Mammoth Red Rock cabbage transforms the garden with its stunning reddish-purple heads that weigh 2-4 pounds and develop their rich color without a trace of bitterness. This hardy annual thrives across zones 2-10, making it one of the most adaptable red cabbages you can grow. In just 90 days (though some sources report up to 99 days), compact 12-18 inch plants produce impressive 7-8 inch diameter heads that bring both beauty and flavor to your harvest.
Photo © True Leaf Market
Growing Conditions
USDA Zone
2-10
Sunlight
Full Sun
Water
Moderate
Soil
Well-drained, Fertile Loam With Consistent Moisture
Preferred Temp60-75°F
Growth Stats
18 in
Height
—
Width
18 in
Spacing
90–90
Days to Harvest
PeriodPerennial
TypeForb/herb
Plant Profile
Sunlight
Full Sun
Water
Moderate
Zones
2-10
Size
18in H x ?in W
Growth
Perennial
Care
Moderate
Hover over chart points for details
Highlights
The deep purple-red coloring of Mammoth Red Rock sets it apart from ordinary cabbages, creating dramatic contrast in garden rows and stunning presentations on the dinner table. Despite its bold appearance, this variety offers a surprisingly sweet, delicate flavor that elevates everything from coleslaw to pot roast. The substantial 2-4 pound heads develop quickly for a large cabbage, and the compact plant habit makes efficient use of garden space with its neat mounding growth.
Common Uses
Mammoth Red Rock excels in fresh applications where its vibrant color and sweet flavor shine brightest. The tender leaves create visually striking coleslaws and summer salads, while the substantial heads hold up beautifully in slow-cooked dishes like pot roast where the purple hue adds unexpected elegance. This variety works particularly well in dishes where you want the nutritional benefits and mild flavor of cabbage without any bitter notes.
Growing Timeline
First Bloom
Early-summer
First Harvest
Mid-summer
Last Harvest
Early-fall
Care Instructions
Start Indoors
Sow seeds indoors 5-7 weeks before the last average frost date. After 4 weeks of indoor growth, seedlings will be ready for transplanting outdoors.
Transplant Outdoors
Transplant seedlings outdoors after hardening them off for one week. Plant them 1/2 inch deep with 18 inches between plants in rows spaced 3 feet apart. Wait until soil temperatures are moderate and frost danger has passed.
Harvesting
Harvest when heads feel firm and solid, measuring 7-8 inches in diameter after approximately 90 days. The heads should have developed their full reddish-purple color and feel dense when gently squeezed. Cut the entire plant at harvest rather than leaving stems or roots in the soil, as decomposing plant material can harbor diseases that affect future crops.
Growing Calendar
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Companion Planting
Ecology & Traits
Edible
Scientific Classification
Brassica oleracea L.
Family
Brassicaceae
Genus
Brassica
Duration
Perennial
Growth Habit
Spreading
Native Status
L48 (I)PR (I)CAN (W)GL (W)