What hardiness zones is Brassica oleracea 'Long Island Improved' suitable for?

Brassica oleracea 'Long Island Improved' is Long Island Improved Brussels sprouts, an annual vegetable reaching 20–24 inches (50–60 cm) tall and 18–24 inches (45–60 cm) wide with an upright single-stemmed compact habit — shorter and more compact than most Brussels sprout cultivars. The cultivar is an American heirloom developed on Long Island, New York, in the early 1900s. Plants produce firm round medium-green sprouts 1–1.5 inches (2.5–4 cm) in diameter along a stocky central stalk — typically 50–100 sprouts per plant. The compact stature suits smaller gardens and windy sites without staking. Maturity is 90–100 days from transplant, earlier than 'Diablo' at 110–120 days. The cultivar is open-pollinated and grows true to seed. Flavor improves after frost. Family Brassicaceae.

Native Range

The parent species Brassica oleracea (gemmifera group) is descended from wild cabbage native to coastal Europe. 'Long Island Improved' was developed on Long Island, New York, in the early 1900s.

Suggested Uses

Grown in vegetable gardens and containers of 5 gallons (19 L) or larger for culinary use in roasting, sautéing, and steaming. The compact short plant suits small gardens and windy sites without staking. Typical yield is 50–100 sprouts per plant. Open-pollinated seed supports home seed-saving. The 90–100 day maturity is faster than most Brussels sprout cultivars. Cool-season crop — not suitable for warm-winter regions where vernalization and cold-induced sweetness do not occur.

How to Identify

Identified by firm round medium-green sprouts 1–1.5 inches (2.5–4 cm) along a stocky central stalk 20–24 inches (50–60 cm) tall with 50–100 sprouts per plant. Separated from 'Diablo' by shorter more compact stature (20–24 versus 24–36 inches), faster maturity (90–100 versus 110–120 days), and open-pollinated (versus hybrid) breeding. Separated from head cabbage by the multiple small sprouts along a central stalk rather than a single terminal head.

Appearance

Size & Dimensions

Height1'8" - 2'

Width/Spread1'6" - 2'

Colors

Flower Colors

yellow

Foliage Colors

blue

Fall Foliage Colors

no change

Bloom Information

Grown as an annual for sprout harvest. Four-petaled yellow flowers open only if the crop is overwintered or vernalized. Harvest occurs before bolting; plants are started in spring for fall harvest.

Detailed Descriptions

Flower Description

Yellow; four-petaled; only if bolting

Foliage Description

Blue-green fan-shaped leaves above medium-green sprouts on a stocky central stalk

Growing Conditions

Sun Requirements

Full Sun

Requires 6-8 hours of direct sunlight daily

• 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

Drainagewell drained

Water & Climate

Water Needs

High

Frost Tolerance

hardy

Time to Maturity

90-100 days from transplant

Care & Maintenance

Care Guide

Seed is started indoors 10–12 weeks before the first fall frost date. Transplants are moved into rich moist well-drained soil at pH 6.0–7.5. Consistent moisture and heavy feeding support sprout development along the stalk. The compact stature removes the staking requirement of taller Brussels sprout cultivars in small gardens. Maturity is 90–100 days from transplant. The plant is topped (growing tip removed) 3–4 weeks before the final harvest to redirect energy into finishing the remaining sprouts. Harvest proceeds bottom-up as sprouts reach 1–1.5 inches (2.5–4 cm). Frost improves flavor.

Pruning

Lower yellowing leaves are removed as sprouts develop on the stalk. The growing tip is topped 3–4 weeks before final harvest to concentrate energy into sprout maturation. Harvest proceeds bottom-up from the base of the stalk upward.