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How to Grow Brussels Sprouts 'Long Island Improved'

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Brussels Sprouts 'Long Island Improved'

Brassica oleracea var. gemmifera

vegetable

A cold-hardy brassica that produces small, cabbage-like sprouts along a tall central stalk. 'Long Island Improved' is a classic heirloom variety known for uniform, tightly packed sprouts and excellent flavor that improves after frost. This productive cultivar has been a gardening staple since the early 20th century.

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Example Brussels Sprouts 'Long Island Improved' timeline · Pittsburgh, PA (Zone 6b)

  1. Plant Brussels Sprouts 'Long Island Improved'

    Around Apr 17

    Near Pittsburgh's average last spring frost.

  2. Tend & protect

    Late spring–summer

    Watering, feeding, and pest-watch reminders.

  3. Harvest Brussels Sprouts 'Long Island Improved'

    Around Jul 16

    ≈ 90 days after planting

Sample dates for Pittsburgh, PA. Sign up to get exact Brussels Sprouts 'Long Island Improved' dates for your own zip code.

Growing Conditions

☀️
Sun: Full sun, 6-8 hours daily
💧
Water: Consistent moisture; 1-1.5 inches per week. Keep soil evenly moist but not waterlogged. Water at soil level to prevent fungal disease.
📏
Spacing: 18 inches
📅
Days to maturity: 90-110 days
🌱
Planting depth: 0.25 inches for seeds; transplants at same depth they were growing

Soil

Type: Rich, well-draining loamy soil
pH: 6.0-7.5
Amendments:
Compost or well-rotted manure Balanced fertilizer (10-10-10) Lime if soil is acidic Mulch to retain moisture and regulate temperature

Growing Zones

Find your zone →

Zones 4-8; thrives in cool-season climates with frost exposure

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

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Growth Stages

1

Seedling

3-4 weeks

Small plants with 2-4 true leaves, emerging 7-10 days after planting. Seedlings are delicate and pale green.

Keep soil consistently moist. Provide 12-14 hours of light daily if growing indoors. Thin direct-seeded plants to spacing when 2-3 inches tall. Avoid waterlogging to prevent damping-off.

2

Vegetative Growth

6-8 weeks

Plant develops sturdy central stem and expanded leaves. Height reaches 18-24 inches. Foliage is deep green and robust.

Maintain consistent watering and fertilize every 2-3 weeks with balanced or nitrogen-rich fertilizer. Mulch around base. Remove any yellowed or diseased lower leaves. Monitor for pests weekly.

3

Sprout Formation

4-6 weeks

Small button-like sprouts begin forming in leaf axils along the stem, starting from the bottom. Sprouts are tight and compact.

Continue regular watering and feeding. Stop removing leaves unless heavily damaged. Maintain consistent soil moisture to ensure uniform sprout size. Remove any flowering side shoots.

4

Sprout Sizing & Maturation

3-4 weeks

Sprouts enlarge to marble to walnut size. Outer leaves may yellow naturally. Flavor intensifies, especially after frost exposure.

Reduce nitrogen fertilizer to encourage compact, tight sprouts. Continue consistent watering. Frost actually improves flavor by converting starches to sugars. Remove yellowed outer leaves as they fall.

5

Harvest

4-8 weeks of continuous harvesting

Sprouts are firm, compact, and 1-1.5 inches in diameter. Plant continues producing from bottom upward over several weeks.

Begin harvesting when sprouts reach desired size. Support stem firmly when twisting off sprouts. Harvest from bottom upward as sprouts mature. Continue watering and light feeding to extend harvest.

Companion Planting

Plan your garden →

Plant with:

Beets Celery Dill Garlic Marigold Nasturtium Onion Potato Thyme

Avoid planting near:

Broccoli Cabbage Cauliflower Kale Other brassicas Fennel Kohlrabi Strawberry Tomato

Common Pests

  • Row covers over young plants, handpick eggs/caterpillars, Bt (Bacillus thuringiensis) spray, companion planting with thyme or dill

  • Handpick, Bt spray every 7-10 days, neem oil, parasitic wasp recruitment with flowering plants

  • Row covers, kaolin clay spray, neem oil, diatomaceous earth, avoid overhead watering

  • Strong water spray, insecticidal soap, neem oil, reflective mulch, encourage beneficial insects

  • Rotate crops (3-4 year rotation), improve drainage, apply lime to raise pH, remove infected plants immediately

  • Row covers, Bt spray weekly, handpick, encourage parasitic wasps

Uses

🍳

Roasting & Sautéing

Culinary

Brussels sprouts are excellent roasted with olive oil and garlic, or sautéed as a vegetable side dish. Their slightly sweet, nutty flavor becomes richer when caramelized by heat. [source]

🍳

Raw Salads & Slaws

Culinary

Thinly shaved raw sprouts add a tender, slightly bitter crunch to salads and slaws. They pair well with light vinaigrettes, nuts, and dried fruit. [source]

💊

Nutritional & Anti-Cancer Properties

Medicinal

Brussels sprouts are rich in vitamin C, vitamin K, and glucosinolates—compounds studied for potential anti-cancer properties. Regular consumption supports immune function and bone health. [source]

🏠

Winter Storage & Preservation

Household

Brussels sprouts store exceptionally well in cool conditions (32-40°F) for 3-4 weeks or can be frozen for longer storage. They retain flavor and texture through winter months. [source]

🦋

Pollinator & Beneficial Insect Support

Wildlife

When bolting or flowering in spring, Brussels sprouts attract pollinators and provide nectar for beneficial insects. These plants support garden biodiversity. [source]

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

Harvest Tips

Begin harvesting when sprouts are 1-1.5 inches in diameter and firm. Gently twist and snap sprouts off the stem, working from bottom to top as they mature—lower sprouts mature first. After picking lower sprouts, remove yellowed outer leaves to improve air circulation. The plant will continue producing upward for 4-8 weeks. Flavor is best after a light frost, which converts starches to sugars. Continue harvesting until the stem becomes woody or spring arrives.

Fun Facts

  • 🌱 'Long Island Improved' dates to the early 1900s and was named for the productive Brussels sprout farms of Long Island, New York, which supplied New York City markets.
  • 🌱 Brussels sprouts taste noticeably sweeter after exposure to frost because cold triggers the conversion of starches into sugars as a natural antifreeze mechanism.
  • 🌱 A single Brussels sprout plant can produce 50-100+ sprouts over a season, making it one of the most productive vegetables per plant footprint in the garden.

Gardening Terms

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

Cultivar Full Sun Heirloom Mulch True Leaves
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