Brassica oleracea (Italica Group) 'Ironman'

RHS Plant Profile
calabrese 'Ironman'

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Annual Biennial
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A hardy biennial grown as an annual. A top performing calabrese, popular for use by commercial growers because of its long cropping period between May-October, producing uniform blue-green edible, domed heads. This variety crops quickly, ready to harvest 75 days from transplanting. It shows good tolerance to hollow stem and resistance to bolting

Position

Full sun

Soil Types

Loam, Sand

Max Height

0.5-1 metres

Max Spread

0.5-1 metres

Size

Time to Maturity
1 year
Max Spread
0.5-1 metres
Max Height
0.5-1 metres

Growing Conditions

Loam Sand
Moisture
Well–drained or Moist but well–drained
pH
Alkaline or Neutral

Position

Full sun
Aspect
West–facing or South–facing
Exposure
Sheltered
Hardiness

Hardiness Ratings

All ratings refer to the UK growing conditions unless otherwise stated. Minimum temperature ranges (in degrees C) are shown in brackets

  • H1A: under glass all year (>15C)
  • H1B: can be grown outside in the summer (10 - 15)
  • H1C: can be grown outside in the summer (5 - 10)
  • H2: tolerant of low temperatures, but not surviving being frozen (1 to 5)
  • H3: hardy in coastal and relatively mild parts of the UK (-5 to 1)
  • H4: hardy through most of the UK (-10 to -5)
  • H5: hardy in most places throughout the UK even in severe winters (-15 to -10)
  • H6: hardy in all of UK and northern Europe (-20 to -15)
  • H7: hardy in the severest European continental climates (< -20)
H2

Colour & Scent

Season Stem Flower Foliage Fruit
Spring
Summer
Autumn
Winter

Botanical Details

Family
Brassicaceae
Native to GB/Ireland
No
Foliage
Deciduous
Habit
Clump forming
Genus
Brassicas can be annual, biennial or perennial plants, most are upright with alternate, often glaucous leaves, long taproots and clusters of cross-shaped, yellow or white flowers. The genus includes a number of species bred to produce food crops, such as cabbages, turnips, mustards and oilseed rape, as well as others grown for their ornamental value
Name Status
Accepted

How to Grow

Cultivation

Grow in fertile, well-compacted, non-acid soil in full sun. Sow between March and June at a depth of 1cm and spaced 30cm apart. See calabrese cultivation for more detailed advice

Propagation

Propagate by seed. See sowing vegetable seeds or sowing seeds indoors for further advice

Pruning

No pruning required

Pests

May be susceptible to birds, cabbage caterpillar, cabbage whitefly, cabbage root fly, cutworms, flea beetle, mealy cabbage aphid, slugs and snails, white blister

Diseases

May be susceptible to black rot, club root, downy mildew, grey mould, leaf spot, white blister