary

Both cabbage and broccoli are versatile in the kitchen—broccoli is excellent steamed, roasted, or raw in salads, while cabbage is classic in slaws, stir-fries, fermented sauerkraut, and soups. Their mild, slightly sweet flavor develops when cooked gently. [source]

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Cancer-fighting compounds

Medicinal

Brassicas are rich in glucosinolates, compounds that break down into isothiocyanates when chewed or cooked. Research suggests these compounds may have anti-cancer and anti-inflammatory properties, making brassicas among the most nutrient-dense vegetables. [source]

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Vitamin C and K supplementation

Medicinal

Both cabbage and broccoli are excellent sources of vitamins C and K, which support immune function, bone health, and blood clotting. A single serving of broccoli provides over 100% of daily vitamin K needs. [source]

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Fermentation for gut health

Household

Cabbage's naturally high fiber and juiciness make it ideal for lacto-fermentation into sauerkraut and kimchi, which support digestive health through beneficial probiotics. This ancient preservation method creates living foods that improve over weeks or months. [source]

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Pollinator and beneficial insect support

Wildlife

If broccoli or cabbage is allowed to bolt, the small yellow flowers attract bees, butterflies, and parasitic wasps that prey on pest insects. This makes brassicas valuable in integrated pest management systems. [source]

This is not medical advice. LizPlants is not a medical resource. Always consult a qualified healthcare professional before using plants medicinally.

Harvest Tips

Cabbage: Cut mature heads at the base with a sharp knife when they feel firm and compact (typically 70-120 days). Late-season varieties can tolerate light freezes and improve in sweetness. Leave roots in ground to encourage smaller secondary heads. Broccoli: Harvest main head (4-8 inches across) while buds are still tight and dark green, before they begin to yellow or open into flowers. Cut 5-6 inches of stalk below the head. This encourages development of side shoots that can be harvested for 3-4 weeks. Best harvested in early morning for peak tenderness. Both crops keep 2-3 weeks in the refrigerator.

Fun Facts

  • 🌱 Cabbage and broccoli are the same species (Brassica oleracea) as kale, cauliflower, and kohlrabi—they diverged through selective breeding over centuries. A 6,000-year-old ancestor plant from the Mediterranean coastline gave rise to all of these modern varieties.
  • 🌱 Broccoli only became popular in North America in the 1920s; Thomas Jefferson grew it in his Monticello garden in Virginia, but it wasn't mainstream until Italian immigrants brought their culinary traditions and seeds to the US.
  • 🌱 Brassicas were historically used as a natural pesticide themselves—crushed cabbage leaves were applied to fields to repel insects, and their sulfurous compounds were used in traditional medicine for respiratory health.

Gardening Terms

New to gardening? Learn about terms used in this guide:

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