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Brassica spp.

cabbages and mustards

Brassicaceae

Europe, Mediterranean, and temperate Asia

Attracts Pollinators Attracts Butterflies Container Friendly

SunFull Sun – Part Shade

WaterMedium

Overview

Brassica spp. is a genus of about 37 species of annual, biennial, and short-lived perennial herbs in the mustard family (Brassicaceae), native to western Europe, the Mediterranean, and temperate Asia. The genus contains many widely grown cool-season vegetables and oil crops, including cabbage, kale, broccoli, cauliflower, Brussels sprouts, and kohlrabi (all B. oleracea), turnip and many leaf greens (B. rapa), rapeseed and rutabaga (B. napus), and several mustards (B. juncea, B. nigra). Wild and cultivated plants range from low leafy rosettes to branched flowering stems 1-6 feet (30-180 cm) tall. Leaves vary from smooth and blue-green with a waxy bloom to crinkled, lobed, or deeply cut, and may form dense heads or open rosettes depending on the crop. The flowers have four petals arranged in a cross, usually bright yellow and sometimes white or pale, carried in elongating clusters, and are followed by slender seed pods called siliques 1-4 inches (2.5-10 cm) long. Most species grow fastest in cool weather and bolt to flower as temperatures rise or days lengthen. Several, including B. nigra and B. rapa, have naturalized as weeds of fields and roadsides across much of the world. Plants are killed or damaged by hard freezes, though many tolerate light frost.

Native Range

Brassica spp. species are native to western and southern Europe, the Mediterranean Basin, and temperate Asia, with a center of diversity around the Mediterranean. Through millennia of cultivation and escape, species such as B. rapa and B. nigra have naturalized across temperate regions worldwide.

Suggested Uses

Brassica spp. crops are grown in vegetable gardens, raised beds, and containers for leaves, heads, roots, stems, and seed oil, spaced 12-24 inches (30-60 cm) apart depending on the crop. Ornamental kales and cabbages are used in fall and winter bedding for their colored rosettes. Flowering and cover-crop types are grown as green manure and pollinator forage.

How to Identify

Recognized by four-petaled flowers in the shape of a cross, usually yellow, borne in lengthening clusters and followed by slender two-parted pods (siliques) with a beak at the tip. Foliage is often blue-green with a waxy coating and ranges from smooth to crinkled or deeply lobed, with a sharp, cabbage-like smell when crushed. Cultivated forms may produce dense heads, swollen stems, or thickened roots. The cross-shaped flower and elongated silique distinguish Brassica spp. from mustards in related genera such as Sinapis spp., which differ in pod and seed details.

Appearance

Size & Dimensions

Height1' - 6'

Width/Spread1' - 3'

Colors

Flower Colors

Foliage Colors

Fall Foliage Colors

Bloom Information

Bloom Period

~4 weeks

Spring Summer

Brassica spp. species flower mainly in spring and early summer, generally April to June, as overwintered or cool-grown plants bolt with rising temperatures and longer days. Biennial crops such as cabbage, turnip, and rutabaga flower in their second season. The yellow or white four-petaled flowers open in succession over two to four weeks.

Detailed Descriptions

Foliage Description

blue-green to green, some purple

Growing Conditions

Sun Requirements

SunFull Sun SunPartial Shade

Requires 6-12 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 clay silt

Drainagewell drained

Water & Climate

Water Needs

Medium

Care & Maintenance

Care Guide

Most species grow in full sun and fertile, moisture-retentive soil with a pH of 6.0 to 7.5; near-neutral soil also limits clubroot disease. Steady moisture and cool temperatures produce the fastest leafy growth, while heat, drought, and crowding trigger early bolting and bitter flavor in vegetable crops. Plants are heavy feeders that respond to nitrogen-rich soil and regular watering. Common problems include cabbage white caterpillars, aphids, flea beetles, and the soil-borne disease clubroot, which persists for years in infested ground. Most Brassica spp. crops tolerate light frost, and the flavor of kale and Brussels sprouts sweetens after cold. Rotating away from beds used by other brassicas reduces disease buildup.

Pruning

Pruning is limited to removing yellowed lower leaves and harvesting outer foliage, which keeps plants productive and improves air circulation. Pinching the growing tip of some leaf crops encourages side shoots. Flower stalks are cut out of leafy crops to delay bolting where seed is not wanted.