Brassica oleracea 'Long Island Improved', Long Island Improved Brussels Sprouts
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Vegetables

Brassica oleracea 'Long Island Improved'

Long Island Improved Brussels Sprouts

BrassicaceaeMediterranean

At a Glance

Typevegetable
Habitupright
Foliagedeciduous
Height24-30 inches
Width18-24 inches

Growing Zones

USDA Hardiness Zones

3a - 9b
Zone 3a
Zone 3b
Zone 4a
Zone 4b
Zone 5a
Zone 5b
Zone 6a
Zone 6b
Zone 7a
Zone 7b
Zone 8a
Zone 8b
Zone 9a
Zone 9b
These zones indicate the coldest temperatures this plant can typically survive.
Frost Tolerancehardy

Overview

Brassica oleracea 'Long Island Improved' is a cool-season vegetable cultivar that produces compact, firm sprouts along a sturdy central stem. This improved selection forms tight, round to oval sprouts approximately 1-2 inches in diameter that develop progressively from the bottom of the plant upward. The plant itself grows 24-30 inches tall with large, blue-green outer leaves that help protect the developing sprouts. The sprouts are densely packed with crisp, pale green outer leaves that tightly wrap around the tender inner core. Brassica oleracea 'Long Island Improved' was specifically selected for its uniform sprout development, improved cold tolerance, and reliable production in northeastern growing conditions. The sprouts maintain their quality well on the plant and have excellent flavor when harvested at proper maturity.

Native Range

Brassica oleracea is native to the Mediterranean region and western Europe, where wild forms can still be found growing along coastal cliffs and rocky shores. The Brussels sprouts form was developed through centuries of selective breeding in Belgium, with the 'Long Island Improved' cultivar being further refined for North American growing conditions in the early 20th century.

Suggested Uses

Brassica oleracea 'Long Island Improved' is excellent for fall and winter vegetable gardens, providing fresh produce when many other crops have finished. Ideal for home vegetable gardens where space allows for the plant's substantial size and growing requirements. The harvested sprouts are perfect for roasting, steaming, or incorporating into holiday meals and cold-weather dishes. This cultivar works well in succession plantings for extended harvest periods and is suitable for small-scale market gardening due to its reliable production and storage quality.

How to Identify

Brassica oleracea 'Long Island Improved' can be identified by its distinctive growth pattern of small, cabbage-like sprouts that form along a tall, thick central stem. The sprouts develop in the leaf axils between the large, blue-green outer leaves and the main stem. Unlike other brassicas, the sprouts are clearly visible as individual mini-cabbages ranging from marble-size when young to golf ball-size at maturity. The plant has a distinctive upright habit with leaves that can be removed to expose the sprout-covered stem, and the sprouts themselves are tightly formed with overlapping outer leaves in a spiral pattern.

Appearance

Size & Dimensions

Height2' - 2'6"
Width/Spread1'6" - 2'

Colors

Flower Colors

yellow

Foliage Colors

blue
green

Bloom Information

Bloom Period

J
F
M
A
M
J
J
A
S
O
N
D
Spring
spring of second year if overwintered

Detailed Descriptions

Flower Description

yellow (if allowed to bolt)

Foliage Description

blue-green to dark green outer leaves, pale green sprouts

Growing Conditions

Sun Requirements

Full Sun
• Full Sun: 6+ hours of direct sunlight
• Partial Shade: 3-6 hours of direct sunlight
• Full Shade: Less than 3 hours of direct sunlight

Soil Requirements

pH Range6.0 - 7.5(Neutral)
357912
Soil Types
loam
Drainage
well drained

Water & Climate

Water Needs

moderate to high

Frost Tolerance

hardy

Time to Maturity

3-4 months

Care & Maintenance

Care Guide

Brassica oleracea 'Long Island Improved' requires consistent moisture and fertile, well-draining soil rich in organic matter. Water deeply and regularly, providing about 1-1.5 inches per week, especially during sprout development. Side-dress with compost or balanced fertilizer mid-season when sprouts begin forming. Mulch around plants to retain moisture and suppress weeds. Remove lower leaves as they yellow to improve air circulation and focus energy on sprout development. The plant benefits from cool weather and light frosts, which actually improve flavor. Provide support if needed in windy areas due to the plant's top-heavy nature when mature.

Pruning

Brassica oleracea 'Long Island Improved' benefits from selective leaf removal during the growing season. Remove yellowing or damaged lower leaves regularly to improve air circulation and redirect energy to sprout production. About 3-4 weeks before anticipated harvest, remove the growing tip and upper leaves to encourage the remaining sprouts to mature uniformly. Harvest sprouts from bottom to top when they are firm and about 1-2 inches in diameter, twisting them off the stem. The plant can continue producing sprouts for several weeks with proper care.

Maintenance Level

moderate

⚠️ Toxicity Warning

Brassica oleracea 'Long Island Improved' is generally safe for human consumption when properly prepared and cooked. The sprouts and leaves are edible and nutritious. However, like other brassicas, the plant contains compounds called glucosinolates that can interfere with thyroid function if consumed in very large quantities over extended periods. The plant is generally considered safe for pets in small amounts, though large quantities may cause digestive upset. Raw sprouts may be difficult to digest for some individuals.

Planting Guide

Planting Methods & Timing

Planting Method

transplant

Indoor Start

6 weeks before last frost

Direct Sow Timing

early summer for fall harvest

Days to Maturity

90–110 days

Plant Spacing

24 inches

Companion Planting

Good Companions

carrots
onions
lettuce
spinach
beets
celery

Avoid Planting With

tomatoes
peppers
strawberries
pole beans
Brassica oleracea 'Long Island Improved' (Long Island Improved Brussels Sprouts) - Identification & Care Guide | PlantRef