Silphium Species, Cup Plant, Cup-Plant

Silphiumperfoliatum var. connatum

Family
Asteraceae (ass-ter-AY-see-ee)
Genus
Silphium (SIL-phee-um)
Synonym
Silphium connatum
Silphium scabrum
Sun Exposure
Full Sun
Foliage
Herbaceous
Height
36-48 in. (90-120 cm)
4-6 ft. (1.2-1.8 m)
6-8 ft. (1.8-2.4 m)
Spacing
18-24 in. (45-60 cm)
Hardiness
USDA Zone 5a: to -28.8 °C (-20 °F)
USDA Zone 5b: to -26.1 °C (-15 °F)
USDA Zone 6a: to -23.3 °C (-10 °F)
USDA Zone 6b: to -20.5 °C (-5 °F)
USDA Zone 7a: to -17.7 °C (0 °F)
USDA Zone 7b: to -14.9 °C (5 °F)
USDA Zone 8a: to -12.2 °C (10 °F)
USDA Zone 8b: to -9.4 °C (15 °F)
USDA Zone 9a: to -6.6 °C (20 °F)
USDA Zone 9b: to -3.8 °C (25 °F)
Bloom Color
Bright Yellow
Bloom Time
Late Summer/Early Fall
Other Details
Category
Perennials
Water Requirements
Average Water Needs; Water regularly; do not overwater
Foliage Color
Where to Grow
Bloom Characteristics
Bloom Size
Other details
Soil pH requirements
6.6 to 7.5 (neutral)
7.6 to 7.8 (mildly alkaline)
Patent Information
Propagation Methods
From seed; direct sow outdoors in fall
From seed; stratify if sowing indoors
Seed Collecting
Allow seedheads to dry on plants; remove and collect seeds
Properly cleaned, seed can be successfully stored
Regional

This plant is said to grow outdoors in the following regions:

Albion, Michigan

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Gardener's Notes:

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positive
1
neutral
0
negative
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sj7
Marlborough, MA | June 2019 | neutral

I grew cup plant when I lived in southern Michigan (zone 5a). It got very tall, up to 6 ft. or more, in not terribly fertile soil. I did ...Read More

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