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© luc Montroy, some rights reserved (CC-BY-SA) · GBIF
Chrysanthemum
Mammoth Mums Collection
Cultivars derived from East Asian species (China, Korea, Japan)
Overview
Chrysanthemum spp. Mammoth Mums Collection is a curated mix of multiple cultivars from the Mammoth series of cold-hardy garden mums developed at the University of Minnesota. Individual plants reach 24-36 inches (60-90 cm) tall and 36-48 inches (90-120 cm) wide at maturity, forming dense rounded mounds. Stems numerous, branched, and semi-woody at the base. Foliage deeply lobed and aromatic when crushed, leaves 1.5-3 inches (4-8 cm) long, dark green with grey undersides. Flowers daisy-form, single to semi-double depending on cultivar, 1.5-2.5 inches (4-6 cm) across, in the standard Mammoth color range — red, pink, lavender, yellow, white, and bronze; hundreds of flowers cover each plant during peak bloom. Bloom occurs from late August through October in zones 4-7, with peak coverage in mid-September. Plants establish a 24-inch (60 cm) mound within the first season and reach mature spread by year 2. Plants persist 5-8 years in zones 3-7 with adequate winter drainage. Crown rot can develop in heavy clay soils with poor winter drainage. Cultivar composition of the collection varies by supplier and season; mixes typically contain 3-6 different selections.
Native Range
Garden mums in the genus Chrysanthemum are derived from species native to East Asia, principally C. indicum and C. zawadskii (China, Korea, Japan) cultivated for more than a millennium. The Mammoth series was developed at the University of Minnesota Landscape Arboretum in the late 20th century to extend mum hardiness into USDA zones 3-4 where florist-type chrysanthemums fail.Suggested Uses
Used in mass plantings as fall color, in mixed perennial borders at 36-48 inch (90-120 cm) spacing, and in pollinator gardens. The cultivar diversity in the collection produces variation in flower color across a single planting. Containers of at least 7 gallons (26 L) accommodate single plants for 2-3 seasons; container plants need additional winter protection in zones 3-5.How to Identify
Appearance
Size & Dimensions
Height2' - 3'
Width/Spread3' - 4'
Reaches mature size in approximately 2 years
Bloom Information
Late August through October in zones 4-7, with peak coverage in mid-September. Bloom may begin in early August in zones 8-9 and extend into November. Individual flowers last 1-2 weeks; total bloom period extends 8-10 weeks across the plant. Cool nights below 50°F (10°C) extend individual flower lifespan to 2-3 weeks.Detailed Descriptions
Flower Description
variable across collection: red, pink, lavender, yellow, white, bronzeFoliage Description
dark green with grey undersidesGrowing Conditions
Sun Requirements
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
Care & Maintenance
Care Guide
Water weekly during the first growing season in the absence of rain. Established plants tolerate average garden conditions with periodic dry spells, but flower bud formation is sensitive to drought stress in late summer. Mums are short-day plants and form flower buds when night length exceeds 12 hours; nearby outdoor lighting may delay bloom or prevent flowering entirely. Powdery mildew and aphids occur occasionally but do not significantly affect bloom. Crown rot can develop in heavy clay soils with poor winter drainage; raised beds or sandy amendments improve survival in zones 3-5. Mulching crowns with 2-3 inches (5-8 cm) of bark or straw after first hard frost improves winter survival in zones 3-4.Pruning
Pinching growing tips by 2-3 inches (5-8 cm) every 2 weeks from May through early July promotes branching and reduces plant height; final pinch by July 4 in zones 4-7 allows time for bud set. Cut all stems to 4-6 inches (10-15 cm) above ground in late autumn after bloom or in early spring before new growth emerges. Foliage left through winter improves cold hardiness and is removed in early spring.Pruning Schedule
J
F
M
A
M
J
J
A
S
O
N
D
late springsummerfallearly spring
Maintenance Level
moderateContainer Growing
✓ Suitable for container growing
Minimum container size: 7 gallons